Tropical Tidbits from the Tundra

Gustav and Hanna, the terrible twins

By: Levi32, 7:54 PM GMT on August 29, 2008

Tropical Storm Gustav 11am EST:

Gustav has finally cleared Jamaica after weakening a bit yesterday. He is now moving WNW but in the process of turning towards the NW around the southern periphery of the high to his north this morning. The models are now in good agreement on a track over western Cuba in 36 hours, and I agree. Thereafter the picture becomes murky, as the models still diverge a great deal in the northern GOM. Most of Gustav's end game will depend on a high moving over the Great Lakes in 4-5 days. If this high ridges southwestward far enough, it could stall or turn Gustav towards the west just off the coast and greatly affect his final landfall location. If this high does not extend far enough south, Gustav will blast NNW without stopping. Currently I am still leaning towards the left, as I think the high will indeed come into play towards the end. A landfall in western Louisiana or near the Texas border seems likely to me here, but it is still way too far out to speculate, as Gustav still poses a threat to a large portion of the gulf coast. Everybody from Texas to the Florida Panhandle should be preparing for a hurricane to be in their vicinity early next week.

Gustav is about to give us lesson 1-01 in how to strengthen. He is going to be moving over the extremely warm waters of the NW Caribbean for the next 24-36 hours, and with absolutely beautiful outflow due to an anticyclone situated above him, I expect significant if not explosive deepening from Gustav today and tomorrow. This may not begin right away, as it is my sense from looking at satellite imagery that Gustav has some work to do on his core after his interactions with Jamaica. It is very possible that Gustav will become a major hurricane before crossing western Cuba, but the Cayman Islands will only get a 1 or a 2. Cuba will only be a speed-bump for Gustav, and he will likely remain a major 3 or 4 hurricane in the GOM. The intensity forecast for Gustav's eventual landfall is also very problematic and still too far out to speculate on. An upper trough currently over the GOM is forecast to retrograde westward as Gustav noses into the area, but it is unclear at this time how far the trough will move. If the trough doesn't move much it could mean moderate SW shear over Gustav before landfall, which may serve to weaken him a bit. Gustav will also be constantly enlarging right up until landfall, and will be quite a monster size-wize. The bottom line here is there is going to be a large major hurricane threat to the northern gulf coast in 3-4 days, and everybody should be prepared.

We shall see what happens!

^Click for loop^


Tropical Storm Hanna 11am EST:

After struggling majorly yesterday, and "taking her clothes off" as Bob put it, Hanna has made an effort and getting re-dressed this morning, and she may be putting on her Sunday best. The COC was briefly exposed earlier this morning, but new convection keeps forming directly over and east of the center, in the face of the ULL to her west, which has finally begun to move as the models forecasted. This ULL is responsible for the westerly shear impinging upon Hanna, and should slowly weaken and move off to the west, allowing Hanna to finally get her act together. Once the ULL is out of the way I think we could see Hanna intensify quite nicely to a Cat 2 or 3 hurricane in 3-4 days. Beyond this point the intensity will largely depend on a trough dropping off the east coast that may inflict strong westerly shear again over Hanna, in possible combination with Gustav's outflow channel.

The other interesting thing is the southerly flow on the back side of this trough and Gustav's outflow are going to end up squashing Hanna southward, stopping her NW progress in 4 days. The models are greatly diverged here as well, and it is really way too far out to think about where Hanna may make landfall. Right now I think the Bahamas will get a battering from a slow-moving Hanna, but it is still unclear how strong she may be at that time. Beyond that Hanna may hit Cuba from the north (wow) or turn NW towards the SE coast, or even move across Florida or through the straights and into the GOM for a 2nd hit. This could be a potentially wild situation with 2 serious hurricanes aiming for the US in the same week. It would be the quickest 1-2 punch in recorded history, but it's too soon to say right now. The Bahamas at least right now should be prepared for a hurricane in their ballpark in 4-5 days.

We shall see what happens!

Gustav pounding Haiti

By: Levi32, 4:39 PM GMT on August 27, 2008

The high mountains of western Haiti have weakened Gustav to a TS overnight. Gustav decided to pull a Fay, and slowed to 4mph while moving almost due west across the length of the peninsula, which has greatly disrupted his circulation. Later this afternoon and tonight Gustav will finally get free of Haiti and begin the restrengthening process. Right now all systems are go for major intensification while Gustav is south of Cuba, with the only inhibiting factor that I can see being restricted outflow in the NW quad and light northerly shear due to Gustav still being east of the upper-level high in the western Caribbean. The GFDL and HWRF models turn Gustav into a monster in the GOM, which is entirely possible if the upper-level environment is favorable, but that is too far out to speculate on right now. We'll cross each bridge as we come to it. Right now I like the NHC idea of bringing this to a major hurricane by 72 hours south of western Cuba.

