Fall Like Weather

A stalled frontal boundary provided a good soaking rain for most areas over the weekend. The front has finally pushed to our south as a much cooler and drier air mass has taken control. Despite a few pesky clouds, temperatures are generally running in the lower 60s this morning. With some cooler air above the surface, we'll likely see a few patchy afternoon cumulus this afternoon. Highs will be pleasant this afternoon as we top out near 82. It should also be mentioned that winds may gust as high as 15 mph this afternoon as vertical mixing takes place. By this evening, dry air and clear skies will be in place, but winds won't completely go calm. This, combined with most areas receiving over an inch of rain in the last 24 hours, will likely keep lows around 58 tomorrow morning.

El Nino Update and Long Range Forecast

A weak El Nino episode continues across the equatorial Pacific Ocean with anomalously warm pockets in the central and eastern Pacific. Although most of the anomalies are generally ~1 C above normal, a small anomaly in excess of 2 C is present near 105 W. With the warmer than normal water continuing across the equatorial Pacific, all Nino regions remain above 0.5 C. With an increase in the trade winds in July, we saw the very warm subsurface water cool and shrink. In fact, a cool anomaly is now present between 50 and 100 meters below the surface near 110 W. However, warmer than normal water is present 150 meters below the surface between the 160 W and the Dateline.

In recent weeks, trade winds have lessened and allowed for warming across the equatorial Pacific. Running 5-day averages show weaker than normal trade winds existed across the entire equatorial Pacific. As a result, a large area of greater than 1 C anomalies was present between 135 W and 165 E. The 29 C isotherm is located the farthest east (170 W) it's been in almost six weeks. Furthermore, the 30-day average of the SOI has finally fallen back to around -5. All of this evidence supports a weak El Nino signature, and the large majority of computer models suggest this will strengthen as we head into fall. This episode should peak by the end of the year, followed by a slow decrease in strength as we head into 2010.



Needless to say, this El Nino event has not had the ocean and atmospheric support that many El Nino events have had. Whether the ocean has led the atmosphere or vice versa, the ocean and atmosphere have rarely been working in tandem at the same time for the last few months. Global relative AAM remains near climatology after being negative for the last week. Mountain torque has spiked to near 2 standard deviations above normal, with positive contributions from the Americas and tropics. Frictional torque is near climatology after peaking at around 1 standard deviation above normal in the last week. The tendency of relative AAM remains positive and is contributing to a weak GWO phase space projection in Octant 4. The current upper air pattern generally supports this phase based on 250 mb composites centered on August 26.




An incoherent MJO signal has been observed for the last several weeks, and this appears likely to continue for the next couple of weeks. Notwithstanding, pulses of enhanced uplift will likely continue across the Arabian Sea, Bay of Bengal, eastern Pacific, and the Atlantic basin for the next 10-14 days. This will pose a heightened risk for tropical cyclone activity in the Atlantic and eastern Pacific. After this time period, forecasts show that the Atlantic basin, in particular, may see a lull in tropical activity. Near the Dateline, OLR anomalies have been higher than normal for most of August, but recent indications are that negative anomalies may be returning. If this continues over the next week, it would suppress convection across the Arabian Sea and Bay of Bengal.

With the GWO in octants 8 and 1 a couple of weeks ago, these effects will begin to be felt in the long range forecasts. The north Pacific jet will extend this week and will result in the formation of a trough in the Pacific Northwest during the latter half of this week. For our area, we'll begin the week under the influence of an unseasonably strong trough. This will result in below normal temperatures and precipitation for much of week 1. By the end of week 1, a flat ridge will become more established over our region and result in near normal to slightly below normal temperatures and precipitation. Given the weak GWO projection, I'm slightly less confident about week 2, but we should be dominated by a flat ridge aloft for the first half of week 2. This will result in near to slightly below normal temperatures and precipitation. The flat ridge may once again dominate this period, but the influence of a trough to the west will likely create better chances of rain with slightly below normal temperatures near the end of week 2. Overall, I don't see any signs of oppressive heat in the next couple of weeks.

Warm, Small Chance of Rain

With a few areas receiving rain yesterday, fog has formed this morning as temperatures are running in the upper 60s. For those areas that didn't receive rain yesterday, chances are great you won't see any today since we'll be sandwiched between weather systems. The upper low that has plagued us for the last few days will slowly drift off to the east, and it will be replaced by a cold front that will approach the state this evening. In between, there will be some clouds and a few isolated afternoon showers and thunderstorms. However, the chance of getting wet today is pretty small. With less in the way of precipitation, highs should top out near 90 today. Cloud cover will thicken overnight as the cold front approaches. Lows tomorrow morning will be near 68.

The cold front will pass through the area late Saturday evening, but a few showers will likely develop ahead of the front tomorrow afternoon and evening. Highs should top out in the mid 80s tomorrow afternoon. Despite the front passing through Saturday evening, it will likely take until late Sunday morning for the clouds to clear. That should keep highs on Sunday around 80, but there is a chance we might stay in the 70s all day. This Canadian air mass will be really evident on Monday morning with lows in the mid to upper 50s!

Isolated PM Storms, Warm

An analysis of area soundings and infrared satellite loops confirms low-level moisture has increased substantially in the last 24 hours as winds have veered around to the southeast. Satellite images show much more cloud cover this morning than I anticipated and has kept temperatures in the mid to upper 60s. The pesky upper-level low to our south will slowly move eastward today in response to another disturbance pushing southward through the Midwest. The upper low will finally have enough moisture to work with to produce slightly greater coverage of showers and thunderstorms this afternoon. However, these showers will still be isolated, and the best chance for rain will be to our south and east. Despite a few afternoon cumulus clouds, highs should top out near 89 today. It's tough to completely rule out an isolated shower overnight with an upper air disturbance moving through the area, but consider yourself lucky if you get wet. With cloud cover sticking around tonight, low temperatures in the morning will be near 69.

Returning to Normal

Some fog and low stratus clouds have developed this morning as temperatures are running in the mid 60s. The pesky upper level low centered to our south can be blamed for a few of the stratus clouds this morning, and it will allow for more afternoon cumulus to develop later. Although the atmosphere is slowly beginning to moisten up, it's hardly worth mentioning a chance of rain today as only one or two rogue showers may develop this afternoon across the area. Temperatures will return to near normal with highs topping out near 90 this afternoon. Other than a patchy cloud or two tonight, skies will be clear. Winds will begin to veer around to the southeast overnight and moisture will slowly be on the increase. Look for temperatures tomorrow morning to be near 67. I'm growing more confident that temperatures next week will be even cooler than we experienced this past weekend.

Partly Cloudy, Slightly Warmer

We can say goodbye to the trough that influenced our weather for the last few days and welcome the ridge that will replace it for a for more days. This will allow our "cool" air mass to modify and warm up beginning today. The only fly in the ointment is a small upper level low located within this ridge, which will allow for a more widespread coverage of afternoon cumulus today and should keep temperatures somewhat in check. We'll continue below normal in the temperature department for one more day as highs will top out near 86 this afternoon. Other than a few patchy clouds, skies should remain mostly clear this evening with temperatures dropping to near 65 tomorrow morning. If this fall like air mass spoiled you, you'll like the feel of the temperatures late this weekend and the start of next week!

Afternoon Clouds, Pleasant

The weather for the last couple of days is some of the nicest weather you can ever hope for in August. In fact, highs yesterday didn't even break 80 degrees! Morning temperatures have been perfect to open those windows and let in some fresh air. We're starting the work week on the cool side with temperatures in the upper 50s. Our air mass will begin to modify today as an upper trough weakens and begins to lift slightly to the northeast. Highs will top out near 84 with cumulus clouds dotting the sky again this afternoon. An upper level disturbance will edge its way into the area overnight and may be able to generate a few clouds. This should keep temperatures warmer tomorrow morning with lows near 62.

Final Round of Rain, Turning Drier Late

Much needed rain fell yesterday, and we stand a good chance at picking up additional rain today as a cold front remains located to our north near the I-40 corridor. The front outraced its main upper air support, which has caused the front to slow to a halt. As a result, the front will remain to our north for much of the day and will result in another round of showers and thunderstorms beginning later this morning and lasting into the afternoon. Skies will be cloudy for much of the morning, but a few breaks in the clouds after lunch will result in mostly cloudy skies. Temperatures should top out near 84 this afternoon. The upper air trough to our north will deepen by tonight, and this will finally push the cold front through the area after midnight. Drier and cooler air will filter in behind the front, and in fact, temperatures tomorrow morning will be near 65.

The weekend weather looks wonderful and will provide a sneak preview of fall during the mornings. There will likely be a few afternoon cumulus clouds tomorrow and Sunday. Highs will be in the low to mid 80s tomorrow and mid 80s on Sunday, and lows will be near 60 Saturday morning and in the upper 50s Monday morning.

Two Rounds of Rain

Rain chances will increase considerably today as an upper air trough to our north pushes a cold front toward the region over the next 24 hours. The main precipitation associated with the front currently extends along and north of the I-40 corridor, but this precipitation shield will slowly advance to the southeast throughout the day. Before we deal with that precipitation, scattered showers and thunderstorms should develop this afternoon. All in all, it would be a pretty good idea to take an umbrella with you to work or class. We should get a good supply of sunshine this morning, which will warm temperatures up quickly. Cloud cover will quickly increase this afternoon, but highs should be able to top out near 88. The cold front will be knocking on the state's door overnight, and this should allow for a better chance of showers and possibly a thunderstorm, especially after midnight. Lows should be near 72 tomorrow morning. After the front passes through tomorrow, it looks like a beautiful late summer weekend with highs in the 80s and lows possibly dropping into the 50s!

Mostly Cloudy, Scattered PM Showers

It's another muggy start to the morning with temperatures in the low to mid 70s under cloudy skies. We may see a few breaks in the clouds this morning, but the large majority of the day will likely be cloudy. Model guidance differs considerably in the amount of forcing present today to generate showers and thunderstorms, but they almost all agree that we will get wet today. That's hard to argue against looking at Jackson's sounding from last night with precipitable water over 2". I think we'll see scattered showers and thunderstorms develop this afternoon, but I don't expect a washout by any means. Before the showers develop, I think highs will top out near 88. We'll be dry tonight, but cloudy skies should only allow temperatures to drop near 73 tomorrow morning. As a trough builds over the eastern half of the country at the end of the week, it should push a cold front through the area late Friday night. This will make for a very pleasant weekend with below normal highs and lows!

Tropical Satellite Perspective

Before retiring for the evening, I just wanted to leave you with some excellent tropical links from a satellite perspective. These come from CIMSS (http://cimss.ssec.wisc.edu/tropic2/):

Satellite imagery devoted to Bill:
http://cimss.ssec.wisc.edu/tropic2/real-time/storm.php?&basin=atlantic&sname=03L&zoom=4&img=1&vars=1111100000000000000000&loop=0

Animated microwave loop of Hurricane Bill between 12 a.m. this morning until 6:45 p.m. this evening:
http://cimss.ssec.wisc.edu/tropic/real-time/marti/2009_03L/webManager/displayGifsBy12hr_04.html
-Notice the eye wall contractions and expansions.
-The "hot towers" surrounding the eye indicate a deepening of the system.
-Notice how much stronger Bill gets when it crosses 50 deg W; that latitude was where the oceanic heat content spiked and Bill certainly took advantage of that this evening.

This link comes from NASA was taken by Aqua this afternoon (choose from 2 km, 500m, or 250 m resolution):
http://rapidfire.sci.gsfc.nasa.gov/gallery/?2009230-0818/Bill.A2009230.1640.1km.jpg

My thoughts remain unchanged regarding the future track of Bill. I still don't think Massachusetts or Maine should write this off, but I think the Canadian Maritimes will take the brunt of Bill. However, the Canadian ensemble shifted west this morning, and the afternoon GFS ensemble has also shifted west.

Cloudy, Light Showers

The current upper air pattern would normally dictate that we would have a hot and dry pattern right now. However, the remnants of Claudette will prevent either from occurring today. Similar to yesterday, we'll have a chance of scattered light showers this afternoon so be sure to pack your umbrella before heading to work or class. Widespread cloud cover will also help to keep temperatures well below normal again today as highs will top out near 83. The threat of showers should end tonight, but extensive cloud cover will hang tough and should keep lows near 74.

Thoughts on Bill

As fast as the tropics exploded, they have pretty much settled down as quickly -- with one notable exception. Tropical Storm Claudette made landfall late last night as a weak tropical storm and is currently located just near the Golden Triangle area in Mississippi. Ana has once again been downgraded to a remnant low pressure center as it is just south of Hispaniola. It's too early to give up on Ana just yet as it should emerge into the eastern Gulf of Mexico later in the week. As we saw with Claudette, the environment in the Gulf is certainly supportive of quick intensification, so residents along the northern Gulf Coast should still keep an eye on the storm formerly known as Ana.


The big tropical news continues to be Hurricane Bill which is located about 950 miles east of the Lesser Antilles. The satellite presentation has begun to look extremely impressive this afternoon with solid banding, a symmetrical appearance, well-established outflow, and the development of what appears to be an eye. 85 GHz microwave imagery also suggests deep convection is beginning to surround the center of the hurricane. The good news is that Bill shouldn't threaten any land masses within the next several days, and that's a good thing because it will likely become a major hurricane tomorrow. The dynamic environment remains very favorable for some additional intensification, and the thermodynamic will become very favorable once Bill moves west of 50 degrees West early tomorrow morning. If it's not a major hurricane by that point, expect it to quickly attain that status and likely Category 4 strength within the next few days given the expected light shear, moist ambient air, and favorable thermodynamic environment.

The largest question remains the future track of Bill. Bill has been steered for the last few days by a deep layer subtropical ridge. A weakness in the ridge centered near 30 deg N and 47 deg W should allow Bill to turn slightly more north of west over the next couple of days. By Wednesday, the subtropical ridge re-strengthens but will quickly be pushed eastward by a trough digging into the Midwest on Thursday. As it does so, Bill should begin to move more northwest and then north by Saturday as it will be sandwiched between the trough to its west and ridge to its east. Where exactly this north turn begins will be critical as to whether the United States gets hit or whether the Canadian Maritimes gets hit.

Dynamical model guidance has shifted westward today, and it will be interesting to see if this is indeed a trend. I still prefer the consistent Canadian model, which does bring Bill very close to Maine by Sunday. I'm leaning slightly east of it's track, but based on the current model track, the New England coastal areas could experience tropical storm force conditions late this weekend. I don't want to completely write off the threat that the U.S. gets hit, but I think New England would be the most likely area to experience landfall.

Increasing Clouds, Scattered PM Showers

It's somewhat of a tough forecast today as Tropical Depression Claudette spins to our south. The heaviest rain associated with Claudette should also stay to our south today. However, a few scattered showers and thunderstorms can't be ruled out this afternoon and evening. Cloud cover will increase considerably by this afternoon, and the combination of clouds and showers will hold temperatures below normal this afternoon. In fact, highs this afternoon will top out near 85. As Claudette approaches western Alabama by late this afternoon, the pressure gradient will tighten and allow for winds to gust as high as 20 mph. The remnants of Claudette will be located very close to our area just after midnight, but the heaviest rain should remain to our south. However, a few isolated showers will still be possible overnight. Lows tomorrow morning will be near 72.

Quick Tropical Update

-A concentrated area of showers and thunderstorms has developed a mid-level circulation in the eastern Gulf of Mexico this evening. Mid-level circulations typically take a day or two before they can translate down to the surface, and it will be a race to the coast as to whether or not this develops. I wouldn't be surprised if this does develop into a depression or tropical storm before moving onshore, but regardless, it will bring heavy rains and gusty winds to the northern Gulf Coast.
-Tropical Storm Bill continues to churn in the eastern Atlantic. The current satellite presentation looks pretty healthy as shear has relaxed some from earlier today. Bill will be poised to strengthen modestly once west of 50 deg W, and I wouldn't be surprised to see this become a major hurricane within the next 5 days. Model guidance has generally shifted to the right today with the exception being the UKMET. I hate to change my forecast so quickly, but I'm now leaning slightly more to the right and think Bill could be a re-curving storm. I still think the East Coast needs to watch Bill, especially from Wilmington to Maine as powerful hurricanes have a way of altering their environment. If Bill can become a Category 4 or 5 hurricane, it will be interesting to see what effect it has on the upper level ridge late next week.
-Ana continues to look unimpressive, but if it can fight the dry air to its west, some strengthening may be possible. Model guidance takes Ana through the Caribbean and over Hispaniola. If this occurs, a weak storm like Ana may not be significantly affected by the rugged terrain and may be able to strengthen quickly once over the very warm waters of the Florida Straits. It does look like Ana may wind up in the Gulf of Mexico, but south Florida and the Keys should keep an eye on Ana over the next few days.

Tropical Notes

-T.D. 2 was likely a minimal tropical storm for a very brief period of time Wednesday morning as objective Dvorak numbers were T2.5 when deep convection surrounded its center. Since then, the depression has weakened to a tropical wave as strong wind shear and dry air put a beating on the system. However, the remnant of the depression has looked much more organized today, but strong wind shear and dry air will continue to be the main impediments to short-term development. Regardless of whether it regenerates, model guidance does indicate this wave may approach Florida by Thursday. The environment could become more favorable for development early next week as an upper air ridge builds across the western Atlantic. Residents in Florida should continue to keep a close eye on this system.

-Another tropical wave stretching from Jamaica to the western Bahamas continues to move to the east. This will bring a chance of showers to the Florida Keys and south Florida tonight and tomorrow. The wave will move into the Gulf of Mexico by Sunday and could organize a bit more as a strong upper air ridge will create a favorable environment for development. Residents in south Texas should keep a close eye on this system.

-90L continues to look like the most impressive of the bunch, but moderate easterly wind shear is creating a less than ideal environment for development. Still, water temperatures in the lower 80s and a moist ambient environment will likely allow for this wave to develop into a tropical depression and tropical storm this weekend. In fact, I would be somewhat surprised if this is not named by the end of the weekend.

The track forecast for 90L remains complicated by the fact that it does not have a true center of circulation. Until this occurs, forecasting the short and long-term track will be very speculative. That being said, the GFS appears to be the outlier at this point with the tropical wave impacting the Caribbean islands. The foreign models keep the wave north of the islands with the European being the furthest north. I am leaning more in like with the 12Z Canadian run that places the system just north of the Lesser Antilles by Thursday morning. By Friday, models agree on the development of a trough across the eastern part of the country but differ on the strength. The European and Japanese models are the strongest with the trough while the GFS is slightly weaker and further east. The trough in eastern Asia this morning that would teleconnect to next weekend looks to be a compromise between the European and GFS solutions. This trough should pull the system northward by next weekend and may pose a threat to the East Coast. Again, this is highly speculative until a true center is defined and intialized properly by numerical guidance. If you live from Miami to Maine, it would be wise to keep a close eye on this system over the next several days.

Afternoon Clouds, Slightly Warmer

The influence of our upper air trough will have completely vanished by this afternoon as a large upper ridge dominates much of the region. Despite the ridge re-establishing its territory today, temperatures aloft only warm slightly compared to yesterday. In fact, highs later today should top out near 92. We'll stay dry again this afternoon with only a few cumulus clouds dotting the sky. By this evening, it appears that we'll be more cloudy than the previous two nights. More importantly, winds will begin to veer to the southeast and moisture will subsequently increase, which should keep low temperatures near 71 tomorrow morning.

The weekend weather looks pretty good. Saturday will be dry with highs in the low to mid 90s. There will be a slight chance for afternoon showers on Sunday afternoon with highs in the lower 90s.

Warm But Less Humid

It's a very pleasant start to the morning with temperatures in the upper 60s to near 70. Skies are crystal clear this morning, but a few afternoon cumulus will likely dot the sky. This afternoon will be warm but nice with highs topping out near 90, and with dew points expected to be in the 60s today, the heat index will not be an issue. Clear skies, light winds, and dry air should allow for temperatures to drop near 67 tomorrow morning.

Mostly Sunny, Less Humid

All the rain and most of the cloud cover has exited to our east and south. However, areas of dense fog exist around the area this morning so be careful on your drive to work or school. The fog should dissipate after 9 a.m. and give way to mostly sunny skies for the remainder of the day. The frontal boundary responsible for the rain is located to our south and will keep us dry today and cause dew points to drop into the 60s by this afternoon. Highs this afternoon will top out near 90, but at least we won't have to contend with the heat index. Skies should be clear this evening along with light winds and dry air. This combination should allow for low temperatures tomorrow morning to drop near 67.

Brief Tropical Thoughts

I'll post a more extensive discussion tomorrow, but I wanted to post a few quick thoughts on the current tropical activity.
-The MJO-related upswing in the main development region has finally resulted in some excitement in the tropics.
-T.D. 2 has shown some signs of becoming better organized this evening as evidenced by the satellite presentation and increase in wind speeds.
-Significant short-term development appears unlikely given the marginal SSTs and the amount of dry air and Saharan dust surrounding the depression. However, a small amount of strengthening could result in the first tropical storm of the year being named (Ana) by tomorrow.
-I get the feeling this system will recurve harmlessly out to sea as it feels a weakness in the ridge by the end of the weekend and early next week.
-Two other waves in the vicinity of the Lesser Antilles bear some watching. However, these waves are encountering a slightly more hostile environment in the eastern Caribbean. Until the South American heat low can relax, development of either of these waves will be of little concern in the short-term.
-The wave to watch may be the one behind T.D. 2. that is emerging off the coast of Africa. Global models indicate this system will develop and could pose a threat to the northern Lesser Antilles next week. I don't like the European model's position at 240 hours; the East Coast should keep a watchful eye on this system over the next week. Of some interest, global models are in agreement with the development of a trough over eastern Asia by the end of this week.

PM Storms, Warm

It's a warm, muggy start to the day thanks to blow off clouds from convection to our north and west. Speaking of muggy, the dew point at Golden Triangle Airport at 11 a.m. yesterday was 81; combined with a temperature of 88 at the time yielded a heat index of 106! We won't have to deal with that kind of steam today as the upper air ridge will be broken down and replaced by an upper trough by this evening. This upper air trough will also allow a cold front to approach the push through the region by this afternoon and evening, respectively. Increased cloud cover and a greater coverage of showers and thunderstorms will be the result of the frontal boundary. In fact, it appears that our best chance for rain will likely be late this afternoon and evening, but a few scattered showers will become possible early this afternoon. The high this afternoon should top out around 91. Rain chances should end by 9 p.m. for the entire area as slightly drier air will be ushered in behind the frontal boundary. A few clouds will still keep temperatures around 72 tomorrow morning.

Isolated Showers, Warm

The upper air ridge influencing our weather could best be described as a dirty ridge as multiple impulses will put big dents in it today. However, these dents will be most noticeable well to our southwest as these locations will have the best chance of rain. I think a few isolated showers and thunderstorms will develop this afternoon, but the coverage should be much less than yesterday. This also means temperatures will be a little warmer than yesterday, but the presence of clouds will keep highs around 92 this afternoon. Dew points will run in the mid 70s this afternoon, and combined with temperatures in the lower 90s, the temperature will feel like it's in the lower 100s at times. Increased cloud cover overnight will likely lead to similar temperatures to this morning so expect a low near 73.

Warm and Dry

Except for a few passing high clouds, skies are clear this morning with temperatures in the lower 70s. There's not much too talk about weather wise today as an upper level ridge will become centered over the region by this evening. A few patchy afternoon cumulus will develop, but the chance of rain today is zero. Despite the fact that the ridge builds overhead, low level temperatures only warm slightly from yesterday. Therefore, highs will probably top out around 93 this afternoon. With dew points falling into the 60s this afternoon, the heat index should not be much of a factor today. Skies should be mostly clear overnight with temperatures dropping to 70 tomorrow morning.

Saturday and Sunday are shaping up to be warm days, especially Saturday as highs should be a degree or two higher than today. Saturday should be dry, but the chance of rain returns Sunday as moisture significantly increases across the area. It doesn't look like a washout by any means, but a few isolated showers are possible Sunday afternoon. Look for highs to top out in the lower 90s on Sunday. Better rain chances still appear to be next week with the arrival of a cold front by midweek.

Patchy Clouds, Warm

A few passing low clouds this morning kept temperatures in the lower 70s for the most part. These clouds should move off to the south shortly and will provide for a mostly sunny morning. Temperatures will quickly warm again this morning and through the afternoon as an upper level ridge reestablishes itself. This time, we'll be closer to the center of the ridge rather than the eastern periphery, which will squash any chance of rain and will allow for some warm temperatures this afternoon. The strong afternoon sun will likely lead to the development of a few patchy cumulus clouds as temperatures manage to top out near 93. With the heat index factored in, it will feel like the temperature is in the upper 90s at times this afternoon. Skies should be clear this evening with temperatures dropping to near 70 by sunrise. The next few days appear to be relatively dry and warm, but rain chances will increase by the middle of next week as a cold front approaches the region.

AM Showers, Afternoon Clearing

Today is one of those rare days where you can throw out every computer model, and instead, use satellite, radar, and a little intuition to forecast. As I mentioned a couple of days ago, being on the eastern periphery of an upper ridge can sometimes yield a few forecasting surprises. That's certainly the case this morning as a dying convective complex that formed across Missouri and Arkansas ahead of a weak cold front overnight continues diving to the south and east. We've dodged the brunt of this complex, but a few light to moderate showers will be possible through most of the morning. I doubt we will have much rain to contend with this afternoon because strong subsidence in the wake of the upper level shortwave will likely squash any widespread development. That being said, an isolated thundershower is not out of the realm of possibility late this afternoon or evening, especially with the aforementioned frontal boundary stalling to our north. The back edge of the clouds is still located across the Bootheel of Missouri, and on its current movement, we'll likely see clearing skies after 1 p.m. The combination of the clouds and rain will keep highs below normal today as we should top out around 86 this afternoon. Skies should be mostly clear this evening as lows dip to near 71 tomorrow morning.

PM Clouds, Toasty

It's quite a warm start to the day with temperatures running in the mid 70s. Temperatures will likely be in the 90s by later this morning, and we'll even top out a few degrees warmer than that this afternoon. Our weather will again be dominated by an upper level ridge with the primary storm track remaining to our north, which will keep any organized convective complexes away from the area. Similar to yesterday, there is a tiny chance of a stay afternoon thundershower. Low level temperatures will warm a couple of degrees compared to yesterday, but afternoon cumulus and high soil moisture will keep us from experiencing any nasty heat. Still, highs will top out near 94 today, but the heat index will hover in the lower 100s at this times afternoon. Clouds will thin out tonight with temperatures dropping to 73 tomorrow morning.

Warming Up

The persistent eastern trough that kept temperatures below normal and precipitation above normal for the last couple of weeks has lifted northward and allowed upper level ridging to take shape over the area. We'll be on the eastern periphery of the ridge and that can always provide a surprise or two in the forecasting department. However, I don't look for any big surprises with the weather today as we should remain mostly sunny throughout the day. We may see a few cirrus overhead but mainly widely scattered afternoon cumulus will be the dominant cloud type. An isolated afternoon shower isn't completely out of the realm of possibility, but the chance of this is almost not worth mentioning. Highs this afternoon will top out near 92, but dew points in the 70s will make the temperature feel like it's over 100 at times later today. We should remain mostly clear overnight except for a few stray clouds with temperatures dropping to near 72 tomorrow morning.

