Gustav's Last Hurrah

Cuba inflicted more of a beating on Gustav than I thought which is excellent news for Louisiana. However, satellite images along with reconnaissance data indicate that Gustav is becoming better organized late this afternoon. The pressure has dropped about 5 mb since this morning and is now down to 957 mb. The corresponding increase in wind speed will likely occur later tonight as the wind speed usually lags the pressure drop by several hours. I still think Louisiana takes a battering from Gustav but not quite as bad as I originally was forecasting. Regardless, I expect Gustav to be very close to Category 4 status when it makes landfall tomorrow morning. I still wouldn't rule out Gustav becoming a strong Category 4 hurricane if it develops a circular eye and the convection becomes more symmetric. I'll have a big update later this evening

Quick Thoughts

Cuba slightly weakened Gustav as it crossed over the western tip earlier this evening. However, Gustav is back over the very warm waters of the Gulf of Mexico and should re-intensify again shortly. However, wind shear is quite high just to the north of Gustav and may limit significant strengthening until the shear relaxes.

Model guidance has now clustered on an idea of a landfall in south-central or Southeast Louisiana. I have elected to shift my track a bit further east due to the unexpected right of track path Gustav took for much of today and the model agreement. I still feel that the ridge will push Gustav more to the left close to landfall, but I have to include the track today in my ideas. Therefore, I now expect Gustav to make landfall on Monday as a Category 4 hurricane at Marsh Island, LA. More thoughts tomorrow.

Gustov Now a Category 4 Hurricane

This is one of the more remarkable rapid intensification phases I have ever seen. Not from a pressure standpoint but certainly from a wind standpoint. In 24 hours, the minimum pressure has fallen from 984 mb to 945 mb and maximum sustained winds have increased from 70 mph to 145 mph! That's one impressive feat.

Satellite images and reconnaissance data indicate the eye wall has become much more symmetric the last couple of hours, and that has allowed this secondary rapid intensification phase. It's tough to say if the current rapid intensification phase is over because Gustav will soon be interacting with the Isle of Youth and Cuba later today. It's still almost a certainty that Gustav will be stronger this afternoon and could be near Category 5 intensity when it crosses the western tip of Cuba. Unfortunately, Cuba will have very little impact on Gustav and may only weaken the winds by 5-10 mph at the most.

Once in the Gulf of Mexico later tonight, Gustav will either re-acquire or acquire Category 5 status fairly quickly. I wouldn't be surprised to see Gustav become a very powerful Category 5 hurricane with winds up to 170 mph at some point in its life. Even that could be somewhat conservative. I don't think Gustav will be able to sustain that intensity for very long, and I don't think Gustav will be a Category 5 at landfall. Still, it is expected to be a major hurricane at landfall. I'll have another update later this afternoon.

Major Hurricane Gustav Takes Aim on Cuba

After an impressive rapid intensification phase overnight, Gustav is now a Category 3 hurricane with a minimum central pressure of 955 mb and peak winds of 120 mph. Gustav's pressure dropped 33 mb in 24 hours, and it doesn't appear that the current rapid intensification phase is over just yet. Environmental conditions are pristine over the northwest Caribbean, and Gustav is likely to be a Category 4 hurricane as it approaches the western tip of Cuba late tonight.



Gustav is currently moving to the northwest as it has encountered a weakness in the ridge. A strong ridge is forecast to develop on Monday that will turn Gustav more to the left. Just how much to the left has a large impact on exactly where Gustav will make landfall. There is decent model agreement that the ridge will not be strong enough and will cause Gustav to make landfall in Southern Louisiana. I'm still remaining firm in my forecast that the ridge will be stronger than models suggest and will cause Gustav to make landfall near Sabine Pass, TX.

The intensity at landfall is quite problematic at this time. Before that, it still appears that Gustav will probably acquire Category 5 status at some point in the Gulf of Mexico. I don't think it will be able to maintain that intensity all the way to the coast, but the 06Z GFDL suggests it is certainly possible. Let's hope that particular run is not correct! However, water temperatures are still plenty warm near the coast (86 - 89 F) to support a Category 4 or 5 hurricane.

Caution should be used when looking at the Tropical Cyclone Heat Potential product and just assuming that it is not high enough near the coast to support a Category 4 or 5 hurricane. Remember that it is an integration from the top of the sea surface to the depth of the 26 degree Celsius isotherm. The continental shelf off the northern Gulf Coast is extremely shallow and is too shallow to give an accurate measure of TCHP.

Regardless, wind shear is forecast to increase as Gustav approaches the coast and this will certainly limit strengthening and probably cause it to weaken. Another possibility is that Gustav could entrain some dry air as it gets closer to the coast which would certainly act to weaken the system. It's too early to say whether that will happen at this time. In addition to environmental factors affecting intensity, eye wall replacement cycles will also dictate the strength of Gustav. If it is undergoing an eye wall replacement cycle, it will probably be in a weakening trend. These cycles typically take about 24 hours to complete. However, if Gustav has completed an eye wall replacement cycle before landfall, it could actually be strengthening or maintaining its strength at landfall. Eye wall replacement cycles near the time of landfall are impossible to forecast at this time. Conditions are expected to be supportive of at least a Category 3 hurricane at landfall, but I'm still forecasting Gustav to be a weak Category 4 hurricane when it crosses the coast.

Rapid Intensification Underway

It appears that a possible rapid intensification phase has commenced. Earlier today, reconnaissance data indicated a minimum central pressure of 988 mb, but that has dropped to 980 mb as of the latest recon data. Visible and infrared satellite images show Gustav is becoming extremely well organized early this afternoon with multiple feeder bands, excellent outflow, and the appearance of an eye. It should be no surprise if Gustav rapidly intensifies into a major hurricane by tomorrow given the high oceanic heat content, low wind shear, and moist air surrounding the hurricane. The conditions suggest a textbook example of rapid intensification is imminent.




I'll have another update later this evening, which will discuss the threat of Hanna to the United States. It appears that Hanna could be another formidable hurricane next week threatening Florida and the Gulf Coast. It's going to be a long two weeks...

Gustav Moving Past Jamaica, Primed For Explosive Development

Interaction with Jamaica and dry air were the only two negative factors inhibiting Gustav from rapidly intensifying yesterday. Jamaica had very little impact on Tropical Storm Gustav's inner core and only weakened the storm a small amount. Gustav is moving away from the island so that will not be any hindrance to strengthening. Also, the vast expanse of dry air to the north of Gustav yesterday is completely gone this morning. That's ominous news with the environment that Gustav is about to traverse. Noting the satellite presentation of Gustav this morning, it looks like the storm is already beginning to intensify and this may be the initial stages of a rapid intensification phase that will soon commence.



Gustav is very slowly inching its way back into the very warm Caribbean waters, and radar mosaics along with satellite images show that an eye-like feature appears to be developing just west of Jamaica. As of the last reconnaissance data, I note that the pressure has now dropped to 988 mb. This may be the onset of a rapid intensification phase that will likely take place given the low shear (5 knots), the highest oceanic heat content anywhere in Atlantic (SSTs 86-88 F and TCHP 90-130 kJ cm-2), and moist air surrounding Gustav. With the expected environmental conditions favoring rapid intensification, I wouldn't be surprised if Gustav reaches near Category 4 and possibly Category 5 intensity before moving into the Gulf of Mexico early Sunday morning.

The models are split once again on the track of Gustav. Some take Gustav northward to Louisiana while others build the ridge strong and push it back toward Texas. At this point, there is considerable uncertainty in the models, but a NOAA G-IV mission is scheduled later today and this should improve the model divergence tonight. I'm not changing my forecast ideas of a landfall near Sabine Pass, TX. I'll have more later this afternoon.

Gustav Poised to Explode

After appearing that Gustav had nearly died last night, it is alive and well this morning. Indeed, for sometime last evening, it appeared that Haiti had severely disrupted the circulation enough that Gustav might not recover for a couple of days. However, a burst of convection formed near Jamaica and the center evidently re-formed near that area. In fact, Gustav looks incredibly impressive on satellite imagery this morning with intense convection clustered near the center. Additionally, the S-shaped appearance suggests that strong outflow jets are beginning to form, and this is a sign that Gustav is poised to strengthen quite rapidly once it gets past Jamaica.


A strong ridge is located to the northwest of Gustav and even steered the storm southwest overnight. Its current motion continues WSW and this should continue until this afternoon. Joe Bastardi made an excellent call on this yesterday. The strong ridge should steer Gustav west and eventually WNW for the next 48-60 hours. After that time, Gustav should be on the southwest side of the ridge and will begin to turn more to the NW. Despite the recent model flip-flops, I'm still not changing my landfall area. In fact, at this point, I'm leaning a bit closer to a Rita type landfall rather than a Galveston landfall. My thinking is a compromise of the 06Z HWRF and 00Z NOGAPS solutions.

Short-term intensity issues revolve around interaction with Jamaica and some dry air to the north of Gustav. Otherwise, the environment looks highly supportive of strengthening. However, land interaction and dry air are certainly two impediments that will quickly halt any strengthening. In fact, I wouldn't be surprise to see the mountains of Jamaica have some negative impact on the intensity. While not as rugged as Haiti, Jamaica's elevation (3,000-5,000 ft) is still high enough to disrupt the core of Gustav. I don't think Gustav will take nearly the beating as it did by interacting with Haiti. Also, the dry air to the north is of some concern in the short-term as well. If any dry air is entrained into the center, Gustav will probably weaken somewhat. However, if Gustav is able to keep the dry air away from its center, Jamaica will be the only impediment to short-term rapid intensification.

After Gustav passes by Jamaica early tomorrow morning, the environment appears supportive of intensification. However, the GFS continues to insist that wind shear may be high enough to limit rapid intensification. I'm not buying that given that Gustav will be underneath a strong anticyclone and high oceanic heat content beneath it. The dry air should moisten up by tomorrow and this all argues for rapid intensification by Saturday. Given that Gustav will traverse the loop current, a reservoir of very warm and deep water, it's very possible it could be a Category 4 hurricane when it enters the Gulf of Mexico on Sunday.

I still think Gustav attains Category 5 status in the Gulf of Mexico by the end of the weekend. It's still impossible to forecast a specific intensity at landfall due to eye wall replacement cycles. Additionally, increased wind shear may even weaken Gustav before it makes landfall with the U.S. However, I still feel that Gustav makes landfall as a Category 4 hurricane near Sabine Pass, TX on Tuesday.


Recently upgraded Tropical Storm Hanna may also pose a threat to the U.S. East Coast next week. It looks very impressive now and it also could become a formidable hurricane down the road. If that wasn't enough, a large flare up of convection in the Bay of Campeche occurred overnight. However, it shouldn't strengthen much since it is so close to land. Elsewhere, another tropical wave is located over the Eastern Atlantic, but it won't pose much of a threat until it moves west into warmer waters. Finally, another easterly wave has emerged off the coast of Africa and it may develop in a couple of days. I'll be happy when the current Madden-Julian burst leaves the Atlantic!

Models Shifting East

Haiti has inflicted quite a toll on Gustav over the last 24 hours or so, and in fact, Gustav is now a tropical storm with winds of 60 mph. The center of Gustav is now back over the warm water, but it will have to separate itself from Haiti before significant strengthening can resume. This should begin tomorrow morning.

Over the course of the last few runs, all of the dynamical guidance has shifted its tracks of Gustrav to the right, including the far left European and UKMET. However, I'm still not jumping on board with the NHC and the majority of the global models that move Gustav east of 90 degree West. A strong ridge is building over Gustav and should move the storm off to the west and, at times, WNW over the next 2-3 days. The models begin to diverge significantly in this time frame with some turning Gustav to the northwest as the ridge breaks down, and others keep the ridge strong and continue moving Gustav to the WNW.

My thoughts haven't changed much from yesterday, and I still am favoring the scenario of the ridge remaining stronger as suggested by the European, UKMET, Canadian, and Japanese models. The ridge should begin to weaken slightly by Labor Day and will then turn Gustav more to the northwest. Texas is still my landfall idea and particularly the upper Texas Coast from Galveston to the Sabine River.