The track forecast reasoning remains unchanged. The trough which pulled Gustav NW yesterday is moving out of the way, allowing a high to build in from the west, which will turn Gustav to the west or WSW today. Gustav will continue to follow the periphery of this high south of Cuba, and then a weakness in the GOM will cause Gustav to turn WNW and eventually NW, over or near the western tip of Cuba, and into the GOM. Yesterday the NOGAPS and ECMWF models were taking Gustav into the Yucatan Peninsula, not seeing the weakness in the gulf. The NOGAPS no longer has this solution, and the 0z ECMWF last night also showed an eastward shift, still bringing Gustav close to the Yucatan, but much further east and up towards Louisiana in the GOM.

The GOM forecast is still very difficult right now, as it's still 4-5 days out and it is worthless trying to forecast a landfall location at this point. That said, I honestly don't think this is a Florida problem, but rather a problem further west. Right now the models are mostly aiming at Louisiana, but remember good 'ole Fay? The models jump everywhere folks, so we can't jump all over Louisiana just yet. If you really want my opinion, I am leaning towards eastern Texas and western Louisiana, for reasons that I will go over tomorrow. Everyone along the gulf coast needs to be prepared for a major hurricane hit in 5-6 days. I do believe this is going to be our first US major hurricane landfall of the 2008 season, and hopefully our last, but everyone should be preparing for a nasty storm popping into the GOM this weekend. Residents along the entire length of Cuba also need to be prepared for hurricane and TS conditions over the next 3 days, as well as Jamaica and the Cayman Islands.

We shall see what happens!

^Click for loop^


In other news:

95L is sneaking up on us getting its act together northeast of the Antilles Islands. This system has been under tremendous shear, but upper-level conditions are slowly improving, and 95L will be in a favorable area for development in a couple days. There is still a weak circulation at the surface and plenty of thunderstorms are going off this morning. The ECMWF model blows this thing out in the Bahamas, and when the Euro jumps on a system I usually pay attention, so keep this one in your sights over the next few days.

Gustav and 95L are also probably only the first in a whole train of systems coming across the Atlantic over the next couple weeks. Our MJO pulse has arrived, and we are entering the very peak of the hurricane season. The track race has begun, so get ready for a busy time!

Gustav to cause problems

By: Levi32, 4:26 PM GMT on August 26, 2008

Been gone for 4 days, WOW so much happened lol.

First glance at the map here I see Gustav of course, a Humberto-type system which intensified very rapidly from TD to hurricane yesterday. Honestly this surprises me given Gustav's satellite appearance this morning, which really isn't that great. The outflow is marginal but non-existent in the NW and N sides because of an upper trough to the north, which is also generating 10-15kts of shear over Gustav. The convective structure is ragged, and the eye reported by the hurricane-hunters is not showing up yet on visible satellite imagery. I have a feeling Gustav's impressive burst of intensification was likely due to his size, because small systems like this don't need very much to get going, as we saw with Humberto.

Alright, so for now Gustav doesn't have the best of environments, but within 48 hours that is going to change. The upper trough to the north is on its way out, and Gustav will soon be moving under an anticyclone in the Caribbean. This will allow for good venting of air out of the top of the system, allowing surface air pressure to lower, and Gustav will likely strengthen. This will probably cause Gustav to get much larger as well, so don't expect him to remain a small beast for long. Gustav is also moving through some of the highest heat content in the Atlantic Ocean, so he will probably strengthen whenever he's over water, with the only weakening phases during Eye Wall Replacement Cycles. Gustav will be moving over the western tip of Haiti today, which will probably knock him down a bit, but look for re-strengthening very soon after he gets away from Haiti's mountains. There is a chance Gustav could also interact with Cuba, which would severely hamper intensification, but at this time that scenario doesn't appear likely to me. The more likely situation is Gustav becoming a major hurricane between Cuba and Jamaica and then remaining a major hurricane for a while thereafter, but it is uncertain what Gustav's intensity will be after that point.

Where will he go? A very important question with this storm. I like the NHC forecast this morning, which has Gustav crossing western Haiti and then turning west to the south of Cuba as the high builds back in to the north. Further down the road is where things get messy. The models are forecasting a huge high to dominate the eastern US over the next 5 days, with a trough coming through the central US between 3 and 5 days. The question is whether this trough will be strong enough to turn Gustav to the north passing near western Cuba and then into the GOM (GFDL, HWRF, GFS) or will the ridge keep Gustav on a westward track into the Yucatan and then into the western GOM (UKMET, ECMWF). Right now I am inclined to go with the former solution. My reason for this is that Gustav will likely be a major hurricane at this point in his life, and he will turn into any small weakness to his north. I believe there will be at least some kink in the high here, and Gustav will take it. The NHC 4-5 day track shows this, and you can see how even a small change to a WNW course will take Gustav through the Yucatan Channel or over western Cuba. Beyond this point the entire GOM opens up, and Gustav could threaten anybody, very possibly as a major hurricane, and yes this could result in a hit on the oil industry as well. Everybody in Cuba, