Justyn Jackson's Weather Blog

Dual-Pol Applications

2011-10-05T20:06:00.008-05:00

Dual-pol installations are now being pushed in full force across the country. As of this post, eight radars are equipped with dual-pol, including the prototype in Norman, OK; Vance, OK; Pittsburgh, PA; Wichita, KS; Phoenix, AZ; Morehead City, NC; Portland, OR; and Langley Hill, WA. Within the coming months and years, many dual-pol installations are scheduled, and it is expected that all radars will be upgraded by May 2013. To see when the radar nearest to you will have dual-pol capabilities, check out the deployment schedule. To learn basic information about dual-pol, check out NWS Amarillo's page. For more thorough dual-pol training for non-NWS users and/or non-meteorologists, visit the Warning Decision Training Branch page. Without the training or prior knowledge of dual-pol, it will be difficult to understand this post.

Over the course of several blog posts, I'll highlight applications that will show how dual-pol base data can supplement and even enhance polarimetric radar base data. I'm not a fan of derived radar products, so you won't see any dual-pol applications on the hydrometeor classification (HC) product or the melting layer (ML) product. If you want to see those, check out the WDTB's training link above. This post will look at how dual-pol products can be applied to a tornadic supercell.

KOUN 0.5 deg base reflectivity 2114 UTC 24 May 2011.

Cross section of supercell above.

The supercell we'll focus on is in Canadian County, OK, about 35 miles northwest of Oklahoma City. This supercell was part of a prolific tornado outbreak across Central Oklahoma on 24 May 2011 and produced an EF-5 tornado. Analyzing a cross section of this supercell, there's virtually no doubt this was a severe thunderstorm given the presence of a bounded weak echo region, weak echo overhang, significant reflectivities aloft, and a tight, strong and persistent mesocyclone. Given these characteristics and a very favorable ambient environment for tornadoes, the likelihood of this supercell producing a tornado is quite high. The question is, how can dual-pol data add value to what we already know?

KOUN 0.5 deg base reflectivity 2114 UTC 24 May 2011. Z (top left), ZDR (top right), CC (bottom left), and KDP (bottom right).

Let's first examine the core of this supercell and look at base reflectivity (Z) along with differential reflectivity (ZDR), correlation coefficient (CC), and specific differential phase (KDP). Z (top left) shows fairly high reflectivities (>56 dBZ) within the core at ~3,100 feet above radar level. This indicates the possibility of heavy rain and also hail. Several ZDR (top right) values within the white circle are between -1 and 1 dB, indicating the presence of large hail (blue and grey pixels) and melting hail. CC (bottom left) values between 0.82 and 0.95 also indicate the presence of large (possibly up to 1.75 in) and small hail within the core. Where CC values are near or below 0.80 (blue and lime green pixels) and ZDR values are -1 to 0 dB (grey pixels), there is a high likelihood of giant hail (2.00 in or larger). KDP (bottom left) values greater than 1 deg/km (light pink pixels) indicate this supercell has very large rain drops (orange pixels) and is capable of producing very high rain rates.

KOUN 0.5 deg base reflectivity 2114 UTC 24 May 2011. Z (top left), CC (top right), SRM (bottom left), and SW (bottom right).

We can also use dual-pol data to identify non-meteorological scatterers, including tornado debris. Dual-pol data will NOT increase tornado lead time, but it can give a warning forecaster high confidence that a damaging tornado is occurring. As a caveat, in order to detect tornado debris, the lofted debris must be within 70 miles from the radar and must fall within the beam during a volume scan. ZDR can be used to identify debris, but correlation coefficient is the best dual-pol product to use for this. CC values between 0-0.8 are pretty good indicators of tornado debris, if collocated with other tornado signatures. In the image above Z (top left) shows a high, blocky looking reflectivity signature southeast of Calumet within the hook echo. Within this high reflectivity signature, there is a rapidly rotating cyclonic couplet (SRM in bottom left) along with high spectrum width (bottom right) values. Correlation coefficient values within this same area range from 0.2 to 0.78. Therefore, the collocation of all these signatures gives extremely high confidence that a damaging tornado is occurring.

Estimating Downdraft Strength

2011-07-29T22:26:00.004-05:00

If applied correctly, downdraft CAPE (DCAPE) can be a useful tool to forecast potential downdraft strength. DCAPE is best utilized in weakly sheared environments where pulse and multicellular convection will dominate. To compute DCAPE, we'll first look at this qualitatively using a Skew-T (Figure 1). First, we need to find a representative mid-level wet bulb potential temperature, which will indicate where the downdraft may possibly originate. In this example, we assume the downdraft initiates around 575 hPa. However, be cognizant of the fact that most downdrafts initiate over a layer rather than a specific level. The updraft also has a wet bulb potential temperature and is found by lifting the surface parcel to its LCL. The downdraft parcel will be somewhere between the the mid-level wet bulb potential temperature and the updraft wet bulb potential temperature. Since the downdraft parcel follows a saturation adiabat, we assume the downdraft is completely saturated. The downdraft parcel is slightly warmer than the environmental temperature between 580-370 hPa. From the surface to 580 hPa, the downdraft parcel is colder than the environmental temperature, which results in a negatively buoyant layer. The level where the downdraft parcel becomes colder than the environmental temperature is called the level of free sink (LFS) and is similar to the LFC for updrafts. Therefore, DCAPE is an integration of the layer between the environmental temperature and the downdraft temperature from the surface to the LFS.

Figure 1. Skew-T illustrating DCAPE.

In order to determine the potential gust speed of a downdraft, we must calculate DCAPE quantitatively:

DCAPE = 1/2 * g *((Te - Tpd)/Te) * delta z

The terms of the DCAPE equation are:

g - gravity
Te - environmental surface temperature (K)
Tpd - expected downdraft surface temperature (K)
delta z - depth of negatively buoyant air (m)

For this particular case, the environmental surface temperature was 311 K, the expected downdraft surface temperature was 291 K, and the depth of the negatively buoyant air was 3,500 m.

DCAPE = 1/2 * 9.81 *((311-291)/311) * 3500 m
DCAPE = 1,104 m^2/s^2 or 1,104 J/kg

In order to calculate the maximum theoretical updraft velocity (Wmax), we use the equation Wmax =
square root (2*CAPE). We can actually substitute DCAPE for CAPE to calculate the maximum theoretical
downdraft velocity. Therefore, Wmax = square root (2*DCAPE)

Wmax = square root (2*1,104)
DCAPE = 47 m/s or 105 mph

The maximum theoretical downdraft velocity can often be overestimated by almost 50%. The calculated value overestimates the potential downdraft velocity since DCAPE assumes that the downdraft is fully saturated as it descends. In actuality, the downdraft likely warms somewhere between the dry adiabatic and saturated adiabatic lapse rates since the dry subcloud air enhances evaporation, which decreases both DCAPE and the downdraft velocity. However, significant precipitation loading (> 60 dBZ reflectivity core) is not accounted for in DCAPE but can lead to stronger downdrafts than DCAPE suggests. In this particular case, the thunderstorm was too close to the radar to adequately sample whether or not precipitation loading would have contributed to the downdraft (not shown). However, judging by the sounding and the moderately unstable air mass, it's possible that precipitation loading could have played a role.

What happened on this day? A microburst produced a gust of 81 mph at Amarillo just a few hours before this sounding was released.

July 22 Amarillo Microburst

2011-07-24T08:53:00.005-05:00

A microburst occurred during the middle afternoon on July 22 and produced an 81 mph wind gust at Rick Husband International Airport, which tied the highest gust ever recorded at Amarillo. Instead of writing a blog post, I've decided to link to a web story our office created.

Microburst Produces 81 mph Wind Gust at Amarillo -- WFO Amarillo

Massive Heat Bubble

2011-07-18T16:44:00.007-05:00

On the evening of July 17, an expansive 500 mb subtropical upper-level anticyclone was centered near the Kansas and Nebraska border and nearly stretched from border to border in the center part of the United States (Figure 1). The strength and placement of this feature is unusual, and in fact, standard deviations of +2.5 were common near the centroid of the anticyclone (Figure 2). When strong anticyclones like this develop, they are accompanied by unseasonably warm temperatures during the day and at night along with high moisture content. The combination of these factors creates a potentially dangerous situation because the heat can add serious stress on the human body. Accordingly, several heat-related watches, warnings, and advisories were in effect for 16 states (Figure 3) last evening. What compounds matters is that a lot of the heat is expected to be concentrated in urban areas, including Chicago, Milwaukee, and Minneapolis where many people do not have air conditioning or cannot afford to run the air conditioner.

Figure 1. 18 July 2011 00Z 500 mb height analysis

Figure 2. 18 July 2011 00Z 500 mb height standardized anomalies.

Figure 3. Watch, warnings, and advisories for July 17.

It surprises many people to learn that heat kills more people on average that tornadoes and lightning combined. Granted, these statistics are slightly skewed by the 1995 heat wave in the Midwest that killed hundreds of people, but it proves that heat is a very underrated killer.

Kunkel, K. E., S. A. Changnon, B. C. Reinke, and R. W. Arritt, 1996: The July 1995 heat wave in the Midwest: A climatic perspective and critical weather factors. Bull. Amer. Meteor. Soc., 77, 1507–1518.

Amarillo Wake Low

2011-06-29T16:25:00.016-05:00

An unusually strong period of damaging winds occurred during the early morning hours of June 28, 2011 across the southern Texas Panhandle. What was even more unusual was the fact that these winds occurred in the stratiform precipitation region behind a convective complex that stretched from near Pampa to southwest of Clarendon. Damaging wind gusts as high as 69 mph were measured at the Amarillo ASOS, and these strong winds even produced damage across parts of the city. Quite possibly the most remarkable stat from this event is that sustained severe wind gusts occurred continuously for almost an hour. It is believed that these damaging winds were associated with a wake low event.

0600Z Surface Observations

0700Z Surface Observations

0800Z Surface Observations

Observations at 0600Z indicate a rain cooled air mass associated with convection moving across the southwestern Texas Panhandle. The temperature and dew point at Amarillo were 78 and 56, respectively along with a MSLP of 1014.7 mb. By 0700Z, strong convection was moving across Amarillo with the evaportive cooling taking place as evidence by the temperature dropping to 64 and the dew point rising to 64. It was during this time that a mesohigh had developed immediately behind the strongest convection. In fact, the MSLP had increased 4.1 mb in a hour to 1018.8 mb. By 0800Z, inexplicably, the temperature jumped to 71 and the dew point dropped to 56. At the same time, the pressure dropped a whopping 5.5 mb to 1013.3 mb and winds increased significantly in a small corridor just east of Amarillo.

Pressure & Wind Time Series

Temperature & Dew Point Time Series

The changes in temperature, pressure, and wind are best seen through these time series charts. The rapid fall drop in pressure between 0700Z and 0800Z corresponds to a sudden increase in sustained winds and gusts. The wind gust peak at 69 mph around 0753Z and again at 0841Z. At the same time, the temperature rose 7 degrees and the dew point dropped 7 degrees.

This data is consistent with other case studies (Handel and Santos, 2005) and numerical modeling of wake lows (Johnson, 2001). As described by Johnson and Hamilton (1988), wake lows form within the stratiform precipitation region behind the strongest convection. Within this area, evaporational cooling is not able to balance the adiabatic warming that occurs due to the descending rear inflow jet. This can be explained further by comparing the rainfall rate in the region of strongest convection to the stratiform region. Rainfall rates will likely be much higher in the strongest convection, thus increasing the potential for strong evaporative cooling. Meanwhile, the rainfall rate in the stratiform region is much less, which results in less potential for evaporative cooling. In addition, the ambient air within the stratiform region has usually already been evaporatively cooled to a significant degree by the preceding convection. Therefore, the effects of evaporational cooling within the stratiform region are much smaller than compared to the strongest convective region. Within the stratiform region, evaporational cooling is unable to offset the effects of adiabatic warming incurred by any descending air, which can produce locally enhanced dynamic pressure gradients, increased wind speeds, and warmer temperatures.

0600Z LAPS Sounding from Amarillo

0700Z LAPS Sounding from Amarillo

0800Z LAPS Sounding from Amarillo

LAPS soundings show the lower tropospheric warming associated with the wake low between 0600Z and 0800Z. Between 0600Z and 0700Z, this warming is most pronounced between 825 mb and 720 mb with temperatures around 800 mb almost 2 degrees C warmer by 0700Z. Additional low-level warming takes place at 0800Z, and temperatures around 800 mb are almost 3.5 degrees C warmer than at 0600Z.

0801Z IR Satellite Image & Surface Observations

It is interesting to observe infrared satellite imagery where a localized area of warmer cloud tops was most pronounced from southern Randall County to western Carson County. This warm pocket also coincided with an area of higher temperatures, lower dew points, and stronger winds.

0739Z 0.5 deg KAMA Base Reflectivity

Base Reflectivity Cross Section

Base Velocity Cross Section

0747Z 0.5 deg KAMA Base Velocity

Even within the stratiform region, very little precipitation was occurring at the surface or aloft in the area of strongest winds. However, base velocities were extremely impressive, especially in the lowest 2,000 feet ARL. In the bottom image above, 60-68 kt inbound velocities were even sampled around 120 feet ARL. These base velocity winds were likely quite accurate as target motion was moving parallel to a radial.

How can wake lows be forecast? Well, it's virtually impossible to predict the formation of these phenomena in advance, but an understanding of how they form and the circumstances they form in can help forecasters to quickly recognize the potential for wake low development. Attentive monitoring of observational and radar data is the most critical element to the detection and diagnosis of wake lows.

Forecasting Severe Hail

2011-06-13T16:15:00.008-05:00

This blog post will attempt to describe thermodynamic and dynamic characteristics I look for when forecasting severe hail. Some factors, such as storm microphysics and kinematics, are currently impossible to analyze/forecast but play an equally large role in governing the threat for severe hail.

Buoyancy: The environment was moderately unstable with a 2,435 J/kg of SBCAPE and very little SBCIN (-2 J/kg). Although the CAPE profile is fairly deep, it is rather thin. Within the hail growth zone, there appears to be about 820 J/kg of CAPE.

Deep layer shear: Despite relatively weak winds in the lowest 4 km, the degree of veering and the stronger winds near 6 km more than make up for this. 0-6 km shear of 37 kt is more than adequate. Even stronger winds are noted at 7 and 9 km.

Mid-level lapse rates: A 700-500 mb lapse rate of 6.2 C/km is respectable for a tropical environment. However, the lapse rate within the hail growth zone is closer to moist adiabatic.

Freezing level: 14,381 feet is rather high and likely allowed for more melting. The deep moist layer from the surface through ~650 mb also increased the melting potential of hail stones.

Overall threat: The threat for severe hail is pretty high based on this sounding. The buoyancy alone should allow for at least some threat for severe hail. However, the decent deep layer shear and large CAPE in the hail growth zone certainly increase the hail threat. Some negative factors for significant hail (2" or larger in diameter) are the weaker lapse rates in the hail growth zone, the high freezing level, and the moist profile from the surface to about 650 mb.

Summary: A few reports of hail up the golf ball size were reported in Broward County. This is extremely rare for the middle of June, but the thermodynamic and dynamic environment was supportive. Additionally, storm microphysics and kinematics were likely very favorable for severe hail production.

It should also be mentioned that this sounding profile was also quite favorable for wet microburst production. Indeed, several severe wind gusts were reported, including a 64 mph gust measured at Weston, FL.

Severe Thunderstorm Rocks Western Broward Metro -- WFO Miami

May 24 Chase -- Canton Tornado

2011-05-28T21:17:00.013-05:00

Another devastating tornado outbreak struck the southern Plains on May 24. Hardest hit was Central Oklahoma where three EF-4 tornadoes have been confirmed. By early afternoon, storms initiated rapidly along a sharpening dryline across western and Southwest Oklahoma and quickly evolved into supercells. The first supercell of the day formed near Elk City and moved toward the northeast. As the supercell passed west of Oakwood, it began to tighten up with two distinct wall clouds present for almost 10 minutes. Shortly thereafter, one dominant circulation took over, and it was obvious this storm was getting ready to produce a tornado. Indeed, a few miles west of Canton, a tornado developed, tracked northeast for nine miles, and lasted for nearly 30 minutes. Initially, the tornado was small but quickly grew to a one-half mile-wide multiple vortex stovepipe northwest of Canton. The tornado was rated an EF-3, and unfortunately, it injured two people near Canton Lake. Below are some images (courtesy of TB), video, and links documenting the storm chase. If you feel compelled to help tornado victims of this outbreak, you can donate to the American Red Cross.

A very sharp dryline across western Oklahoma served as a focusing mechanism and helped initiate supercell thunderstorm.

Classic supercell with dual wall clouds north of Thomas, OK.

Low, ragged wall cloud northwest of Oakwood, OK.

Ragged wall cloud with a well-defined beaver's tail.

Rotating wall cloud just west of Canton, OK. RFD can be seen to the left and behind the wall cloud. Rotation rapidly increased as the RFD interacted with the updraft base.

Tornado develops after RFD ingestion.

Tornado becomes larger as it moves northwest of Canton.

Large, multiple vortex tornado northwest of Canton.

VIDEOS

Radar Images of Joplin Tornado Updated

2011-05-23T08:25:00.012-05:00

Since the April 27 tornado outbreak, the weather pattern has been largely unfavorable for widespread severe weather due to a maritime tropical air mass regime remaining confined to the Gulf Coast states. However, the pattern began to change over the last several days as a western CONUS trough developed and propagated eastward. This allowed for a sustained period of moisture return across the center portion of the country. As the trough axis and embedded disturbances within the trough have ejected towards the Plains, they have encountered a much more buoyant and highly sheared environment.

The end result the last couple of days has been a return of widespread severe weather, including tornadoes, from the southern Plains to the northern Plains. The hardest hit area was Joplin, MO where an EF-5 tornado cut a damage swath up to three quarters of a mile wide across the southern part of the city yesterday evening. Most troubling is the fact that 125 deaths have been confirmed as a result of this tornado, which makes this the eighth deadliest tornado in recorded U.S. history.

My thoughts and prayers go out to all those affected by the severe weather. If you feel compelled to help victims of the tornado, you can donate to the American Red Cross. Below are some radar images of the powerful tornadic supercell as it moved across Joplin.

0.5 deg base reflectivity scans at 2243Z (top) and 2248Z (bottom) show a classic hook echo along with the infamous debris ball signature.

A cross section of the supercell reveals more about it's 2-D structure. A very strong updraft can be inferred by a weak echo region and a bounded weak echo region located between ~9,000 and ~15,000 feet above radar level.

0.5 deg storm relative motion (using a storm motion vector of 270 deg, 24 kt) at 2243Z (top) and 2248Z (bottom) shows an intense low-level mesocyclone. The 2243Z scan had a maximum rotational gate-to-gate couplet of 188.3 kt at ~4,900 ft above radar level. The 2248Z scan had a maximum rotational gate-to-gate couplet of 185.5 kt at ~4,700 ft above radar level.

The 2248Z volume scan shows extremely intense storm top divergence near 50,000 ft. A maximum outbound velocity of 193.8 kt and a maximum inbound velocity of 111.5 kt shows the strength of this supercell.

Initiation to Dissipation -- Smithville, MS Tornadic Supercell

2011-05-17T17:19:00.019-05:00

I'll be starting a new series on this blog called Initiation to Dissipation. I'll be using radar images from the historic April 27 tornado outbreak to show the life cycle of some of the worst tornadic supercells and some of the most impressive signatures during their life cycles. The first supercell featured will be the one that produced an EF-5 tornado in Smithville, MS.

Convective initiation of this supercell began around 1643Z in Northeast Louisiana near Rayville.

Over the course of the next hour, this storm strengthened and began to develop a weak mesocyclone. Within the storm's first hour, it initially had a difficult time time separating itself from other convection. It's possible that hodographs were not as strongly curved in the lowest three kilometers, thereby making deep layer shear vectors more parallel to the pre-frontal trough that the storms initiated along.

By 1843Z, however, hodographs appeared to become increasingly favorable for semi-discrete supercells. In fact, the storm had clearly became separated from other convection and even had unimpeded inflow into the updraft region. Weak supercell characteristics were seen by this time with as a weak echo region (WER) was present along with a weak, persistent mesocyclone.

An hour later, the supercell appeared to be entering its mature stage. Distinct supercell characteristics were noted, including the presence of a WER, a bounded weak echo region (BWER), a strong mesocyclone, and a hook echo.

By 2042Z, the supercell is located near Smithville and likely near its peak intensity. A very tight concave reflectivity gradient is present in the inflow region of the supercell, a very impressive WER and BWER were also present, a hook echo persisted, and a very strong low and mid-level mesocyclone were still present.

A zoomed in image of the supercell west of Smithville (left) shows an impressive BWER at around 9,300 feet. As the supercell moved northeast of Smithville, a tornado signature can be seen in the storm relative motion data along with a very high normalized rotation (NROT) value typically only seen in intense mesocyclones and tornadoes.

By 2142Z, another cell had merged with the supercell and seemed to interfere with its structure. Nonetheless, a strong mesocyclone remained present along with a WER.

The supercell remains in tact another hour later, but it's clearly not as well-defined as it once was over Northeast Mississippi. It also becomes apparent that convection to its south may likely further disrupt the updraft.

Indeed, by 2343Z, the storm has weakened considerably and shows no signs of supercell characteristics.

By 00Z, the storm had pretty much dissipated but not before traveling a total of about 437 miles!

Damage Survey Images

Scenes and Thoughts From Tuscaloosa

2011-05-14T21:53:00.008-05:00

One of the worst tornado outbreaks in United States history occurred on Wednesday, April 27, 2011. 134 tornadoes have been confirmed (as of May 9) across 17 states with Alabama being the hardest hit. During a 24-hour period from 8 a.m. on April 27 to 8 a.m. on April 28, 309 people were killed, including 236 in Alabama.

Why did so many people die? I believe this article does an excellent job of providing many answers. Many folks in the meteorology community may disagree with me, but I don't think there's a lot to be learned from this event from a scientific meteorological perspective. It was extremely well forecast by the Storm Prediction Center and local Weather Forecast Offices up to five days in advance. However, I think there is a tremendous amount that we can and will learn about societal impacts from this tornado outbreak.

Arguably, the most recognizable tornado from this outbreak was the Tuscaloosa-Birmingham tornado. This tornado was rated an EF-4, it produced a continuous damage path for 80.3 miles, and it killed 65 people. It is the single deadliest tornado since May 25, 1955. Tuscaloosa was particularly hard hit where 41 fatalities occurred. A few days after the tornado, I traveled to Tuscaloosa to help out my mom and sister who were hit by the tornado and to get a firsthand view of the destruction. I witnessed the damage from the F4 tornado in Tuscaloosa on December 16, 2000, and I can attest that the magnitude and spatial extent of this damage was much worse.

The aerial image above shows the damage and devastation in the Forest Lake neighborhood associated with the April 27 tornado in Tuscaloosa. The numbers on the aerial image indicate where ground-level images were taken on April 30.

Image 1 was taken at 19th Street East and included a miracle story of survival. The house in the foreground was a single-level home with a basement. The house was completely destroyed with much of the rubble collapsing in the basement. The homeowner was an elderly woman that sought shelter in the basement, only to have her house collapse on top of her. After the tornado passed, a few students living across the street pulled the woman out of the wreckage. She sustained only minor injuries.

Image 2 is looking across Forest Lake at heavily damaged and destroyed homes along Forest Lake Drive where EF-4 damage occurred. Trees were also snapped, debarked, and thrown into the lake. Other debris in the lake included a refrigerator and a basketball goal.

Image 3 was taken near 1st Avenue and Fernwood Court. Part of a metal roof from University Place School was found twisted around a tree.

It's events like this that are the driving motivator of my career. Fortunately, I've never worked an event where lives have been lost, but I realize that won't be the case forever. However, after hearing the horror that my family went through and seeing many of my great childhood memories reduced to rubble, I have an even greater appreciation for my job as a warning forecaster.

Despite the circumstances in Tuscaloosa, I have complete confidence that the city will rebuild better than ever. I will be forever amazed at the amount of support and unity that I witnessed -- it was truly inspiring. If you feel compelled to help tornado victims, you can donate to the American Red Cross.

Vilonia, Arkansas Tornado

2011-04-25T21:10:00.007-05:00

The atmosphere continues to unleash wave after wave of severe weather outbreaks. Since April 9, there have been eight days in which significant tornadoes have occurred. This evening added to that total as a long track tornadic supercell plowed across towns northwest of Little Rock. The hardest hit location appears to be the town of Vilonia. According to early police reports, the town of Vilonia is "gone". The radar image below is the 0.5 degree cut, which sampled this tornadic supercell at 800 feet above ground level.

This is one of the most impressive tornado signatures I've seen on base radar data. The SRM (using a storm motion vector of 232 degrees and 39 kt) indicated a maximum inbound velocity of 81.6 kt with a maximum outbound velocity 87.4 kt. The base reflectivity showed a debris ball signature along with very high spectrum width values collocated within the debris ball. These signatures give radar operators a high degree of confidence that a tornado is occurring.

St. Louis Struck by Tornado

2011-04-22T21:05:00.003-05:00

A very active severe weather month continued today across the southern Plains and mid-Mississippi Valley. As of this posting, there have been 194 severe weather reports, including 13 reports of tornadoes. The most significant tornado appears to have occurred in the St. Louis metro area this evening. Below is a four-panel radar image (0.5 deg) of a tornadic supercell moving across the northwest side of St. Louis around 8:03 p.m.

The top left panel is base reflectivity, the top right panel is base velocity, the bottom left panel is storm relative motion, and the bottom right panel is spectrum width. X marks the spot of Lambert-St. Louis International Airport. Three minutes after this radar image, the FAA weather observer reported a tornado visible from the airport. Here is the full METAR:
KSTL 230111Z 29022G34KT 240V310 3SM +FC -TSRA FEW020 BKN050CB OVC090 22/19 TORNADO B10 W MOV E AO2 PK WND 29034/0111 CONS LTGICCGCC ALQDS TS ALQDS MOV E P0001

May 10-11 Chases

2010-05-12T21:52:00.016-05:00

I had a couple of off days on Monday and Tuesday, so I took the opportunity to take a mini chase vacation with my buddies Michael Carter, Greg Nordstrom, and Tim Wallace. Fortunately, the weather pattern was very cooperative from a chasing standpoint, and we all felt confident about a powerful western U.S. trough impacting the southern Plains more than a week and a half before the event. Unfortunately, damage, injuries, and fatalities occurred as a result of the May 10 tornadoes across Central Oklahoma. As part of a quick recap, I've compiled some video, links, and damage surveys from the wedge tornado we came within at least 200 yards of near Cromwell, OK.

VIDEOS

Video by Greg Nordstrom

Video by Michael Carter

May 10, 2010 Tornado Outbreak -- WFO Norman

May 10, 2010 Severe Storms and Tornadoes -- WFO Tulsa

CIMSS Satellite Perspective

Michael Carter's Chase Summary

STORM SURVEYS

-From WFO Norman-
...TECUMSEH TO CROMWELL AND POINTS EAST TORNADO...

RATING: EF-3
MAX WIDTH: 3/4 TO 1 MILE
PATH LENGTH: AT LEAST 30 MILES ONLY COUNTING NWS NORMAN PORTION
BEGIN POINT: ABOUT 2.8 WSW TECUMSEH
END POINT: CONTINUED INTO NWS TULSA AREA ABOUT 0.8 E CROMWELL

THIS LONG TRACK TORNADO MOVED FROM POTTAWATOMIE COUNTY INTO SEMINOLE COUNTY...AND THEN CROSSED INTO OKFUSKEE COUNTY WHICH IS IN THE NWS TULSA COUNTY WARNING AREA. THE TORNADO CAUSED SIGNIFICANT DAMAGE ALONG THE ENTIRE TRACK...WITH NO NOTABLE GAPS IN DAMAGE ALONG THE LENGTH OF THE PATH SURVEYED. AT TIMES...THE DAMAGE FIELD WIDENED TO ABOUT 3/4 OF A MILE WIDE...POSSIBLY UP TO 1 MILE WIDE. THE MOST INTENSE DAMAGE SEEMED TO BE JUST NORTH AND NORTHEAST OF EARLSBORO NEAR THE POTTAWATOMIE-SEMINOLE COUNTY BORDER. IT WAS IN THIS LOCATION THAT A 5 BEDROOM...2 STORY FOUNDATION HOUSE WAS DESTROYED EXCEPT FOR SEVERAL INTERIOR WALLS NEAR THE BATHROOM. IN THIS SAME VICINITY...A PICKUP TRUCK APPEARED TO HAVE BEEN LOFTED FOR ABOUT 1/4 MILE...AND A SEMI TRAILER WAS ROLLED OR LOFTED FOR A FEW HUNDRED YARDS. BOTH OF THESE LARGE MISSILES WERE DRAWN FROM THE NORTHERN HALF OF THE DAMAGE PATH TOWARDS THE CENTER. A LITTLE FURTHER EAST...7 HIGH TENSION TOWERS WERE DOWNED. ALONG THE ENTIRE PATH...TREE DAMAGE WAS NOTED...AND A FEW TREES WERE DEBARKED AND STRIPPED OF ALL THEIR BRANCHES.

-From WFO Tulsa-
A TORNADO THAT MOVED ACROSS PORTIONS OF NORTHERN HUGHES COUNTY...INCLUDING THE TOWN OF CROMWELL...CROSSED INTO SOUTHWESTERN OKFUSKEE COUNTY 3 MILES WEST OF BEARDEN AT ABOUT 635 PM CDT. THE TORNADO MOVED NORTHEAST AND DISSIPATED JUST SOUTH OF I-40 ABOUT 3 MILES NORTH OF BEARDEN AT ABOUT 647 PM CDT. MANY TREES WERE DAMAGED IN THE PATH...WHICH WAS ABOUT 5 MILES LONG AND HAD A MAXIMUM WIDTH OF 400 YARDS. BASED ON THE TREE DAMAGE...THE TORNADO WAS RATED EF-1 ON THE ENHANCED FUJITA SCALE WITH MAXIMUM WIND OF UP TO 95 MPH.