My thoughts on the intensity have changed a little, mostly with regard to the short-term period. It appears that Haiti may have disrupted the core somewhat, and I think this will limit rapid intensification for the next 24-36 hours. After this period, Gustav is expected to be in an environment conducive to strengthening. High ocenic heat content and a moist ambient environment will all contribute to Gustav modestly strengthening. However, it appears that the only factor that may limit a rapid intensification phase before Friday evening would be moderate wind shear (15-20 knots). After Friday evening, wind shear is forecast to weaken below 5 knots. Therefore, the stage should be set by Saturday for Gustav to undergo rapid intensification, and it's quite possible it could be a Category 4 hurricane as it moves into the southern Gulf of Mexico Saturday evening.

While the thermodynamic state of the ocean isn't quite as favorable in the central and western Gulf as it is the northwest Caribbean, it is still capable of supporting a Category 5 hurricane. With low wind shear, moist air, and a high oceanic heat content in the Gulf, I think that Gustav will attain Category 5 status as some point. Also, eye wall replacement cycles will dictate fluctuations in intensity when Gustav does get that strong. As Gustav approaches the U.S. mainland, an increase in wind shear could limit strengthening and probably weaken it some. Regardless, I still feel that Gustav will be a Category 4 hurricane at landfall.

I'll have another update tomorrow unless something significant changes.

Big Trouble Brewing in Caribbean

After shedding nearly every environmental obstacle in its path, Gustav was finally named yesterday. After traversing some very warm, deep water, Gustav has strengthened appreciably in the last 24 hours and is now a Category 1 hurricane with 90 mph winds, despite a rather high central pressure of 981 mb. Additional strengthening is likely until Gustav moves over Southern Haiti later today.

A trough in the Western Atlantic was responsible for pulling Gustav more to the north and northwest, but a strong ridge is forecast to build over Gustav tomorrow and should push it more to the west. I will actually give major props to the GFDL for its handling of Gustav so far. Usually, it and the GFS are too far to the right because they break down the ridge too quickly. The GFS has been quite poor thus far in its handling of Gustav, but the GFDL has been very impressive with its track and intensity. It's not very often I get to brag on the American models, but the GFDL is performing extremely well. However, let's hope the GFDL's excellent performance comes to a screetching halt. More on that in a moment.

Most of the model guidance has shifted much further to the left and all are in decent agreement that Gustav generally stays south of Cuba. This will have major implications on the future intensity. The models move Gustav south of Cuba and then there is some slight disagreement about whether Gustav clips the western tip of Cuba or stays over the open water between Cuba and the Yucatan. Given that Gustav will probably be a very significant hurricane by Friday, I feel that a tremendous amount of extra heat will be pumped into the ridge and Gustav will probably go even more left than what the models are currently predicting. At this point, I think it will split the Yucatan and Cuba, but it's certainly possible that it could even clip the Yucatan. After the encounter with Yucatan or Cuba, Gustav will emerge in the Gulf of Mexico.

This is a more ominous scenario than when I was worried that Fay would impact the northern Gulf Coast. I expected Fay to stay over more of the eastern half of the Gulf of Mexico, but it appears that Gustav will unfortunately stay over more of the power keg of the central and western half of the Gulf.

By Saturday, the models are in agreement that Gustav will turn more to the northwest as a trough in the Central U.S. breaks down the subtropical ridge. I still feel that the ridge will be a bit stronger as depicted by the Canadian and will push Gustav more to the left than what is currently being forecast. However, I'm not leaning as far left as the European or UKMET. The ultimate destination to me looks like a northwest Gulf of Mexico landfall next week. The 06Z GFDL is particularly ominous as it has Gustav threatening Louisana by late Sunday as a strong Category 4 hurricane. Let's hope that is wrong!

The short-term intensity of Gustav depends on a couple of things. Any interaction with the mountainous terrain of Haiti could disrupt the core and will prevent significant strengthening for a few days. Also, any interaction with the rugged terrain of Eastern Cuba could also have a negative impact on the strength. At this point I feel that Haiti may temporarily disrupt the circulation, but I still feel that Gustav will only weaken slightly. Given the oceanic heat content in the path of Gustav, a building upper-level anticyclone, and moist ambient air surrounding the hurricane, all the conditions appear pristine for rapid intensification and support for a Category 5 hurricane in the northwest Caribbean and southern Gulf of Mexico by the end of the weekend. It's never a good thing when there is a Western Pacific environment in the Caribbean and Gulf of Mexico. It's a recipe for a catastrophic hurricane.

Expected conditions in the Gulf of Mexico will also favor the maintenance of a Category 4 or 5 hurricane with moist ambient air, low shear, and high heat content. It appears that trochoidal oscillations and eye wall replacement cycles will dictate the fluctuations in strength when Gustav reaches that intensity. Due to that, it's impossible to forecast the exact landfall intensity this far out, but environmental conditions are expected to support at least a Category 4 hurricane up to landfall.

To summarize, I think Gustav will be a Category 5 hurricane at some point by the end of the weekend as it moves into the southern Gulf of Mexico. At that point, I feel that the ridge will break down by Monday and begin to turn Gustav toward the Texas coast. Gustav should maintain Category 4-5 intensity for quite some time and could be a Category 4 hurricane at landfall in Texas next week.

This doesn't even begin to touch on the potential for several more tropical cyclones in the next few days. More on that later!

Teleconnections and Tropical Thoughts

Greg Nordstrom has posted a good discussion on applying the teleconnection of wave patterns in Asia to the United States. Check it out if you want to learn how to improve your long range forecasting skills.

Fay made its third landfall earlier this afternoon on the eastern coast of Florida. Fay is also beginning to move west very slowly as the ridge begins to build in. What's really crazy is that Fay may actually make a fourth landfall in the Florida Panhandle tomorrow night! Model guidance has slowly shifted the track of Fay a bit further south, and it appears more likely that she may briefly move over the Gulf of Mexico. With such a slow moving tropical system, this is exactly what the doctor ordered for the drought-plagued South!

Many people don't realize that the South is not as wet as you would expect. A good portion of the South's total annual rainfall (~25%) comes from tropical systems. Whenever the South experiences a prolonged drought, you can probably bet that tropical activity has been minimal. After 2005, most areas in the South have seen very little tropical activity (2006 and 2007), and it's no coincidence that severe drought conditions have been common in many places the last few years. It does appear that is changing this year, but the tropical rains may come with a steep price.

I'll have more later this evening...

Fay Moves Over Water and Lessons Learned

Sorry for the lack of delays the last couple of days. It's been a little hectic to keep up with the weather with classes beginning. After making landfall in Southwest Florida early Tuesday morning, Fay unexpectedly strengthened over the peninsula. This was not the result of the pressure gradient tightening commonly seen with landfalling systems. In fact, Fay's central pressure actually dropped and maintained itself near 986 mb for several hours.

It will require some research, but I will go back and investigate why this actually occurred. My initial thought is that the swampy, marshy soils in South Florida were fairly wet and acted as a temporary fuel source. That's pure speculation at this point, but it should be an interesting study nonetheless.


Even for a tropical storm, Fay still looks quite impressive on satellite and radar imagery. Currently, Fay has moved into the warm Atlantic waters just to the northeast of Titusville. Radar loops don't show a lot of movement with Fay, and as long as Fay stays over water, strengthening is possible. In fact, it wouldn't take much for Fay to regain hurricane strength. Still, the proximity to land, moderate wind shear, and potential upwelling should prevent significant strengthening.


Models all unanimously turn Fay back to the west as a strong upper-level ridge and associated surface high pressure establishes itself over the Eastern U.S. The models are also unanimous in taking Fay across Northern Florida Thursday and Friday, but there is some slight model divergence late Friday. Most models continue to take Fay west and a little northwest around the periphery of the subtropical ridge, but a few models actually do think Fay makes it back into the Gulf of Mexico. While it wouldn't surprise me to see this happen, I'm still leaning along the lines that Fay does stay over land once it moves back west. This would be excellent news for some of the drought-stricken areas in the Deep South.

This has been a frustrating storm to forecast the track, and it doesn't help matters that I made a critical error in my track forecast. If you'll remember back to last Thursday's post, I spoke in some detail about how I felt confident the U.S. would be hit due to the trough/ridge pattern in Eastern Asia earlier in the week. A large ridge was present over Eastern Asia on Monday, and this typically corresponds to a ridge of the Eastern U.S. about 9-10 days later. That matches up pretty well with the current trough/ridge pattern in the U.S. This is where I made my mistake. Before the ridge built into Eastern Asia last Monday, a trough had just lifted out over the weekend. This should have keyed me in on the idea that a potential tropical system in the Atlantic basin would be pulled poleward due to the departing trough. However, behind the departing trough, any tropical system would be pushed back to the west with the building ridge. This is exactly what has happened and is expected to happen with Fay, and I'm disappointed in myself for not correctly applying the teleconnection taught by Doug Gillham.

Fay Turning North

Judging by satellite images this morning, it is now apparent that the subtropical ridge has been breached and has caused Fay to turn more to the NNW. Model guidance is now beginning to cluster along the western coast of Florida, but let me throw out a word of caution about that. Any small deviation to the left of Fay will cause the landfall to be much further north along the coast.

The satellite presentation of Fay is drastically improving, and it appears that Fay will be poised to undergo intensification in the Gulf of Mexico. I promise I'll have an update later this morning.

New Thoughts

After watching Fay and reviewing the latest guidance, my original forecast of a Category 1 hurricane landfall in South Florida needs to be changed. I felt confident if Fay moved over Eastern Cuba that South Florida would be the likely destination. Now, however, Fay is near the southeastern coast of Cuba and is moving WNW. This pushes my landfall idea further west, and my current thinking is that Fay makes landfall in the big bend near Apalachicola as a weakening Category 3 hurricane. My thoughts on why later this afternoon...

Interesting Solution

Want to see something really interesting? Check out the image below that shows the GFS ensemble tracks of Fay. Now go check the latest satellite loop of Fay and compare the two. I don't think the scenario laid out by the GFS ensemble members, which have shown remarkable consistency in this scenario, is completely bogus. In fact, I'm beginning to seriously consider whether Fay does stay much further south than guidance given the obvious strength of the ridge and possibly runs between the Yucatan and Cuba or grazes over Western Cuba. Either way would be potentially catastrophic given the expected ocean thermodynamic environment, low wind shear, and high ambient moisture surrounding Fay.


Let me stress again that I'm still not changing my forecast until I see whether Fay stays south of Cuba, which appears to becoming more likely, or moves across Eastern Cuba. 12Z guidance should be rolling in soon so I'll have an update later this morning.

Models Shifting West

The early runs of the 00Z guidance suite is beginning to roll in and all are in agreement that Fay will impact the northern Gulf Coast or Western Florida. I'm still not going to change my forecast until I see whether Fay stays south of Cuba or moves over Eastern Cuba. That will have a major impact on my ideas for landfall and intensity. I'll have another update in the morning.

Tropical Storm Fay Develops

Aircraft data indicates that Tropical Storm Fay has officially developed. The newest suite of model guidance has again shifted the track a little more left. This is more in line with my previous thinking, but I'm worried I may have to shift my track even further left given the current progression of Fay.



This brings up an interesting dilemma. South Florida is very narrow from east to west (~50 miles). Given the expected motion of Fay as it approaches Florida, even a small shift of the track to the west could mean a landfall in the northern Gulf of Mexico (as suggested by the 12Z GFDL). If this scenario occurs, it could mean BIG problems for the northern Gulf Coast. Instead of a Category 1 hurricane in South Florida, we could be dealing with a potentially devastating Category 4 hurricane in the Florida Panhandle.

I want to watch the progression of Fay this evening before I shift my track a little more left. Unfortunately, I get a sinking feeling as Fay continues to move west. The more Fay moves to the left, the greater the potential for a disaster.

Where and How Strong?

Those are going to be the main questions when "Fay" is upgraded which is likely to happen this afternoon. Those are both excellent questions, and I'll try provide my thoughts on the track and intensity. Overnight, the center tried to reorganized itself near the strongest convection, and it even appeared that the center reformed slightly to the southwest overnight. Currently, the main center of "Fay", judging by radar, appears to be approaching the western tip of the Dominican Republic. If anything, you can even argue that the system has take a slightly south of west jog in the last few hours.

Given the placement of the trough off the East Coast, I'm somewhat surprised that the system as a whole has move entirely westward. The NHC's sea surface analysis suggests that the subtropical ridge has still not been breached, but that should occur once "Fay" passes Hispaniola. At that time, "Fay" should begin to turn more WNW. Model guidance is in excellent agreement with this track, and "Fay" will probably cross over the hilly terrain of Western Cuba. Once over western Cuba, the eastern U.S. trough is still forecast to be in place. This will cause "Fay" to turn NW and emerge over the Florida Straits by early Monday. I'm thinking that "Fay" will spend a longer residence time over Cuba as suggested by the 12Z Canadian, 00Z NOGAPS, and 12Z GFS (though not quite as far south).

Once "Fay" emerges over the Florida Straits, it should continue to move NW along the western periphery of the subtropical high. The large ridge that I was originally thinking would turn the system back west appears like it will arrive too late. At this point, I'm leaning toward the solution that "Fay" will be approaching the Keys and South Florida Tuesday evening. Shortly after landfall, the system should begin to move northward and move through Florida while the new ridge builds in.

Another interesting idea is what happens to "Fay" after landfall. When the ridge does build in, it's a real possibility that "Fay" could move in the Gulf of Mexico. I don't want to get real specific at this point, but this is certainly a possibility.

The track that I am leaning towards at this point would seem to be "good" for Florida. A longer residence time over the higher elevations of Hispaniola and Cuba will keep "Fay" from strengthening. Only when it moves over the very warm waters of the Florida Straits will "Fay" be able to strengthen. If this occurs, it shouldn't have a very long period over water. Still, the oceanic heat content between Cuba and Florida is quite high with SSTs between 87 F and 89F and tropical cyclone heat potential values around 80 kJ cm-2. "Fay" will also move over the Loop Current and this will only serve to add to the high thermodynamic state of the ocean. Unquestionably, the thermodynamic state of the ocean supports rapid intensification once "Fay" does emerge back over water.

While current wind shear is very low over "Fay", shear is forecast to increase slightly as it approaches Florida. However, if the 12Z NAM is correct, a jet streak to the north could actually provide an enhanced outflow channel and help serve for rapid intensification. Even if this doesn't occur, wind shear will likely be between 10-15 knots near landfall. This is still supportive of intensification but may limit the rapid intensification potential. Given the data I have reviewed, I think that "Fay" will make landfall as a Category 1 hurricane in South Florida.

My forecast is based on current data and trends with the system. If there are significant changes to the current track of "Fay" my forecast is likely to change. I'll have another post when "Fay" is actually named.

"Tropical Storm Fay"

I simply can't believe 92L has not been classified as at least a tropical depression. This is the best looking tropical wave I have ever seen that is not at least a classified as a depression. While I don't want to spend this discussion ranting and raving, I do feel there is scientific evidence that points to the tropical wave at least being upgraded to a tropical depression and even being named. A QuickSCAT pass this morning showed a closed circulation with the wave, San Juan radar has shown a closed circulation since last night, visible satellite imagery shows circular banding, and the DVORAK intensity estimates are at 2.5. This is sufficient data to at least warrant this wave being upgraded to a tropical depression. I even feel strongly enough at this point that there is enough data to upgrade the wave to Tropical Storm Fay.


This may all be a moot point later today as "Fay" will move over the rugged terrain of Hispaniola which will disrupt the circulation. With "Fay" being a weak storm as opposed to a hurricane with a well-defined core, it's possible that Hispaniola may not have a tremendous affect on the storm. Weaker cores are usually less affected by land and terrain than well-defined cores, and I think this will be the case with "Fay". Regardless, weakening is inevitable as "Fay" passes over Hispaniola later today.

I'll have another update later today.

92L Update

After taking a beating by cool waters, high wind shear, and dry air, 92L has survived and is beginning to look much more organized. In fact, satellite estimates and presentation show that 92L is on the verge of becoming the sixth tropical depression of the season. A healthy area of thunderstorms remains clustered near the center, and it even appears that deeper convection is trying to develop near the center this morning. Additionally, the wave's outflow has vastly improved as wind shear has relaxed over the past 18-24 hours. Still, about 20 knots of shear remains on the far western periphery of the wave, and this is forecast to decrease throughout today and tomorrow. By this time tomorrow, the tropical wave should reside in an environment of weak shear (~10 knots).



The main impetus for development seems to be dry air that still surrounds the wave. However, the wave has managed to prevent infiltration of dry air into its center and disrupt the strong convective activity. If this continues to be the case, there is virtually nothing that can hinder 92L from becoming a tropical depression later today or tomorrow. SSTs are near 82 F but should increase to 84 F by tomorrow. Combined with tropical cyclone heat potential values near 50 kJ cm-2, modest strengthening of this system is likely once the wind shear relaxes and as long as dry air remains away from the center. Another potential caveat to strengthening would be any interaction with the higher terrain of Hispaniola. The mountains could act to tear up the circulation and prevent intensification.

I still prefer not to speculate on the exact track of this wave until a true center is formed and confirmed by the Hurricane Hunters. However, model guidance suggests that the wave should move to the WNW as it begins to feel the effects of a trough off the U.S. East Coast. Given the presence of this trough, I think the wave will move north of the Caribbean islands and be approaching the Bahamas by Saturday night. By the end of the weekend, the trough will also beging to lift out and be replaced by a ridge. This ridge may ultimately drive the system into Florida early next week.


Using the trough/ridge pattern in Japan back on Monday, this would suggest that a ridge should be located in the Eastern U.S. by Tuesday or Wednesday next week. This logic would suggest more of a left track than what the current models are currently forecasting. Again, I don't want to get specific with model tracks at this point, but I still feel strongly that Florida is at great risk of a landfalling hurricane early next week. I'll have another update when 92L becomes a depression.

92L Still Struggling

The tropical wave that has moved across the Atlantic has struggled to develop when it has seemed poised to become a tropical depression. Cool sea surface temperatures, dry air and dust, and moderate wind shear have ultimately suppressed development thus far. However, satellite images show that the wave has undergone a burst of convection today and may slowly be showing signs of organization. Still, wind shear is a bit high on the west side of the wave and is currently preventing any outflow associated with the deep convection. This wind shear is forecast to decrease over the next 24 hours and should promote better outflow as the wave approaches the Lesser Antilles. Additionally, SSTs should warm about 2 C in the next 24 hours and should provide more potential for develop. The cool SSTs that wave has encountered thus far can be attributed to a prolonged period of dust from the Saharan Air Layer. This increase in dust that has been observed has prevented good heating of the waters and has resulted in lower than normal temperatures.

The main inhibiting factor still appears to be the dry ambient air associated with the SAL. This has periodically prevented sustained deep convection near the center. Until the environment is able to moisten around the wave, it's possible that this could significantly hinder development. This is likely to occur in the next few days.

It's tough to discuss the track of the wave at this time since a true center has not formed. However, computer models are generally unanimous on moving the wave just north of Puerto Rico, Hispanoila, and Cuba. Regardless, the tropical wave should move around the southern periphery of a strong subtropical high pressure center. It's even possible the wave could even flirt with the islands and this could further disrupt the strengthening and development. The ultimate destination could place the U.S. in danger of a landfall next week. Using teleconnections, a strong ridge is in place in Eastern Asia and is what really worries me about a U.S. landfall. It's too early to pinpoint a definitive track, but I'll discuss this when the wave develops a true center.

To sum up, I think the tropical wave will finally begin to develop tomorrow, but significant strengthening will likely be hampered until the weekend. Residents of South Florida need to pay very close attention to this wave over the next few days.

Tropics Heating Up

The brief lull in the tropical activity appears likely to end abruptly. Two main areas of disturbed weather show up on satellite images this morning, but computer models insist other areas may need to be watched in the next week. I'll have a big tropical update later today!