El Nino Responds

No, El Nino didn't technically go anywhere, but it took some vicious easterly shots for about a month, got up off the mat, and is currently on the offensive. A scroll through these various links from CPC (http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml) reveals exactly what the easterly wind burst did to the overall ocean-atmosphere link. Despite SST anomalies generally remaining near 1 C between 160 W and 90 W, slightly cooler SSTs were pulled westward along the South American coast. It is likely this put some dent in the overall warming, especially from 105 W to the South American coast. Furthermore, the deep reservoir of warmer than normal subsurface water that was evident for much of June and July has been significantly depleted. If this warm water below the surface cannot be replenished, this El Nino episode may not last very long.

Running five-day means of SSTs shows that the 29 C isotherm remains near 175 W, which is approximately its location a couple of weeks ago. SST anomalies show weak warming continues across the equatorial Pacific (between 0.5 and 1 C), but only a small pocket of greater than 1 C anomalies is present between 138 W and 118 W. Contributing to this remains stronger than normal trade winds along and north and south of the equator. In the wind speed graphic, note the strong convergence taking place near 170 E; we'll discuss this shortly. The depth and structure of the thermocline shows a weak El Nino signature, but strong warming has taken place in the eastern equatorial Pacific about 50 meters below the surface. If the stronger than normal trades can relax in this area, it's possible this warmer water may rise closer to the surface. This will be something to watch in the coming months as it could have major implications on the location of the warmest anomalies in the equatorial Pacific. The location of the warmest anomalies has been shown to have major variations in precipitation patterns across the U.S. (Hoerling and Kumar 2002).




Global wind signals show that the easterly wind burst has subsided, and in fact, a renewed westerly wind burst began earlier this week with the downturn noted in the SOI. The 30 day average peaked above 10 on July 21 but has now since dropped back to about 1; expect this to go negative again in the next couple of weeks. Updated through July 27, frictional torque was near climatology but is likely stronger, especially with the addition of strong westerly winds in the equatorial western Pacific and in conjunction with the strong Aleutian low. Mountain torque has leveled off about 1 deviation above climatology with positive contributions comings from Eastern Asia and the tropics. This provides further evidence that the Asian monsoon and tropical forcing have been responsible for the global pattern observed in the last week. Relative AAM was near climatology but has likely since risen above climatology, and the tendency of relative AAM spiked to over 3 standard deviations above climatology. The combination of these two reveals that phase space 4 of the GWO was where the global atmosphere was earlier this week. With recent increases in frictional torque and relative AAM, it's likely that the current phase space projection would likely be 5. However, the current global pattern is best depicted by GWO phase 6.






The resurgence of El Nino can be attributed to the strong western Pacific tropical convection. For nearly a month, competing tropical signals were evident across the western Pacific and in association with the Indian monsoon. The later is beginning to shut down as the strongest forcing is taking place in the western Pacific basin, and in fact, satellite and OLR anomalies suggest the convection is centered near 150 E. The energy associated with this tropical convection has been dispersed into the mid-latitudes and will continue to do so for the time being. What does this mean? Any numerical models that don't handle heat (e.g. GFS), have been struggling and will continue to struggle until the tropical forcing is realized.




Synoptic impacts of the tropical forcing for week 1 will be a strengthening of the north Pacific jet by the end of the week, which will result in the development of a western trough, central states ridge, and New England trough. This will allow temperatures in the Pacific Northwest and New England to cool near and slightly below normal while the heat will return to the Southern Plains. Recent rainfall in the Southern Plains will ensure that this heat will be nothing like that experienced in the first half of July. Severe storms will also return to the Northern and Central Plains where the strong westerlies will be located. For our area, temperatures will likely be near to slightly above normal and rainfall will be below normal. For the first half of week 2, this pattern should remain in place with the heat centered slightly further east so this means continued above normal temperatures and below normal precipitation. The flow should flatten out for the later half of week two with temperatures likely backing down to near normal for our area.