MAY 11
This day proved to be a lot quieter than May 10, but one dominant supercell did develop ahead of the triple point across Northwest Oklahoma. After a couple of rounds of deep moist convection failed to sustain itself, likely due to a capping inversion, one LP supercell developed near Crawford, OK just after 6:30 p.m. The supercell slowly moved to the northeast, produced significant hail southwest of Woodward, and eventually dissipated near Freedom, OK. The laminar nature of the storm's base prevented this from being a tornado threat, but hordes of chasers were treated to a beautiful spectacle at sunset.

Video by Greg Nordstrom

Satellite Perspective of April 24 Tornado Outbreak

2010-04-29T11:05:00.003-05:00

CIMSS has put together a very good satellite analysis of the April 24, 2010 tornado outbreak across the Deep South. A few MODIS images are included at the bottom of the recap, which show the tornado scar left in the wake of the Yazoo City tornado.

CIMSS - Deadly tornado outbreak across the Deep South

Yazoo City Tornado Chase Accounts

2010-04-25T18:53:00.003-05:00

I've linked a couple of worthwhile storm chase accounts about the preliminarily rated EF3 tornado in Yazoo City, MS on April 24, 2010. Two of my good buddies, Greg Nordstrom and Michael Carter, provide some insight into the synoptic and mesoscale setup for yesterday's tornado outbreak and discuss issues related to storm chasing in the Deep South.

Greg Nordstrom's Chase Recap

Michael Carter's Chase Recap

Snow Overnight, Near Blizzard Conditions Possible

2010-03-19T07:42:00.006-05:00

Big changes are in store today as a strong trough approaches from the Four Corners region. At the surface, a cold front currently stretches from the Lower Peninsula of Michigan to Central Kansas to Morton, TX along with a weak surface low near Plainview. Due to the anafrontal nature of the front, almost all of the precipitation is well behind the front across Colorado, Nebraska, and Northwest Kansas. There are a few patches of drizzle across the Panhandle, but the main brunt of the precipitation will arrive overnight. In the meantime, skies will become increasingly cloudy as the day progresses. The warmest temperatures of the day occurred at midnight, but temperatures this afternoon will warm slightly to around 44. With a tightening pressure gradient at the surface, winds could gust as high as 35 mph, especially after 5 p.m.

By this evening, the frontal boundary should be well south of the area with an a surface low just north of Midland. This system will deepen and move eastward as strong dynamics eject eastward. As DPVA impinges of the Panhandle, deep layer ascent will support a band of snow that will be moving into the area from the northwest and New Mexico. Once the snow begins after 10 p.m., it should last through Saturday afternoon. The snow will increase in intensity between midnight and 4 a.m. as impressive omega lifts abundant moisture into the snow growth region. Snow ratios will range from 12:1 at the onset of the event to 25:1 at the end of the event. This will support a wide range of totals across the area, but Amarillo will likely end up with around 6" of snow after accounting for above freezing ground temperatures that will initially reduce accumulations. NNE winds will become very strong tonight with gusts possibly up to 50 mph, particularly after midnight. This will cause considerable blowing and drifting of snow and present significant travel problems. Lows tomorrow morning will be near 23, but strong winds will likely result in wind chills near 0 at times.

Mostly Sunny, Mild

2010-03-18T07:51:00.004-05:00

In advance of a potent trough moving through the Pacific Northwest, an upper level ridge will become established across the entire region today. At the surface, weak low pressure in eastern Colorado and high pressure across the Texas Gulf Coast will produce a breezy southerly flow with some gusts up to 25 mph this afternoon. This will result in a beautiful day with mostly sunny skies and mild temperatures. A few high clouds could pass across the area at times today, but these should stay mostly north of Amarillo. Highs this afternoon will top out around 69. Clouds will be thickening and lowering this evening as the trough digs into the Southwest U.S. Ahead of a cold front approaching the Panhandles, the combination of increasing clouds and southerly winds will result in warmer temperatures tomorrow morning with lows around 40.

Mostly Sunny, Pleasant

2010-03-16T07:35:00.004-05:00

The strong shortwave trough and associated rain shield that affected the region yesterday is slowly rotating eastward across the Permian Basin. The Panhandle region will experience deep layer subsidence today in the wake of this system and as high pressure builds in from the north. As a result, clouds should dissipate shortly and allow for an abundant supply of sunshine after 9 a.m. Highs will top out around 58. North northwest winds will be breezy today with some gusts up to 20 mph possible. Another disturbance will approach the area from the north tonight, but there will be no moisture to work with. Therefore, skies will be mostly clear with light winds and dry air, which should allow lows to dip down to 32 tomorrow morning.

Rain This Morning, Mixing With Snow This Afternoon

2010-03-15T07:48:00.003-05:00

Upper air analysis shows a shortwave trough centered over Southwest New Mexico. The main forcing associated with the shortwave will move through the Trans-Pecos region, but some weak disturbances will rotate around the trough. These disturbances have resulted in some areas of moderate to heavy rain and thunderstorms this morning across the region, but mainly light rain has fallen so far in Amarillo. Rain will continue this morning and will likely increase in intensity. Rain and clouds will keep temperatures on the chilly side today with temperatures slowly dropping into the mid 30s by this afternoon. Forecast soundings suggest that wet snow will begin to mix with the rain around noon and then transition to all snow this afternoon as wet bulb zero heights drop under 1,200 feet. It's possible that there could be some minor accumulations (i.e. a dusting or less) of snow on grassy and elevated surfaces, but the recent warm temperatures have allowed soil temperatures to increase. Another forecast consideration today will be the strong northeast winds, which could gust as high as 30 mph. The snow should by 10 p.m., but clouds will hang tough overnight. Lows tomorrow morning will be near 32.

Sunny, Windy, & Warmer

2010-03-12T07:31:00.004-06:00

A closed upper air trough will spin over the Mid South today while high pressure over Central Colorado will produce downsloping northwest flow at the surface. The combination of the two will allow for sunnier, drier, and warmer weather today. Although highs will top out around 58, that will still be about 3 degrees below normal. It will also be windy today with some gusts up to 40 mph possible this afternoon. Decoupling will occur after sunset and winds will begin to subside. With light winds, dry air, and clear skies, strong radiational cooling will occur tonight. In fact, lows will likely be around 29 tomorrow morning.

Showers/Storms This Morning, Windy This Afternoon

2010-03-08T07:46:00.006-06:00

A few showers and thunderstorms are ongoing just west of Amarillo this morning. A strong closed low over New Mexico and the left front quadrant of a cyclonic jet are promoting large-scale ascent over the region. Meanwhile, at the surface, a Pacific cold front is located along the New Mexico/Texas state line. All of these features will move eastward through this morning and afternoon, and it should allow the rain and thunderstorms to end from west to east. Any storms that develop today could be strong with small hail possible due to mid-level instability. The front should pass through Amarillo after 1 p.m. with some breaks in the clouds possible this afternoon. As a result, temperatures should be able to top out near 60. It will be breezy this morning, but winds will really gust once the front sweeps through. Winds could gust as high as 45 mph this afternoon and evening. Low clouds will return before midnight as the upper air disturbance rotates through. A few showers are not out of the question, but these should remain to the north of Amarillo. Skies will gradually clear after midnight, which will allow temperatures to drop near 37 tomorrow morning.

Sunny This Afternoon, Continued Mild

2010-03-05T07:45:00.003-06:00

Some low clouds have developed across the Panhandles this morning as low-level moisture has increased in response to the low-level jet. A potent shortwave trough is passing to the north in Colorado this morning, and once it pulls away this afternoon, slightly drier air will begin to filter back into the area. It does appear that clouds will hang around through 11 a.m., but skies should be mostly sunny this afternoon. Temperatures will warm above average again with downsloping winds compensating for cooler temperatures as compared to yesterday at 700 mb. The end result should be highs topping out near 69. Winds will be strong again today with gusts over 25 mph. There should be enough dry air in place tonight to prevent fog formation. However, clear skies and and relatively light winds will allow temperatures to drop quickly once the sun sets. Lows tomorrow morning will be near 32.

Sunny & Mild

2010-03-04T07:34:00.003-06:00

It's a quiet, cool morning with some patchy areas of fog around the area. This should dissipate after 9 a.m. with mostly sunny skies thereafter. A potent shortwave trough over Nevada looks to stay to our north through the period, but this disturbance will initiate a weak lee side low in Colorado. As a result, the pressure gradient will tighten and wind gusts could be in the upper 20s this afternoon. It will be another pleasant day with highs topping out around 67. Skies will be mostly clear this evening, but a few high clouds may clip the northern part of the Panhandle. Otherwise, some patchy areas of fog could develop again after 2 a.m. Lows tomorrow morning will be near 37.

A Few A.M. Clouds, Warmer

2010-03-03T07:46:00.003-06:00

Some patchy freezing fog and a few high clouds are evident this morning along a building upper ridge over the High Plains. These clouds and fog should move to the east and dissipate later this morning. After they do so, a beautiful day is on tap as high pressure shifts into Missouri and allows for southeasterly surface winds. Highs should be able to top out around 60. Winds will become breezy this afternoon as mixing takes place, and some gusts could approach 25 mph. Skies should be mostly clear tonight, but winds will likely be stronger overnight. This should prevent any fog from developing, but if winds consistently remain under 10 mph, some patchy areas of fog may develop. Lows will dip down to 33.

Sunny, Warmer

2010-03-02T07:48:00.003-06:00

There are some patchy areas of fog and low stratus across the eastern Panhandles this morning, but these should dissipate after 10 a.m. A very nice day is in store as we'll be on the eastern fringe of an amplifying upper ridge over the Rockies. Convergent flow aloft is sustaining two areas of high pressure over Colorado and Kansas. Deep layer subsidence and weak downsloping will allow for abundant sunshine and warmer temperatures. Highs should top out around 55 this afternoon. Winds will be weak this morning, but they will likely become breezy this afternoon with some gusts up to 20 mph. I am worried that some high clouds in the Desert Southwest associated with the southern branch of the jet will graze the area tonight. Still, skies should be mostly clear with light winds and dry air. This will result in decent radiational cooling conditions, which will allow lows to dip down to 32.

Mostly Cloudy, Cool

2010-03-01T07:58:00.004-06:00

A powerful upper air system that moved through over the weekend has exited to our east this morning. In its wake, wrap around clouds, light rain and snow, and cold air advection will keep temperatures on the chilly side today. Some light rain will be possible through 11 a.m., but I think we'll likely remain dry. Forecasting the dissipation of the cloud cover will be the key to today's temperatures. As the upper air system moves into eastern Texas we should see clouds slowly break up around lunchtime, but I am worried that a weak upslope component to the wind could allow clouds to hang tough through the afternoon. I'll be optimistic and forecast some breaks in the clouds after noon, but it will still remain mostly cloudy. Highs should top out around 44 this afternoon, which will be 14 degrees below normal. Winds will be breezy this morning, but should subside throughout the day as high pressure begins to build into the region. Fog will likely be a concern tonight, particularly after 10 p.m. Lows tomorrow morning will dip down to 29. We should get into a warmer pattern by mid week as a trough moves into California and amplifies a ridge across the High Plains. Highs should be back into the 60s by Wednesday. Thursday may be an exception as cool upslope flow develops, but highs should rebound nicely in time for the weekend.

Temperatures Remaining Below Normal

2010-02-26T07:48:00.003-06:00

Skies are mostly cloudy this morning as a result of an approaching upper level disturbance. The strongest forcing associated with the shortwave trough will stay well to our south. Although weak pieces of upper level energy will be moving across our area, the air is very dry in the lowest 5,000 feet. Therefore, I think we should remain dry today. With extensive mid-level cloud cover, highs will continue to be well below normal as we top out around 54. Skies should slowly begin to clear after 9 p.m. With light winds and dry air in place, temperatures will be chilly again tomorrow morning with lows near 31.

Saturday and Sunday look to be transition days before our next storm system arrives on Monday. A slight warm up is expected Sunday, but the suppressed storm track supports below normal temperatures. A few clouds will be possible tomorrow with highs in the low to mid 50s. Saturday will feature mostly sunny skies with highs in the mid 50s. Our next chance of rain will be late Monday night and Tuesday. With the recent upturn in the SOI and the blocking across Canada weakening, I expect a brief warm up after March 5.

Sunny, Cold

2010-02-25T07:13:00.003-06:00

It's very cold this morning with temperatures running in the mid 20s. A messy upper air pattern will begin to evolve today as a strong trough pivots over the Eastern Seaboard and a shortwave trough ejects out of the Four Corners. Weak energy will emanate from the trough in the West and move in our general direction tonight. We should get through the daylight hours with an abundant supply of sunshine, but it will be chilly as a Canadian high pressure dominates. Highs should top out around 49 this afternoon, which will be 15 degrees below normal. A few high clouds will increase before midnight in advance of subtle upper level disturbances approaching the area. However, the strength of this air mass should still allow lows to dip down to 28. If you're tired of the cold weather, hang tight because it looks like a warmer weather pattern will develop in the next 10 days.

Light Rain, Flurries Possible Overnight

2010-02-23T07:54:00.004-06:00

Colder air has filtered into the state as a northern stream trough digs into the Mid South. Meanwhile, a shortwave embedded in the southern stream will approach from the west. The southern stream disturbance will be the one to watch because it is generating a large swath of wintry precipitation across Texas. We won't have to deal with any precipitation issues during the day. Cloud cover will be an issue today, and it appears that low clouds are slowly eroding across Pickens County. The erosion is trying to work its way to the east, and it's possible that we may see some broken clouds this morning. However, clouds will thicken again this afternoon in advance of the southern stream disturbance. Highs should top out around 53 this afternoon if we can get a few peeks of sun this morning.

By this evening, most of the precipitation that is currently over Texas will weaken as it moves eastward. However, as the northern and southern stream disturbances begin to phase, some light precipitation may develop after 3 a.m. Forecast soundings suggest that a mix of rain and some snow flurries will be possible, but no travel problems are anticipated since surface temperatures will remain above freezing. In fact, lows tomorrow morning will be near 37. A chilly and active weather pattern looks to continue for the next week plus.

Cloudy, Slightly Cooler

2010-02-22T07:43:00.005-06:00

Yesterday's high of 72 was the warmest temperature since November 15, but don't get used to the warmth because cold air is poised to return to the state this week. A cold front swept through the state earlier this morning and was accompanied by some light to moderate rainfall. Although we experienced a frontal passage, temperatures will not be extremely cold due to the Pacific origin of the air mass. However, extensive cloud cover in the wake of the frontal passage will ensure that highs top out around 59 this afternoon. Clouds don't look to break up very much, if at all, tonight. The pressure gradient will tighten after 9 p.m. and winds could gust over 20 mph at times through sunrise. Lows tomorrow morning will be near 39. Enjoy today because it could be the last mild day for possibly a week and a half. Starting Wednesday, highs will be much below normal for the foreseeable future.

Mostly Sunny, Comfortable

2010-02-19T07:55:00.003-06:00

Today will seem like a heat wave compared to recent temperatures, but temperatures today will still be slightly below normal for this time of the year. A subtle disturbance moving out of the Gulf of Mexico is creating some cloud cover to out south and west. Some of this cloud cover, mainly high cirrus clouds, will arrive later this morning, but it should not have a major impact on afternoon highs. The main weather influence today will be a surface high shifting to our east, which will allow highs to top out around 60. Skies should be mostly clear tonight with lows dipping down to 31.

On Saturday, a disturbance digging into the Southwest U.S. will pump a ridge over the southern Plains and Southeast. This should result in a full blown heat wave across the region this weekend. Saturday looks excellent with just a few clouds in the afternoon. Highs should be in the mid 60s. Clouds will return Sunday in advance of a developing storm system, but I think we'll be dry through the daylight hours. Highs should top out in the mid 60s. Rain will return late Sunday night. Colder air will return Tuesday with highs below normal again, but this air mass does not appear to be as cold as recent air masses.

Sunny, Slightly Warmer

2010-02-18T07:53:00.002-06:00

As our upper level flow becomes more zonal through the day, temperatures will moderate, but highs will still remain below normal. High pressure situated over the Deep South will promote strong subsidence and an abundant supply of sunshine. Highs should top out around 56 this afternoon. With high pressure almost directly over the area tonight, temperatures will be primed to drop quickly once the sun sets. Lows tomorrow morning will be near 26.

Mostly Sunny, Slightly Warmer

2010-02-17T07:13:00.002-06:00

Upper level disturbances continue to rotate around the deep trough over the Northeast U.S. When the uplift associated with these disturbances encounters some lingering low level moisture, low clouds develop. A few passing clouds will be possible this morning, but we should be mostly sunny this afternoon. As the aforementioned trough moves northeast, low level temperatures will slowly warm. This warming aloft should correspond to slightly warmer temperatures at the surface today, but still well below normal (normal high is 61). Highs should top out around 50 this afternoon. Winds may also be breeze this afternoon with gusts between 15 and 20 mph. Another weak upper level disturbance will approach the area before midnight, so a few passing low clouds may be possible. Otherwise, skies should be clear overnight with dry air and clear skies. As a result, temperatures will be very chilly tomorrow with lows around 26.

Afternoon Clouds, Continued Cold

2010-02-16T07:46:00.004-06:00

Skies cleared even faster than I imagined, and not surprisingly, temperatures are in the lower 20s this morning. An arctic high over the northern Plains will cause northwest surface winds across the area, which will lead to another chilly day. With strong surface heating and cold air aloft, we'll likely see some cumulus clouds develop late this morning and afternoon. Despite this, highs should be able to top out around 45. Winds will remain breezy today with wind chills remaining in the 30s for most of the day. Light winds and clear skies will support strong radiational cooling conditions overnight. Lows tomorrow morning will be around 25.

Mostly Sunny, Cold; Increasing Clouds Tonight

2010-02-15T08:05:00.004-06:00

As is usually the case with Alberta Clippers, this one did not produce a lot of precipitation. Snow accumulated on the tops of cars overnight, but the bigger problem has been the icy patches on area roadways. These ice patches should melt within the next couple of hours as temperatures rise above freezing. In typical clipper fashion, much colder air has invaded the state with freezing temperatures being observed well south of Montgomery. Other than a few passing clouds, skies should be mostly sunny today. Despite this, strong cold air advection will allow highs to top out around 38. Winds will gradually weaken through the morning and afternoon hours, but breezy winds will produce wind chills in the upper 20s.

Clouds will increase this evening as the main upper level energy grazes the area. Also, a few snow flurries may be squeezed out between 5 and 8 p.m. Winds will pick up again between 5 p.m. and midnight with gusts up to 30 mph. Looking upstream, there is an extensive stratus deck behind the clipper system. These low clouds should slowly shift eastward with the movement of the trough. I think clouds will begin to break after midnight with mostly clear skies by sunrise. As a result, temperatures will be very cold tonight with lows around 25.

Snow Possible After Midnight

2010-02-14T17:26:00.003-06:00

A strong arctic cold front is currently approaching Northwest Mississippi with light to moderate rain falling across Arkansas and snow falling in the colder air across Missouri, Illinois, and Kentucky. This front will continue to push to the south and east tonight and should pass through the county between midnight and 1 a.m. Accompanying the front will be strong northwesterly winds with gusts possibly up to 30 mph. Some rain will occur ahead of the front before midnight, but the majority of the precipitation will be post-frontal. The precipitation after midnight will remain liquid for a few hours, but a changeover to snow appears likely once the true arctic air seeps in after 3 a.m. The snow will only last a few hours and should be to our east by 7 a.m. This event will feature an east to west gradient accumulation gradient instead of the north to south gradient we saw with Friday's event. I think western parts of the county (Moores Bridge and Elrod) will see a dusting, while communities in the eastern part of the county (Abernant) may see up to 2". For Tuscaloosa and Northport, I expect most areas to receive between a dusting and 1". This may result in a few slick spots on area bridges and overpasses, so use caution if you're heading to work or dropping the kids off at school in the morning. Bundle up because it will be a blustery and cold day with highs staying in the 30s.

Snow Winding Down

2010-02-12T14:50:00.004-06:00

The snow has been a beautiful sight to some today, but this event is beginning to wind down. All of Tuscaloosa County saw snow with a trace across the north and up to an inch across the south. In the cities of Tuscaloosa and Northport, the most common amounts I've seen are a dusting to a half an inch. A lot of the snow has actually melted this afternoon as temperatures have risen to 36. All of the snow should exit the county after 4 p.m. Although the road conditions are in good shape right now, I am worried about some icy patches developing on the roads after 7 p.m. as temperatures drop below freezing.

We'll see slightly warmer temperatures but still chilly tomorrow under mostly cloudy skies. Highs should be in the low to mid 40s. On Sunday, we'll quickly turn our attention to the north as a strong Clipper will approach the state late in the day. These systems typically are moisture starved, but there is decent agreement in the models that some light rain will arrive Sunday afternoon and may changeover to light snow late Sunday night through early Monday morning. Accumulations, if any, should be minor, but it's possible the roofs and tops of cars could be white when you wake up Monday morning. After the Clipper passes, arctic air will pour into the state with highs in the 30s Monday and Tuesday. The air mass will modify some by Wednesday with rebounding temperatures Thursday and Friday.

However, the moderation will be short-lived because strong blocking is forecast to shift into western Canada and Alaska by the end of next week in response to a tropically enhanced northern Pacific wave train. This will promote a highly amplified pattern with cross polar flow becoming established by next weekend. Needless to say, don't expect any prolonged periods of warmth anytime soon. In fact, I wouldn't be surprised if temperatures in the last half of February are even colder than the first half of February.

Let It Snow!

2010-02-12T11:15:00.004-06:00

Snow has fallen since about 8:30 a.m., but it has only begun to stick within the last hour. Many grassy areas and roofs are turning white, and this will only continue through the afternoon hours. The good news is that roads are okay right now, but that likely won't be the case by 2 p.m. The temperature is currently 33, and it should hit freezing within the next couple of hours. Please use caution if you'll be driving on area roads. It still appears as though the snow will end by 5 p.m. I'll have another update this afternoon.

Snow Day

2010-02-12T07:44:00.005-06:00

We managed to dodge any snow overnight as the precipitation above the surface was just not heavy enough to cause evaporative cooling. Don't let that fool you because it will snow today, and in fact, it should begin by 9:00 a.m. It's going to take a little work for the snow to stick because the current temperature is 37. Granted, when the snow does begin to fall, the temperature will drop. However, the snow may not be heavy enough to drop the temperature below freezing; I will be optimistic and forecast that we reach 32 around 11 a.m. To remain consistent, I'm not going to change my totals (see my post from last night for a map) as I still expect there to be more snow in the southern part of the county than the northern part. Some roads could be slick, particularly north and south of Tuscaloosa. Even in Tuscaloosa and Northport, some bridges could become slick, so use caution if you'll be on the roads today. The main adjustment to my forecast is that the snow will likely stick around through 5 p.m. as the back edge of the precipitation shield is lingering across southern Arkansas. I actually think we'll see some clearing skies after 8 p.m., which will allow temperatures to get rather cold tonight. Lows tomorrow morning will be near 24. Look for brief updates throughout the day.

Evening Thoughts

2010-02-11T20:59:00.006-06:00

A big snowstorm is underway just to our west across Texas, Arkansas, Louisiana, and Mississippi. In fact, almost 9" of snow has already fallen in Dallas. The leading edge of the snow has now reached as far east as Central Mississippi. Light radar echoes are visible across West Alabama, but the air in the lowest 5,000 feet is still too dry for any precipitation to reach the surface. The current temperature and dew point at the Tuscaloosa Airport are 41 and 23, respectively, so it's safe to say that we should not see any precipitation before midnight. Several hours of moistening the lowest part of the troposphere will allow thermal profiles to be supportive of light snow after 3 a.m. The large majority of the snow that accumulates before sunrise should be confined to grassy and elevated surfaces. However, it's possible that there could a few slick spots around the area tomorrow morning, mainly on bridges and overpasses. Be careful if you're heading to work. The good news for the youngsters is that Tuscaloosa City and County schools are closed tomorrow.

My thoughts have not really changed much regarding snowfall amounts. Due to strong upper level dynamics, a surface low is trying to develop across the western Gulf of Mexico about 150 miles east of Padre Island, TX. Pressure falls and thicknesses suggest the low should track eastward across the central Gulf through tomorrow morning. This lines up reasonably well with what the European has consistently shown for the last few days. An average of 1.5" seems to be a reasonable forecast for the area; up to an inch in the northern part of the county and possibly up to 2" in the southern part of the county. The cities of Tuscaloosa and Northport will probably be around 1.5" when the snow ends by 3 p.m.

Clouds Thicken, Slight Chance of Snow Overnight

2010-02-11T08:01:00.004-06:00

High clouds will thicken throughout the day as a storm system in Texas moves eastward into the Gulf of Mexico. The leading edge of the precipitation shield is approaching Northeast Louisiana, and this should remain off to our south and west through the daylight hours. It will be chilly again today as the cold dome of high pressure to our north refuses to relent its grip across the region. Highs should top out around 44 this afternoon. Overnight, synoptic scale lift will become more favorable for precipitation, but dry air in the lowest 5,000 feet will have to moisten up before any precipitation can reach the surface. As the rain shield approaches from Mississippi, it will take a few hours before any precipitation can reach the surface. However, the atmosphere should be sufficiently moistened after 3 a.m. for light snow to fall. Any snow that falls could stick on grassy and elevated surfaces, but the relatively warm concrete should prevent major travel issues through sunrise. Lows tomorrow morning will be near 31.

As expected for the past couple of days, the models have trended northward with the surface low. Given the consistency of the Canadian and European models, it's hard to discredit either one. I think the Global Canadian is still too far north, and in fact, the Canadian ensembles actually place the surface low very close to the European's track. Therefore, I think the European solution is the best way to go, and based on it, I have adjusted my snow totals upward slightly. I expect between 1-1.5" to accumulate in the city, but up to 2" may fall in the southern part of the county. Some roads may become slick tomorrow, so use caution if you have to drive to work. I won't be surprised to hear about area school closings tomorrow once the NWS issues a winter weather advisory.

Once this system exits, we'll begin to turn our attention to the north where cold air is poised to invade the state next week in the wake of a Clipper. I think the NWS highs next week are way too warm. I'll discuss that and the winter weather threat in more detail tomorrow morning.

High Clouds Return, Chilly

2010-02-10T08:00:00.004-06:00

A nice but chilly day is on tap as a cold dome of high pressure will be entrenched over the region. The sunny skies this morning won't last long as a band of high clouds associated with the southern branch of the jet stream will stream into the area throughout the day. It won't be cloudy, but there will be clouds overhead just about all day. Northwest winds flowing out of the surface high will be crossing a snow pack to our north, so temperatures will be chilly today with an afternoon high around 45. Winds will not be as strong as yesterday, but we may still have gusts up to 20 mph at times today. Additional high clouds will stream in overnight in advance of our next weather maker out in the Desert Southwest. Lows tomorrow morning will be near 27.

Now that the storm system in the Southwest U.S. has entered the North American upper air network, the majority of the models have come into agreement to suggest a very slight northward shift of the surface low. However, there is still not good agreement on the placement of the surface low. What is good news is that there is better agreement that the leading edge of the precipitation shield will extend further north. Regardless of which solution will be correct, the wetter solution suggests some precipitation will be possible on Friday. I think a compromise of the consistent Global Canadian and European models remains the best way to go. Based on this, I still think light snow is a possibility on Friday for our area, but the best chance will remain to our south. If I had to pinpoint exact totals at this time, I would forecast a dusting to a half inch. I'll have more thoughts on this again tomorrow.

Windy, Much Colder

2010-02-09T08:04:00.003-06:00

The heaviest rain across the state is well to our east, but light showers will continue to fall through 10 a.m. The cold front passed through the county just a short time ago, but the cold air is not far behind. When this cold air arrives, temperatures will begin to drop throughout the day and should be near 41 by noon and 37 by 5 p.m. The sunshine may return late this afternoon, but this will not be able to help temperatures, especially with west northwest winds crossing a snow pack across Arkansas. Speaking of winds, they will be strong today with gusts up the 25 mph, which will only make temperatures feel even colder this afternoon. The winds will only become stronger tonight with some gusts up to 30 mph possible before midnight. Mostly clear skies and dry air favor radiational cooling, but strong winds will keep the near ground layer mixed enough to prevent temperatures from plummeting. Lows tomorrow morning will be near 26.

The trend in the model guidance for Friday's storm system is southward. Although the pattern certainly favors a suppressed storm track, it just seems as though most models are a little too flat with the 500 mb pattern, including the European model. Many systems this year, particularly forecast by the GFS, have been too flat in their medium range solutions. The European is not typically as flat as the GFS, so this does lend some support for the GFS. However, the 00Z Canadian solution shows a slightly deeper system, which induces weak ridging downstream. This results in a low pressure track that is along the northern Gulf Coast. This solution seems to be more meteorologically sound, but it is worth noting that the Canadian is an outlier. I do think the global models will eventually shift back to the north again, but it probably won't be as far north as the Canadian.

So what does this mean for Friday's weather? There is a good chance for accumulating snows in Alabama. I still think the best chance of snow will be to our south, but even around Tuscaloosa, we still have a chance of seeing some light snow. I'll post any new thoughts I might have tomorrow morning.

Rain Arrives After Midnight

2010-02-08T08:04:00.003-06:00

The million dollar question in today's forecast is whether or not we will see the sun. Low clouds have stubbornly persisted across the area all weekend, and it looks like they may hold tough this morning. What will likely break up the clouds will be a developing storm system in West Texas. This will cause a cold surface high to shift to our east and allow southeasterly winds to commence late this morning. Vertical mixing should gradually break up the low cloud deck after noon. However, additional clouds streaming eastward in advance of the storm system in Texas will not allow much in the way of sunshine today. Based on this scenario, highs should top out around 51. If the low clouds don't break up today, highs will stay in the upper 40s. By this evening, the low pressure across Texas will move to the east northeast and should be located in southwest Alabama around sunrise tomorrow morning. Light rain should spread into the state after midnight and become heavier after 3 a.m., but total rainfall amounts should generally be near a half inch. The rain will stick around through sunrise but should be light in intensity. Lows tomorrow morning will be near 45.

Today will likely be the warmest day of the week as modified arctic air pours into the state. I'll be keeping a close eye on a storm system at the end of the week. The pattern supports a very favorable storm track for accumulating snows in Alabama on Friday. At this time, the best threat for snow may actually be to our south, but there's no question that all the players are on the field.

Cool, Damp

2010-02-05T08:02:00.005-06:00

Other than a few lingering showers across the eastern part of the county, all other areas are dry. These showers should exit to the east shortly, and we'll remain relatively dry for the remaining daylight hours, although, there may be some drizzle. Temperatures won't rise much today with highs topping out near 51, and temperatures may actually begin to drop slowly after noon as a colder air mass begins to move in. A tight pressure gradient will ensure a breezy day with gusts up to 25 mph. The upper level energy will rotate through tonight, so there will likely be some additional showers between 7 p.m. and midnight. Strong west northwest winds will create very window conditions after midnight with some gusts up to 30 mph. Lows tomorrow morning will be near 39.

Saturday will be cold with morning drizzle and highs in the low to mid 40s. We may finally see the sunshine return Sunday afternoon with highs in the mid to upper 40s. Temperatures will warm up briefly Monday and Tuesday ahead our next storm system. An glancing blow from an arctic air mass arrives by Wednesday and will result in temperatures below normal for the remainder of the work week.

Wet, Cool

2010-02-04T08:07:00.003-06:00

It will be a wet 24 hours as a surface low moves out of the Gulf of Mexico, and most communities around the area will receive over an inch of rain. Light to moderate rain will continue to fall this morning, and the rain will become heavier this evening as the strongest forcing approaches the area. Temperatures will be chilly today with an afternoon high around 48. Temperatures will actually begin to rise after midnight as the surface wave advects warmer air into the area. The temperature will actually rise to and remain steady at 54 through sunrise. The rain should begin to decrease in intensity off after 2 a.m., but it will still be a wet commute to work and school tomorrow morning.

Dry, Clouds Stream In

2010-02-03T08:07:00.003-06:00

We should be able to sneak in one more dry day before a developing storm system in Texas ejects eastward. The fringe of this system already extends into our area with some high clouds moving through. Additional and thicker clouds are located across Louisiana and those should push into the state later this afternoon. A surface high over the Great Lakes and an organizing area of low pressure across Mexico will allow winds to veer around to the northeast. This should keep us slightly cooler today than yesterday with highs topping out near 57. Clouds will continue to thicken and lower this evening and overnight. There is a very slight chance of see rain moving into the area before sunrise, but I think we should remain dry as the leading edge of the precipitation will be just to our south and west. Lows tomorrow morning will be near 40.

Some Clouds, Comfortable

2010-02-02T08:02:00.003-06:00

Punxsutawney Phil did not see his shadow this morning, so that means six more weeks of winter. Our weather certainly won't feel winter-like today once we get rid of the low clouds that are currently in place. This will occur later this morning and early afternoon as low-level moisture becomes scoured out by a departing shortwave trough. This will leave us in a zonal flow aloft, which should promote temperatures slightly above normal today. A few clouds will likely stick around through this afternoon, but enough peeks of sunshine should boost highs near 58. Skies will be partly cloudy overnight, but it seems as though moisture will increase in the lowest 1,000 feet after midnight. This should allow skies to become increasingly cloudy. Still, lows tomorrow morning will still dip down to 31.

The groundhog doesn't have the most stellar forecast track record, but I think he may be on to something this year. The global pattern definitely supports a return to very cold air over the next couple of weeks as pressures continue to build across the high latitudes of the Northern Hemisphere. A strong stratospheric warming event is beginning near the pole, and this will only enhance the air mass across Siberia and northwestern North America. I don't think the duration of the cold will be as long as what we saw in the first half of January, but I won't be surprised to see some record-breaking temperatures by the time February ends. Adding fuel to the fire is an active subtropical jet stream that should become even more established in the next 10-14 days. These factors argue for a cold and stormy period down the road.

Increasing Clouds, Warmer

2010-02-01T07:57:00.003-06:00

After a cold start to begin the work week, temperatures are warming quickly into the 30s. It appears that there will be a window of opportunity this morning for temperatures to continue warming unimpeded, but clouds will be on the increase this afternoon in advance of a weak upper level shortwave. Still, it will feel much warmer as highs rebound up to 56 this afternoon. Clouds will continue to thicken and lower as we go into the evening and overnight hours, and there may even be some light showers before midnight. Lows tomorrow morning will be near 37. Our next chance of rain arrives on Thursday, but it should exit by the weekend. The weekend looks like nice but cool.

Wet, Cooler

2010-01-29T08:13:00.006-06:00

Rain will return to the area today as a storm system currently along the Upper Texas Coast moves eastward along the Gulf Coast states. After several days of following this system and the synoptic scale pattern, the surface low pressure should track from near Houston to Andalusia, AL over the next 24 hours. A large band of precipitation extends from the northwest Gulf of Mexico to Missouri with wintry precipitation generally falling along and north of I-40. Some showers are moving into West Alabama, and we could see some light rain to moderate rain at times this morning. The heaviest rain should arrive after 6 p.m. and last through midnight. Highs will only top out around 46 this afternoon due to the presence of clouds and rain. However, once the low pressure wave approaches the southwest corner of the state, temperatures should actually rise to around 48 just after midnight. Light rain will continue through the overnight hours with temperatures dropping to 45 tomorrow morning. I should also mention that winds will be breezy at times this afternoon and overnight as the pressure gradient tightens.

The tough part of the forecast hinges on the chance for any wintry precipitation as the system exits. I still think that temperatures will drop quickly once the arctic air moves into the area early tomorrow afternoon. Some lingering precipitation associated with the upper level energy should move through the area by Saturday night. I think temperature profiles will support a threat for very light freezing rain or freezing drizzle between 5 p.m. and 11 p.m. Precipitation amounts will be so light that major travel problems should not be a concern. However, some patchy ice will be possible on area bridges, so use caution if you'll be out tomorrow evening. The warmest part of the day tomorrow will be the early morning hours with temperatures dropping throughout the day. We'll dry out on Sunday, and the sun should return in the afternoon. I still think temperatures on Sunday are forecast to be too warm by the models, especially with northwest winds crossing a snow and ice pack to our north. Look for highs to be around 40 on Sunday. The large majority of next week looks rather dry with temperatures near normal, but we should return to an active weather pattern late next week.

MOS Watching in Memphis

2010-01-28T19:18:00.003-06:00

Yesterday, I picked three cities in the northern and central Plains to follow for lows Thursday morning, highs Thursday afternoon, and lows Friday morning. I want to get a handle on how MOS and raw guidance handle the arctic air mass. So far, model guidance has not busted as bad as I thought it would. Granted, today's high in Kansas City was definitely lower than any of the guidance suggested. Areas further south and east across Missouri and northern Arkansas were consistently 3-5 degrees cooler today than what MOS products were forecasting yesterday.

The further south you go, MOS products will likely have similar or even worse errors because this arctic air mass is a statistical anomaly. Although this air mass is much colder than normal for cities like Omaha and Des Moines, the MOS products should have plenty of these cold anomalies incorporated into its records. In other words, it's much more common for these cities to have cold outbreaks during the middle of winter. On the other hand, cold outbreaks are less common across the South, and there aren't as many of these anomalies built into the MOS records. As a result, look for MOS products to struggle with this arctic air mass across the Mid South. I'll add Memphis to the end of this list, and we'll see how well the models perform tomorrow.

Omaha, NE
12Z NAM MOS -- 2/13/3
12Z GFS MOS -- 3/14/4
18Z NAM RAW -- 3/14/5
18Z GFS RAW -- 4/14/5
Thursday morning low: 5
Thursday afternoon high: 14

Des Moines, IA
12Z NAM MOS -- 3/11/0
12Z GFS MOS -- 2/10/-1
18Z NAM RAW -- -2/11/8
18Z GFS RAW -- 0/9/-5
Thursday morning low: 3
Thursday afternoon high: 12

Kansas City, MO
12Z NAM MOS -- 13/25/8
12Z GFS MOS -- 13/28/14
18Z NAM RAW -- 16/26/16
18Z GFS RAW -- 17/24/16
Thursday morning low: 15
Thursday afternoon high: 23

Memphis, TN (forecast for Friday afternoon high)
12Z NAM MOS -- 42
12Z GFS MOS -- 36
12Z NAM RAW -- 34
12Z GFS RAW -- 30
I think the raw guidance is on the right track for Memphis, but the MOS products should bust badly on the high. It will be interesting to watch what happens.

Partially Sunny, Mild

2010-01-28T08:15:00.004-06:00

Our next weather maker is spinning over the Four Corners this morning with a healthy shield of precipitation affecting Texas and Oklahoma. The good news is that any rain should stay well to our west and north for the next 24 hours. A few high clouds associated with this storm system have blanketed the area this morning, and it appears that we'll be stuck with these throughout the day. However, the cirrus clouds should be thin enough to allow for filtered sunshine. Highs should manage to top out around 61 this afternoon. Enjoy today because this will likely be the warmest weather we see for at least a week. Clouds will thicken and lower through the evening and overnight hours. However, cool northeasterly winds will still allow temperatures to drop near 39 tomorrow morning.

There is still some uncertainty regarding the storm system poised to affect the area on Friday and Saturday. What is not in question is that 98% of the precipitation that falls will be liquid, but the remaining 2% of the precipitation could end as light freezing rain or freezing drizzle. I still think the models will be a little too warm with the arctic air mass moving in, so I think there will be a brief window of opportunity for some very light freezing rain/drizzle to occur on Saturday morning. Although the amounts will be light, there may be some slick spots on area roadways. I'll have a more extensive discussion on these threats tomorrow morning.

MOS Watching

2010-01-27T22:30:00.002-06:00

I've picked three cities in the northern Plains to follow for lows Thursday morning, Thursday afternoon highs, and Friday morning lows. I want to get a handle on how MOS and raw guidance handle the arctic air mass. I'm willing to bet that MOS guidance will be too warm with the temperatures as it rarely performs well with these arctic air masses.

Omaha, NE
12Z NAM MOS -- 2/13/3
12Z GFS MOS -- 3/14/4
18Z NAM RAW -- 3/14/5
18Z GFS RAW -- 4/14/5

Des Moines, IA
12Z NAM MOS -- 3/11/0
12Z GFS MOS -- 2/10/-1
18Z NAM RAW -- -2/11/8
18Z GFS RAW -- 0/9/-5

Kansas City, MO
12Z NAM MOS -- 13/25/8
12Z GFS MOS -- 13/28/14
18Z NAM RAW -- 16/26/16
18Z GFS RAW -- 17/24/16

Sunny & Breezy

2010-01-26T07:59:00.004-06:00

High pressure at the surface will dominate our weather today. We'll see an abundance of sunshine, but temperatures will be slightly cooler than yesterday. Highs should top out around 54 this afternoon. A tight pressure gradient will remain in place today and result in another windy day with some gusts up to 30 mph. The pressure gradient will relax substantially overnight as high pressure will be centered over the area. With very light winds, dry air, and clear skies in place, temperatures should easily be able to drop below freezing tonight. Lows tomorrow morning will be near 28.

Temperatures will temporarily warm up Wednesday and Thursday before our next storm system arrives on Friday. We'll have to watch this system closely for the threat for winter weather as the weather pattern favors a suppressed storm track. Combined with a surge of modified arctic air, the potential is in place for a significant winter storm across the South. I think our area will remain all rain except for a brief changeover to freezing rain at the end of the event. However, I think residents in North Alabama should prepare for some major headaches. Much colder air will filter into the state for the weekend, and highs will stay in the 30s Saturday and may struggle to break 40 on Sunday as strong northwest winds will blow over a snow and ice pack.

Cooler and Breezy

2010-01-25T08:02:00.003-06:00

The sun has finally made a return appearance this morning now that most folks have to return to work or school. The surface storm system that brought us the windy and stormy conditions yesterday is exiting to the east, but its upper level counterpart is still located to our north. This should not have a noticeable impact on sensible weather today, but the cooler air mass that filtered into the state in the wake of yesterday's frontal passage will allow for more seasonable temperatures this afternoon. Mostly sunny skies should allow for highs to top out around 55 today. It will also be windy as a tight pressure gradient remains in place, and winds could gust as high as 30 mph at times this afternoon. The aforementioned upper level disturbance will move through the area tonight, and it will provide a reinforcing supply of cooler air. A few low clouds may accompany the disturbance, but the majority of the night will feature mostly clear skies. Also, winds will remain up through the night, which should inhibit ideal radiational cooling conditions. Still, it will be chilly tomorrow morning with lows near 33.

Mostly Cloudy, Slightly Cooler

2010-01-22T08:06:00.003-06:00

Skies remained clear for most of the night, but a stratus deck has moved into the area from the north. It appears that these low clouds will hang out for most of the day in some capacity. We could see some peeks of sun this afternoon, but the clouds will certainly dominate. The front that moved through yesterday will provide a temporary cool down from the last couple of days. Highs should top out around 60 this afternoon. Our weather pattern will quickly change again tonight as our next storm system takes shape over the western High Plains. Leeside cyclogenesis will allow southeasterly winds to return overnight, and a few cirrus clouds in advance of the storm system will approach the area before midnight. This should prevent ideal radiational cooling, but temperatures tomorrow morning will be near 45.

Our recent thaw will come to an end by the time the weekend is over. The big storm system out West will allow for two more warm days with highs in the 60s Saturday and Sunday. A chance of rain and possibly some thunderstorms will arrive late Saturday night and early Sunday morning. I was initially concerned about the chance for severe weather, but the occlusion of and the timing of this system should prevent those concerns. Strong dynamics but weak thermodynamics should allow for a forced line of storms to develop. These storms may produce some strong winds early Sunday morning. A cold front should pass through Sunday afternoon, and a much cooler and drier air mass will engulf the state. Cooler than normal temperatures will dominate early in the week followed by near normal temperatures late next week. The pattern for the next couple of weeks doesn't suggest any prolonged periods of anomalously warm weather.

Mostly Sunny & Warm, Isolated Storms Possible

2010-01-21T08:04:00.006-06:00

We managed to avoid any severe weather, but a good soaking rain fell yesterday and overnight across the county with most areas receiving between 1 and 1.5". The rain and storms are quickly exiting the exit as a strong dry slot is punching into the state. This dry slot is allowing for a good supply of sunshine this morning, but a few low clouds will move through later this morning and early afternoon. The cold front associated with this storm system is still located along the Mississippi River and won't pass through the county until after 7 p.m. As a result, temperatures will remain unseasonably warm with highs topping out around 73 this afternoon. As the front approaches this afternoon, it could spark off some isolated storms as SBCAPE values climb to almost 1,500 J/kg. Damaging winds and large hail will be the primary threat with any storms that form. It will also be breezy with winds gusting up to 25 mph this afternoon. As the front swings through, slightly cooler and drier air will filter into the state. However, a chance of showers will remain possible through midnight as the upper level energy moves through. Skies will likely become cloudy tonight but clearing near sunrise. Lows will be near 46 tomorrow morning.

Some Clouds, Mild

2010-01-19T08:09:00.004-06:00

Mostly clear skies overnight allowed temperatures to drop well into the 30s. Clouds have been on the increase this morning in advance of a subtle upper level disturbance and within a weak warm air advection regime. A lead shortwave ejecting out of the Four Corners has initiated the development of a lee side cyclone across eastern Colorado. As the day progresses, this low will consolidate its energy across the Oklahoma and Texas Panhandles and slowly move northeastward. Southerly winds in advance of the low and on the western periphery of a surface high to our east will result in a southerly breeze today. This should allow highs to top out around 63 this afternoon despite partly cloudy skies. Thickening clouds and a persistent southerly breeze will keep temperatures unseasonably mild tonight with a low near 51. With some lift present overnight and increasing moisture, there is a very small chance of rain before sunrise, but I think we'll stay dry.

The big weather maker this weekend still appears to have some potential to produce severe weather across the region. As is the case with the large majority of cool season severe weather events, this event will have plenty of dynamics to work with, but the thermodynamics will be lacking. Still, it appears that enough instability will be present to warrant a threat of severe weather on Sunday.

Mild Week Ahead

2010-01-18T08:04:00.003-06:00

The rains over the weekend have lead to widespread dense fog around the county this morning. Satellite imagery and forecast soundings suggest the fog should begin to mix out by 10 a.m. After the fog dissipates, a beautiful day is in store with abundant sunshine. After a cool day yesterday, temperatures will be over 10 degrees warmer this afternoon with highs topping out around 62. Skies will be clear this evening but will begin to increase late tonight in advance of an upper level disturbance. This upper level disturbance is evident on water vapor imagery and is currently impacting the southern Plains. All available guidance keeps this disturbance well to our north, but a few clouds will move across the area as its southern fringe clips us. Lows tomorrow morning will be near 41.

We'll be in a very progressive pattern this week meaning that we'll see rain every 2-3 days. However, temperatures will be above normal, and it's not out of the question that we could jump into the 70s at some point by the end of next weekend! Thursday or Sunday would be the best bet for that to happen. When it gets warm in January, we usually have to start worrying about severe weather, and that may very well be the case late this weekend as a lot of energy ejects of out the West. It's a little early to talk about specifics, but pattern recognition certainly supports the threat for severe weather. I'll have more on this each day this week.

Beautiful Day On Tap

2010-01-15T08:08:00.005-06:00

Less in the way of cloud cover than I expected has lead to another chilly start, but temperatures are quickly rising into the 30s this morning. Most of the day will be sunny, but a few cirrus clouds moving from the south may encroach on the area by later this afternoon. These high clouds will be the first indication that our weather will be changing in the next 24-48 hours. Indeed, a storm system moving into the Gulf of Mexico will affect South Texas and the extreme northern Gulf coast today, but we should remain dry through sunrise tomorrow morning. Highs will top out around 59 this afternoon. Clouds will thicken and lower as we go into the evening and overnight hours. Along with a light easterly wind, temperatures should remain above freezing for only the second time so far this year. Lows tomorrow morning will be near 40.

A pretty good soaking is likely tomorrow with the majority of the precipitation occurring from the late morning hours through early Sunday morning. If you're headed to Bryant-Denny Stadium to celebrate the Crimson Tide's national championship, be sure to take an umbrella or poncho because it will be wet. Highs will stay in the 50s Saturday and Sunday. Our warm pattern will remain in place next week, but an active subtropical jet promises to bring more rain and possibly thunderstorms to the area next week.

Winter Thaw Begins

2010-01-14T08:07:00.005-06:00

A much warmer pattern looks to lock in through the extended forecast period as the westerlies associated with the polar jet are located across the northern U.S. The subtropical jet will remain active over the southern U.S., so it's not likely we'll get tremendously warm. High pressure to our east will allow for a southerly flow to develop today, which should allow for an increase in lower level moisture. Moisture began increasing in the mid-levels last night as evident by the spotty cloudy cover across the region. This mid-level moisture should remain in place today and will lead to partly cloudy skies. This will keep temperatures from reaching their maximum potential, but we should still top out around 55. Clouds should thicken and lower some this evening and overnight as moisture continues to increase. Lows tomorrow morning will be near 29. Tonight's freezing temperatures will probably be the last we see for at least 10 days.

Abundant Sunshine, Warmer

2010-01-13T07:56:00.003-06:00

After a chilly start this morning, we'll see a nice rebound in temperatures as a shortwave ridge builds across the region. Subsidence associated with the ridge will allow for an abundant supply of sunshine, which will propel highs to near 51 this afternoon. Tonight's forecast would be relatively straightforward if it weren't for some weak upper level energy approaching from Texas. There may be just enough moisture for a few clouds to develop after midnight, and this would disrupt ideal radiational cooling conditions. Lows tomorrow morning will be near 25.

A.M. Clouds, Cool

2010-01-12T08:11:00.003-06:00

A cold front that passed through early this morning brought a reinforcing shot of polar air to the region. This air mass is much warmer than the arctic air mass we dealt with late last week and this past weekend. Most people probably got a little spoiled by highs in the upper 40s yesterday, but we'll be several degrees cooler today. A few low clouds may pass through this morning, but the majority of the day should be sunny. Highs will top out around 43. Very weak warm air advection will commence tonight as an upper level ridge begins to build across the region from the west. However, mostly clear skies, dry air, and light winds will support a strong radiational cooling. Lows around 20 tonight will be the coldest we'll feel in the foreseeable future.

Warming Up

2010-01-11T08:22:00.004-06:00

After a frigid morning low of 13, temperatures are quickly rising into the upper teens. Skies should be sunny for the majority of the day as northwesterly flow aloft and surface ridging dominate. This will allow temperatures to rebound nicely this afternoon with highs around 44. Westerly winds may be breezy at times this afternoon with gusts in the upper teens. By this evening, an upper level shortwave and surface cold front will be approaching from the north. In advance of this system, a few high clouds will pass through, but I don't expect any precipitation since the air is extremely dry. Some lower clouds may develop after the front passes through the area around 3 a.m. Lows tomorrow morning will be around 24.

A Few Clouds, Very Cold

2010-01-08T08:10:00.003-06:00

The arctic front that swept through the area yesterday afternoon is being felt in full force this morning. Temperatures are running around 17 with strong winds and clouds, which speaks volumes to the strength of this air mass. Speaking of strong winds, a tight pressure gradient is creating wind chills just above 0 this morning. Winds should slowly subside as we go through the day, but wind gusts will still consistently remain over 15 mph and make temperatures feel even colder. An approaching shortwave will push through the area today and will produce a few low clouds. At the same time, an active subtropical jet will be screaming over the region and will produce a band of cirrus clouds. Despite the lower and upper level clouds, there will still be a few peeks of sunshine. However, the combination of clouds, a snow pack to our northwest, and the arctic air overwhelmingly support undercutting guidance today. Expect highs to top out around 27 this afternoon. We should be mostly clear tonight, but a few clouds may continue to stick around. With lighter winds and less cloud cover than this morning, temperatures will be likely be near 14 tomorrow morning. If you're heading to the airport to greet the Alabama football team this evening, dress in layers because temperatures will be in the lower 20s for the arrival of the first flight and the upper teens for the second flight.

Afternoon Forecast

2010-01-07T12:19:00.004-06:00

Big changes to the forecast are needed. Although radar echoes showed what appeared to be snow for much of this morning, very dry air in the lowest 5,000 feet was evaporating the snow before it reached the ground. After enough moistening, we finally saw decent burst of moderate snow mixed with sleet and rain in the Tuscaloosa area around noon. The snow and sleet briefly accumulated on elevated surfaces before melting. It's evident that the wave along the approaching arctic front has pulled slightly warmer temperatures aloft into our area and caused total melting of ice crystals. It's also clear that ground temperatures are too warm to support much in the way of accumulating snow without a sustained heavy burst. There is still another band of mixed precipitation moving into the western part of the county, but it should end by 2 p.m. Additional bands of precipitation are ongoing across Mississippi, and these should provide a few brief periods of light rain or snow through 5 p.m. The vast majority of the county will see little or no accumulations of snow. It would still be a good idea to use caution if you'll be traveling on roadways late this afternoon and evening as there will likely be some slick spots.

Snow, Turning Much Colder

2010-01-07T08:04:00.003-06:00

The much anticipated winter weather threat has arrived but not without an early surprise. Temperatures overnight bottomed out at 24 before 3 a.m., but they have actually risen to near freezing now. This warming is due to a wave along an approaching arctic front that stretches from central Indiana to northwest Louisiana. However, the snow flurries that are currently falling across the county should prevent a significant northward surge of the warm bubble of temperatures evident across central Mississippi. Without the snow falling, temperatures would probably rise into the upper 30s as the wave along the front gets closer. It doesn't appear as this current batch of snow will be continuous, and as a result, temperatures will still probably top out near 35 late this morning. More importantly, the snow flurries falling will help to moisten and cool the lowest 5,000 feet of the troposphere as we go through the morning hours.

A more concentrated area of precipitation is ongoing across central Mississippi and this should spread eastward over the course of the day. There may be some sleet mixed with the snow flurries this morning, but I think the overwhelming majority of this event should be all snow. The main snow event should begin after 11 a.m., but accumulations likely won't occur until after noon. I still expect up to an inch of snow to fall around the county. Roadways will likely become slick this afternoon, so please use caution if you'll be traveling. The arctic front should plow through the area after 3 p.m. with snow continuing to fall through 6 p.m. After the snow exits, temperatures will begin to plummet as the arctic air infiltrates the state. In fact, temperatures will fall to near 20 by 11 p.m. Compounding matters will be a tight pressure gradient that will setup late tonight through tomorrow morning. This pressure gradient will allow winds to gust up to 25 mph very early Friday morning, which will put wind chills into the single digits at times. With a fresh snow pack in place, lows tomorrow morning will be near 14.

Winter Weather Advisory Issued

2010-01-06T16:02:00.004-06:00

The NWS in Birmingham has issued a winter weather advisory for Tuscaloosa County until Thursday at 9 p.m. I have no major disagreements with their forecast at this time. I still think that sleet will begin around 10 a.m. and then change over to all snow after 11 a.m. Most places around the county will average around an inch (slightly less south and slightly more north) of snow before it ends around 6 p.m. Roads will likely become slick tomorrow afternoon so use extreme caution if you have to travel. Kudos to school officials for making an early decision to close all area schools tomorrow. I wouldn't be surprised if classes are canceled Friday as well.

Increasing Clouds, Slightly Warmer

2010-01-06T08:04:00.004-06:00

Light winds have allowed temperatures to drop into the mid teens again this morning. Today will easily be the warmest day of the the next five days, but it will still remain on the chilly side. The arctic air mass currently in place began modifying yesterday and will continue to do so today. Also, a clipper coming out of Canada will swing southeast today and will contribute to a slight increase in temperatures throughout the troposphere. The majority of the day should be sunny, but a few high clouds may arrive early this evening. Highs should be able to top out around 39 before any clouds arrive. Tonight may be the warmest night for almost a week due to an increase in cloud cover and a weak southerly wind component developing. The clipper will swing closer towards the region, but I feel like any precipitation should hold off until after sunrise tomorrow morning. The low will be around 25 in the morning.

It still looks like we'll see some snow tomorrow, but there may be a brief period of some sleet mixed in at the onset of the event. The sleet may begin after 10 a.m. tomorrow morning, but I'm expecting the bulk of the precipitation to affect the area from 11 a.m. to 4 p.m. As is usually the case with these clippers, there won't be a ton of moisture associated with it. However, I think we stand to see up to an inch of snow once all is said and done. As a result, roads may become slick tomorrow afternoon so be careful if you have to do any traveling.

Sunny, Continued Cold

2010-01-05T08:13:00.002-06:00

It's bitterly cold this morning if you've stepped outside for any time as temperatures are running in the mid teens. We'll be on the subsident side of an upper level trough today which should yield an abundant supply of sunshine. It will remain cold as a slowly modifying arctic air mass remains in place, but we should at least warm above freezing this afternoon. Indeed, highs should top out around 35, but breezy northwest winds will make the temperature feel even colder at times. We should be thankful that winds have caused enough mixing at night to prevent temperatures from bottoming out. Tonight, however, it does appear that winds will be more calm than we've seen the last few nights. As a result, lows will be similar to this morning as we'll start the day with a temperature around 17.

It's looking more likely that we'll see some snow on Thursday, but the bigger story will be the dangerous cold that will invade the state Thursday night through Sunday. It's too early to forecast specific snow amounts, but it seems possible that we could pick up 1-2" of snow on Thursday. After the passage of the clipper, temperatures will plummet, and we should remain below freezing for close to 72 consecutive hours. Lows on Saturday and Sunday morning may be in the single digits. To add insult to injury, wind chills at some times between early Friday morning and late Saturday morning may be below 0! We should finally see temperatures return to normal late next week.

Cloudy and Cold

2010-01-04T08:15:00.003-06:00

Despite cloudy skies, temperatures are still running in the mid 20s this morning. An upper level disturbance moving through the northwest flow aloft generated an impressive looking area of snow on radar. However, very dry air near the surface has only resulted in a few snow flurries being observed across the county. Some additional flurries will be possible through the late morning hours. The cloud cover looks to stick around for much of the day, but we may see a few peeks of sun late this afternoon. Highs will top out around 34 this afternoon, but breezy northwest winds will make it feel even colder. By this evening, skies will become clear as very dry air will be in place. Once again, however, wind speeds will remain around 5 mph, which will prevent ideal radiational cooling. Even with the winds remaining up, the strength of this air mass will result in lows around 16 tomorrow morning.

I'm still closely watching the potential for snow on Thursday. Model discrepancies remain an issue, but there will be a winter storm somewhere in the Southeast late this week. After the storm exits, the coldest air in several years will infiltrate the region and could bring widespread single digit lows to the state. For those looking for any relief from the cold, don't despair because there may be some hope by the middle to late part of next week. It looks like the pattern may temporarily support highs back near normal.

Mostly Sunny, Breezy, & Much Colder

2010-01-01T08:20:00.006-06:00

A few light showers occurred overnight, and temperatures are chilly again this morning with temperatures near 40. We'll be on the convergent side of an exiting upper level trough, and as a result, we should have to a chance to dry out for several days. The dry weather will come with a price though. That price will be the coldest air of the season, which is poised to invade the state tonight and may last for at least a week. In the meantime, skies are partly cloudy this morning, but a few more clouds may pass through later this morning. Once the clouds pass to our south, the afternoon should feature an abundance of sunshine. With weak cold air advection and NNW winds coming off a snow pack to our north, highs won't rise much today. In fact, we'll only top out around 44 this afternoon. Winds may gust over 20 mph today, and this will make temperatures feel even colder.

Skies will be clear tonight and the air will be very dry with dew points dropping into the upper teens by sunrise tomorrow morning. The only negative factor for ideal radiational cooling will be winds remaining between 5 and 10 mph through the morning hours. However, upstream observations this morning show that lows are colder than what was forecast by MOS guidance yesterday. Therefore, I'm going to undercut guidance and forecast a low of 26 tomorrow morning.

The weather to start the new year will feature highs and lows at least 10-15 degrees below normal. While that's not exactly record breaking, the duration of the cold period will be impressive. We'll also have to watch late next week for the potential for a winter storm. A strong upper level short wave will drop southward out of Canada and will set the stage for some accumulating snow across the Deep South. This is still almost 6 days away, but there is general agreement on the upper air pattern next week. This pattern would certainly support a high likelihood for snow somewhere in the region, but subtle timing and placement differences of the upper air features preclude a high confidence forecast for a more specific threat area. Nevertheless, this will be something to watch closely over the next several days. After the passage of the late week storm system, even colder air will likely invade the region for the following weekend.

Cloudy, Slightly Warmer; Rain Possible Overnight

2009-12-31T08:17:00.003-06:00

The storm system that brought some light rain to the area yesterday and last night is exiting to the east. However, we'll quickly turn our attention back to the west where a strengthening shortwave trough is causing rain and snow across Oklahoma and the Texas Panhandle. In the meantime, since we are between two weather systems, we should remain on the dry side for the daylight hours. The morning sounding from Birmingham indicates that the air is very dry above 750 mb, but an abundance of moisture is trapped below. Although we'll continue to dry out the mid and lower levels as the day progresses, moisture will remain trapped below about 900 mb. As a result, skies will likely stay cloudy today. However, southerly winds will allow temperatures to top out around 54 this afternoon.

As the aforementioned shortwave approaches from the west, moisture will begin to increase through the column this evening and overnight. Heavier rains in the northern Gulf will tend to cut off the shield of rain to its north. As a result, a few light showers will be possible after midnight, but rainfall amounts will be very light (<0.05"). The precipitation should remain all liquid as forecasting soundings show that it will be a little too warm in the lowest 2,000' for any snow. As winds turn northerly this evening, temperatures will begin to drop quickly. Lows on the first day of the new year should be near 37. Wind gusts in the upper teens will make the temperature to feel even colder.

Rain Arrives This Afternoon

2009-12-30T08:11:00.002-06:00

Extensive cloud cover associated with our next weather maker kept temperatures 10-15 degrees warmer than the previous two nights. The aforementioned weather maker is a shortwave trough that will initiate the development of a surface low in the Gulf of Mexico later today. This low will slide eastward along the northern Gulf coast, and it will spread a shield of rain across the area this afternoon and evening. Although a few peeks of sunshine have been visible this morning, expect skies to become completely cloudy within the next couple of hours. Before the rain arrives, highs should be able to top out around 50. Winds will also be breezy at times today with gusts in the upper teens. After the onset of the rain this afternoon, temperatures will likely drop a few degrees. However, winds are forecast to turn to the south overnight, and temperatures may actually rise after midnight. In fact, lows tomorrow morning will be near 47. Although the main axis of rain will shift to our east by midnight, some sprinkles or drizzle will be possible overnight.

Sunny, Breezy, & Cool

2009-12-28T08:26:00.003-06:00

It's very chilly this morning with temperatures running in the lower 30s, but gusty northwest winds are making the temperature feel much colder. A strong surface high to our west will dominate our weather over the next 24-48 hours. A deepening upper air trough over the northeast U.S. will provide a reinforcing shot of Canadian air today. Despite full sunshine today, highs will only manage to top out near 45. Additionally, wind gusts in the upper teens will cause temperatures to feel 5-10 degrees colder at times today. By this evening, winds will begin to subside, and with clear skies, temperatures should quickly drop. The only negative factor for ideal radiational cooling will be the development of a few low clouds after 2 a.m. Still, lows tomorrow morning will be near 26.

Wet & Windy

2009-12-24T08:09:00.004-06:00

As advertised, a very strong cold front will approach the region today and create a very wet and windy day. The cold front currently stretches from Texarkana, AR southward to the Sabine River Valley in Texas. Very heavy showers and embedded severe thunderstorms are located ahead of the front across Arkansas and Louisiana. As the day progresses, this shield of precipitation will slowly move eastward. Rain chances for our area will begin to ramp up after noon, but the heaviest rain should hold off until this evening. We should see some broken cloudiness this morning, but cloud cover will only increase as we head into the afternoon hours. Highs should top out around 62 this afternoon. As a result of a tight pressure gradient, very strong southeasterly winds could gust as high as 40 mph late this afternoon and evening! Be very careful if you're driving a high profile vehicle, particularly along I-20/59 and I-65 between Montgomery and Mobile.

The heaviest rain and strongest thunderstorm activity should occur after 6 p.m. The main brunt of the rain should end by 11 p.m., but additional showers will be possible overnight as the upper level disturbance pivots across the region. In addition to strong winds, thunderstorms could be another potential hazard tonight. Although wind shear will be extremely favorable for severe weather, the very limited buoyancy (MLCAPE ~200 J/kg) will not be able to compensate for the shear. As a result, storms should be sheared apart. However, given the strength of the shear, a dynamically forced line of storms could be on the strong side. I think the severe activity will remain to our south and west. The cold front should pass through the area after midnight with temperatures quickly dropping into the 50s and 40s. The low tomorrow morning should be near 44.

Christmas Day is shaping up to be cloudy, drizzly, windy, and very cold. The warmest temperature of the day will be at midnight, but the afternoon high tomorrow will be in the lower 40s. Gusty west winds will make the temperature feel much colder all day. Additionally, some lingering moisture associated with the upper level disturbance will squeeze out some drizzle in the morning hours. Although some outlets are suggesting a chance of snow flurries tomorrow, I don't see this since there will be very meager moisture in the snow growth region. I would like to wish you and your family a Merry Christmas!

Mostly Cloudy, Slight Chance of Showers

2009-12-23T08:34:00.002-06:00

A big weather maker will be taking shape across the Plains states today, and this will slowly work its way eastward over the next 24-36 hours. A very slight chance of rain will be possible this afternoon, but most places should remain dry across west Alabama. Highs will top out around 60 despite the extensive cloud cover in place. A slight chance of rain will be possible overnight, but the most concentrated area of showers and thunderstorms will remain across Mississippi through sunrise tomorrow morning. The low should be near 52 tomorrow morning. Christmas Eve looks very wet, but I don't expect much in the way of severe weather at this point.

High Afternoon Clouds, Mild

2009-12-22T08:26:00.003-06:00

It's another cool morning with sub-freezing temperatures around the county, but we'll see a nice rebound in temperatures this afternoon. A surface high to our east will allow for southerly winds today, and in the upper levels, ahead of a digging trough in the Four Corners region, a shortwave ridge will build over the Southeast. Temperatures aloft will be slightly warmer this afternoon than yesterday, but this should still allow highs to jump into the 60s today. The only fly in the ointment preventing maximum heating will be an increase in cirrus clouds as the afternoon progresses. I still expect the high to top out around 61 this afternoon. By this evening and overnight, cloud cover should continue to increase and thicken as a series of subtle upper level disturbances approach the region. Combined with warm air advection, this should allow for the development of some showers across the Arklamiss overnight. However, I expect any rain to remain to our west through sunrise. Expect the overnight low to be much warmer at around 44.

Sunny, Warming Trend Begins

2009-12-21T08:19:00.003-06:00

A very strong storm system moving through the Gulf of Mexico brought heavy rains to the state on Friday, followed by much colder weather on Saturday. It was still cool yesterday, but at least the sun made a return appearance. The sun should continue in full force today as our surface weather pattern is dominated by a high pressure in the Florida Panhandle. Aloft, generally flat westerly flow will be the rule as a strong storm system begins to dig into the western states. As the flow has turned more westerly aloft, a weak warm air advection regime has begun, which will allow highs to top out around 56 this afternoon. With clear skies and calm winds in place tonight, we should see another chilly evening. Lows tomorrow morning will be near 31.

The big news in the weather world will be the big pre-Christmas storm that will affect much of the eastern half of the nation. With the primary surface low moving across Missouri, severe weather will be more of a threat than winter weather. However, like the overwhelming majority of cool season events, the threat for severe weather is contingent upon needed buoyancy for our area. Model guidance is in excellent agreement that this will be a very dynamic storm system with very favorable wind shear profiles. On the other hand, a very narrow ribbon of weak buoyancy (MLCAPE <500 J/kg) is forecast to be present into southwest Alabama. Regardless of the severity of the convection, late Wednesday through Thursday figures to be a wet period across the state. After the passage of the storm system, much colder air will filter into the state, and indeed, Christmas Day and Saturday will feature highs in the 40s.

Cloudy & Cool

2009-12-18T08:12:00.004-06:00

Most places in the county received a good soaking overnight with rainfall totals between 0.50-1.00". Light rain continues to fall in the Starkville area, which is being aided by mid-level convergence. The rain should end from west to east by 10 a.m. Otherwise, skies will remain cloudy for the remainder of the morning and early afternoon in the wake of a storm system in the northern Gulf of Mexico. By this afternoon, there is an outside chance that we might see a peak or two of sun, but skies will still remain mostly cloudy. Highs this afternoon will top out around 50. An upper level storm system will approach the area late overnight, but it should only reinforce the cloud cover. Moisture will be very anemic as this system passes through, so it doesn't seem likely that any precipitation will occur. Temperatures tomorrow morning will be near 35.

We'll get a chance to dry out this weekend, but clouds will likely stick around for much of Saturday in association with the upper level disturbance. This disturbance will also usher in a fresh supply of Canadian air. In fact, highs on Saturday will likely be in the low to mid 40s. It feel much colder than that as northwest winds could gust as high as 25 mph. On Sunday, we should finally see a good supply of sunshine, but temperatures will remain on the chilly side with highs in the in the mid 40s. Our next chance of rain appears to be the middle of next week as a big pre-Christmas storm system will affect much of the eastern half of the country. Early speculation was that this system may produce some winter weather, but at this time, severe weather is more of a concern to me. If any winter weather were to occur with the storm system, it would occur on the backside and would be light in nature.

Today marks the last blog post of work day weather forecasts for MSU, Starkville, and Oktibbeha County. Although I will continue to be a MSU employee through the spring semester, I have moved to Tuscaloosa in order to focus on pursuing a dream career with the National Weather Service. I am truly indebted to the Department of Geosciences at MSU because it was responsible for educating and employing me for the last 9 1/2 years. I may be biased, but I feel like our department as a whole has the best teachers on campus. Anyone interested in broadcast or operational meteorology should give MSU some serious consideration. Our Broadcast Meteorology Program IS the best in the country, and our Operational Meteorology Program has improved by leaps and bounds in the last 5 years. It's no coincidence that, in that time frame, several MSU graduates have obtained employment in the NWS and many more seem poised to land there in the future. Needless to say, I fully recommend MSU for any interested in meteorology!

Continued Cool

2009-12-16T06:47:00.003-06:00

Last night was a classic example of the difficulties with forecasting when an active subtropical jet is in place. Despite a cold front moving through the area yesterday, a newly developing storm system in the Gulf of Mexico produced a considerable amount of high clouds. As a result, temperatures are just above freezing to start the morning. Satellite imagery suggests the high clouds will persist for much of the day, but some filtered sunshine will occur at times. At the surface, high pressure in Indiana and low pressure in the western Gulf of Mexico will combine to produce a cool northeasterly breeze. Highs this afternoon will top out around 47. High clouds will remain in place tonight and will probably only thicken towards sunrise. Lows tomorrow morning should be near 32.

Cloudy, Breezy, & Much Cooler

2009-12-15T07:34:00.003-06:00

A large complex of showers and thunderstorms across southern Mississippi yesterday blocked the inflow to the north ahead of the cold front, and as a result, most communities around the county remained dry. Another band of moderate to heavy rain is located across central and southern Mississippi in association with a cold front. Behind the front, temperatures have dropped into the lower 50s this morning across the area. Skies will be mostly cloudy today, and with strong cold air advection occurring in the wake of the cold front, current temperatures will probably be the warmest we see today. Temperatures will drop into the upper 40s late this morning before slowly dropping into the mid 40s by late this afternoon. It will be rather breezy today with wind gusts exceeding 20 mph at times. By this evening, skies should become mostly clear, but the boundary layer will likely not decouple overnight. As a result, temperatures should not plummet, but it will still be a chilly night. Lows tomorrow morning will be near 31.

Foggy Through Noon, P.M. Showers

2009-12-14T06:40:00.004-06:00

The weekend was a bit dreary, but we managed to escape the heavier rain that fell across the southern part of the state. Temperatures warmed slightly yesterday and that trend will continue today. A weakening polar vortex can be attributed to the warming as it has allowed the jet stream to lift to our north. As a result, an area of low pressure located across western Kansas will move northeastward today and should be located near Detroit this evening. Trailing the area of low pressure will be a cold front that will stretch through northeast Texas. At the same time, isentropic ascent will commence across the region. These two factors argue for decent lift across the area, and this should result in a chance for rain, particularly tonight. However, a stalled frontal boundary along the Gulf Coast will provide another source for lift, and this should concentrate the heaviest rains in its vicinity across southern Mississippi.

In the meantime, expect the fog and mist to persist for much of the morning hours. By this afternoon, the fog should slowly dissipate, but low clouds will remain in place as a considerable amount of moisture will be trapped below an inversion. Highs should manage to top out around 63 this afternoon. Rain chances will increase after 6 p.m. as the aforementioned cold front approaches northwest Mississippi. The most rain should fall before midnight, but a few showers will remain possible through 3 a.m. The front should pass through the area just after midnight, which should quickly drop temperatures into the 50s. The low tomorrow morning will be near 48.

Mostly Cloudy, Chilly; Slight Chance of Sleet Before Sunrise

2009-12-11T06:40:00.004-06:00

Temperatures have fluctuated between the upper 20s and 30 for much of the night as an extensive cirrus shield blanketed the area. These clouds will stick around for much of the day as a tropically connected branch of the subtropical jet remains entrenched across the region. The confluence of the subtropical jet and the polar jet will take place to our north, which will place the Deep South in the right entrance region of the jets. The vertical motion associated with this quadrant will help initiate a surface low pressure in the western Gulf of Mexico this afternoon. The low should contribute to a gradual increase in moisture over the course of the day. However, rain chances will be kept at bay as a strong surface high remains in control of our weather. Since skies will be mostly cloudy today, highs will remain on the chilly side as we should only top out near 43.

By this evening, cloud cover will thicken and lower as moisture increases due to the surface low in the Gulf and as isentropic processes commence. I'm always leery of model guidance that holds off the onset of the precipitation when moderate large scale ascent is occurring. If the models are indeed correct, we should remain dry through sunrise tomorrow morning. However, with the strong vertical lift, I feel that a slight chance of precipitation is warranted just before sunrise. If precipitation does indeed occur before sunrise, the amount of dry air in the lowest 8,000 feet would support evaporative cooling. The evaporative cooling would produce a thermal profile supportive of a period of sleet. I don't expect any travel problems to occur as the precipitation will be very light. Lows tomorrow morning will be near 33.

Mostly Sunny, Cold

2009-12-10T06:37:00.004-06:00

It's a very cold start to the morning as temperatures are sitting in the upper 20s. That indicates how impressive this modified arctic air mass is, especially given the fact that winds were never close to being calm and most of the area received 2-4" of rain in the last couple of days. The weather maps show that the upper air pattern over the region is dominated mostly by quasi-zonal flow, with a slight hint of west southwesterly flow. A very strong branch of the subtropical jet stream has merged with the polar jet across the Ohio Valley. A stream of high cirrus clouds is evident on infrared imagery extending from the Pacific through Texas and along the Gulf Coastal states. It's possible that a few of these clouds may pass through the area at times today. Otherwise, skies should be mostly sunny as high pressure builds into the region. With the modified arctic air mass in place, I think temperatures will struggle to reach the lower 40s today. In fact, I think highs will only top out near 41 this afternoon. It will not be as breezy today as it was yesterday, but winds could gust as high as 15 mph, particularly this morning. The forecast for tonight is somewhat tricky as cirrus clouds associated with the STJ will begin to stream into the area. This should put a cap on the radiational cooling to a degree, but it's still hard to underestimate the strength of this air mass. I'll go with a compromise and forecast a low of 27 tomorrow morning.

Snow in the Picture?

2009-12-03T15:01:00.002-06:00

An interesting weather scenario will unfold late Friday night and Saturday morning. Upper level energy ejecting out of Texas tomorrow evening will result in the development of a surface low in the western Gulf of Mexico. As this low strengthens and moves eastward Friday night and Saturday morning, it will spread moisture northward across the Deep South. Meanwhile, as a deep upper air trough moves over the region, it will supply a reinforcing shot of cold, Canadian air. The combination of the upper level dynamics and the surface low will generate enough lift for a band of light to moderate precipitation to develop across Louisiana, southern Mississippi, and southern Alabama. Lighter amounts of precipitation will fall across central Mississippi and Alabama.

The coupling of the cold air and moisture will be enough to cause some winter weather concerns, especially Saturday morning. Although some light snow will likely occur between midnight and 8 a.m. on Saturday, I don't feel like there will be any travel concerns for Oktibbeha County. This is primarily due to the deeper moisture remaining to our south and very warm soil temperatures. In fact, soil temperatures on the North Farm at MSU are 51 F. It would take a heavy burst of snow to cause much in the way of accumulations, and the lift needed to generate a heavy burst will remain well to our south. If you're headed to southeast Louisiana, southern Mississippi, or southern Alabama, there could be some accumulations (up to 2") of snow.

Drizzle/Light Rain Possible, Remaining Cool

2009-12-02T08:29:00.004-06:00

An area of low pressure is currently located near Greenwood, MS, with a cold front stretching to the southeast of the surface low. This storm system will gradually move to the east throughout the day, and it looks like the front will push through our area around noon. The heaviest rain and thunderstorms are ongoing across Alabama and Florida, but a band of light to moderate showers that is associated with the upper level energy is occurring across Arkansas and western Mississippi. As the upper level energy pivots eastward, a few patches of light rain and drizzle will be possible through 4 p.m. Clouds will hang tough today, and highs will only manage to top out near 52. Winds will become breezy late this afternoon and this evening as the storm to our east deepens. Wind gusts could possibly exceed 25 mph at times. In the wake of the surface and upper level storm system, low level moisture will remain trapped below a strong inversion. As a result, skies will remain cloudy overnight, which will keep lows near 40 tomorrow morning.

Morning Showers, Turning Much Colder

2009-11-30T07:12:00.002-06:00

It's been a wet morning thus far, and additional showers will be possible through 10 a.m. The band of rain is associated with an eastward moving cold front that is currently just to our northwest. It appears that clouds will be tough to break for much of the day. With weak cold air advection behind the front and clouds hanging tough, highs today will be rather chilly. In fact, the temperature this morning will actually be warmer than it will be this afternoon. Look for temperatures to drop to near 50 late this morning, and then briefly spike rise to 52 late this afternoon. Northwest winds gusting over 20 mph at times will make temperatures feel even colder today. By this evening, skies should become mostly clear and winds will begin to subside due to decoupling and a lessening pressure gradient. As a result, lows tomorrow morning will be near 36. An active weather pattern will setup this week thanks to a subtropical jet stream. Tomorrow should be dry, but rain will return early Wednesday morning as an area of low pressure moves out of the Gulf of Mexico. In the wake of the midweek system, much colder air will grip the region Thursday, Friday, and Saturday. In fact, highs one of those days may not break 45!

Sunshine Returns, Warmer

2009-11-19T07:24:00.004-06:00

Clouds broke up a lot earlier than I expected overnight, and I'm surprised the low only got to 36. We should enjoy a sunny day today as the cut off low continues to drift northeastward into the Great Lakes states and an area of high pressure dominates the region. This also means temperatures will be much warmer than the last couple of days but still on the cool side. Highs should be able to top out near 62. Light winds and clear skies should provide a good radiational cooling setup overnight. Lows tomorrow morning will be near 37.

Cloudy, Chilly

2009-11-18T06:42:00.004-06:00

Amazingly, temperatures this morning are slightly cooler than temperatures yesterday afternoon. That's due in part to a persistent stratus deck that hung tough overnight. Forecasting when the stratus deck breaks up will be key to the forecast this today. Unfortunately, the cut off low responsible for the low clouds continues to spin across Missouri, and it will only drift slightly northward today. As a result, clouds should hang tough again today and keep temperatures on the chilly side again. Highs will top out around 53 this afternoon. The low clouds should begin to break up after midnight as some slightly drier air works its way into the area. I don't think skies will be completely clear or else we could be looking at a potential freeze. However, with a few lingering clouds overnight, lows should be able to drop near 37 tomorrow morning. Beginning early next week, an El Nino like pattern will set up, so a return to wet weather appears likely for the last week of November.

A.M. Sun, Cloudy/Cold/Drizzly This Afternoon

2009-11-17T06:43:00.004-06:00

The cold front that brought rain yesterday evening has pushed well to our east. Strong cold air advection in the wake of the frontal passage will dominate the weather today. Although skies are temporarily clear, low clouds associated with the cut off low will return late this morning and this afternoon. A little sunshine this morning may allow temperatures to top out around 52 as opposed to holding in the 40s if a low cloud deck were present all day. However, it will feel raw by this afternoon with chilly temperatures, breezy winds, and even some patchy drizzle. I feel strongly low that low clouds will hang tough overnight, and this will prevent any chance of freezing temperatures. Still, it's going to feel quite cold with a few patches of drizzle early in the evening. Temperatures should be near 37 tomorrow morning.

Late Afternoon/Evening Showers, Warm

2009-11-16T06:36:00.003-06:00

The dry streak ends today as a storm system approaches from the west. A line of showers and thunderstorms currently stretches from southeast Texas to southeast Missouri in advance of a cold front. Surface ridging in the Gulf of Mexico has prevented a strong return flow into this system, and this is resulting in minimal cloud cover in advance of the front. As a result, we should see mostly sunny skies this morning, but clouds will thicken more as we head throughout the afternoon hours. This should allow temperatures to top out around 72 this afternoon. The front will steadily push eastward today and should be located across western Mississippi by late this afternoon. At the same time, the upper level energy will become cut off from the jet stream. This combined with meager moisture ahead of the front will actually result in the line of showers weakening substantially over the course of the day. However, we will likely see the line push through our area after 4 p.m. and should exit to the east by 7 p.m. Rainfall amounts will be light with most communities seeing less than 0.25". The front will pass through our area after 8 p.m. with temperatures quickly dropping into the 50s by 10 p.m. Clouds will hang tough overnight, but strong cold air advection will allow temperatures to drop near 42 tomorrow morning.

A Few High Clouds, Mild

2009-11-13T06:36:00.003-06:00

It's a chilly start to the day with temperatures currently running in the upper 30s. The pesky cut off low that plagued our weather for the past couple of days will exert very little influence on our weather today. In fact, a shortwave ridge will build across the area throughout the day as another trough digs into the Four Corners. This should keep us dry, but a few cirrus clouds will pass overhead at times today. This will prevent temperatures from reaching their maximum potential, but highs should still top out around 69 this afternoon. Winds will veer around to the southeast tonight, which should increase dew points. I have a hard time believing skies are clear overnight with the amount of cirrus clouds to our west, but lows should be able to drop near 44 tomorrow morning.

The weekend weather looks great, especially Saturday with mostly sunny skies and highs in the low to mid 70s. The game on Saturday night should be played under a few clouds with temperatures falling into the 50s throughout the course of the game. A few more clouds will be likely on Sunday with highs in the mid 70s. Our dry streak will come to an end late Tuesday or Wednesday as a cut off low swings a cold front toward the region.

Sunny, Pleasant

2009-11-12T06:30:00.003-06:00

A few clouds moved through the area this morning and kept temperatures in the low to mid 40s. We remain under the influence of northwest flow aloft due to the cut-off low to our east. The models overestimated the strength of the cold air advection yesterday, which lead to highs topping out a little warmer than I expected. Once again, I think models may be a tad too cool today as a warm air advection regime will commence. Nonetheless, a cooler surface air mass did filter into the area overnight, and this should keep highs slightly cooler than yesterday. With sunny skies highs should top out near 67 this afternoon. A good radiational cooling setup will support some chilly temperatures tonight. However, I don't like going to aggressive with temperatures when warm air advection is occurring. Still, lows should be able to drop to near 39 tomorrow morning.

Sunny and Breezy

2009-11-11T06:39:00.002-06:00

We took a glancing blow from Tropical Storm Ida yesterday as most locations received less than 0.5" of rain. That's a welcome relief as we've been deluged with over two feet of rain in the last couple of months. The other good news is that we're in store for another relatively dry weather pattern for the next several days. Aloft, we'll be under the influence of an upper level trough (the remnants of Ida) to our east, which will produce weak cold air advection aloft. At the surface, an area of high pressure to our west and north will produce northwesterly flow throughout the day. The combination of these two will result in sunny skies, gusty winds, and highs around 67. Winds could gust as high as 25 mph again today as a result of a strong pressure gradient. Skies will be clear this evening, but winds will stay up through the night. Therefore, lows tomorrow morning will be near 43.

Light Rain This Morning, Dry This Afternoon

2009-11-10T06:21:00.004-06:00

Tropical Storm Ida made landfall just a short time ago near Dauphin Island, AL. A classic indication of a tropical system phasing with a mid-latitude system can been seen by analyzing the current radar image. These type of systems often have a well defined back edge to the precipitation shield, and this case is no exception. Starkville and Oktibbeha County will receive only a little in the way of rain from this system, but Columbus and especially places to the east have received and will receive heavy rain today.

Some off and on light rain and drizzle will likely continue for much of this morning, but we should dry out this afternoon as Ida begins to move eastward across the Florida Panhandle. Clouds should hang tough all day, and this will only allow temperatures to top out near 63. It will also be breezing with winds exceeding 20 mph at times throughout the day. I think we may clear after 9 p.m., but a few low clouds will develop early tomorrow morning. Lows should be able to drop near 49 tomorrow morning.

Rain Returns Overnight

2009-11-09T06:41:00.003-06:00

The weather maps show a complex situation this morning with a weak upper level trough approaching the area and Hurricane Ida in the northern Gulf of Mexico. Over the course of the day, these two systems will start to become intertwined. One fly in the ointment is that no model is picking up on the showers around the Jackson area that are associated with the upper level disturbance. I think it's possible this disturbance could generate a few light showers across our area this afternoon. Regardless of whether it rains, skies will be mostly cloudy throughout the day due to cirrus blow off from Ida, and highs should be able to top out near 68 this afternoon. An area of high pressure near the eastern shore of Virginia and Hurricane Ida will produce a strong pressure gradient, which will result in breezy conditions today. Some wind gusts could approach 15 mph this afternoon.

The forecast overnight is the tricky part. Ida should be approaching the Alabama/Florida coasts by sunrise tomorrow morning. On this path, the heaviest of rains will be remain to our south and east, but some rain from Ida will still work its way into the area after midnight. Winds will be even more breezy overnight than during the day with gusts up to 20 mph. Lows tomorrow morning will be near 56.

If Ida takes the track I expect or goes slightly further east, we'll get lucky with this system with only minimal rain amounts. However, if Ida shifts its track slightly westward, we'll be dealing with some heavy rain. If any changes occur, I'll update the forecast as needed.

Dry, Pleasant Weather Continues

2009-11-06T06:39:00.003-06:00

Clear skies, calm winds, and dry air made for an excellent radiational cooling setup, and temperatures this morning are running in the mid to upper 30s. As the day progresses, a flat upper ridge will build across the region, which will result in continued dry and mild conditions. Skies will be sunny again today with highs topping out near 71. A surface high will slide off to our east by tonight, and winds will begin to veer to the southeast. This will increase dew points enough to keep lows in the 40s overnight. Still, another good radiational cooling setup will allow temperatures to drop near 42 tomorrow morning. The weekend looks great with a good supply of sunshine both days, although, there may be a few more clouds present on Sunday. Highs each day will be in the mid 70s. Our next chance of rain looks to arrive on Monday.

Sunny and Mild

2009-11-04T06:38:00.002-06:00

The front that I was expecting to give us a reinforcing shot of drier air washed out before moving through our area. As a result, temperatures are running the mid 40s to start the day. Another great fall day is on tap with a good supply of sunshine and slightly warmer afternoon temperatures. Highs should be able to top out near 74 this afternoon. A slightly strong upper air disturbance will push a cold front through the area overnight. This front won't have much of an impact on sensible weather, and the atmosphere appears to be too dry for clouds to develop. Clear skies and light winds should allow temperatures to drop near 44 tomorrow morning.

Great Fall Day

2009-11-03T06:36:00.004-06:00

Not a lot to mention on the weather maps this morning, but the primary item of interest is a cold front that is located north of Memphis. This front will push southward over the course of the day and should sweep through the area early this afternoon. There is even less moisture than expected with the front, so we should be in store for another sunny day. The front will bring in a drier supply of air and slightly cooler temperatures with highs topping out near 68. Winds will be breezy after the frontal passage this afternoon with some gusts exceeding 15 mph. Winds will subside tonight, and with clear skies and drier air in place, lows tomorrow morning should be able to dip down to 41.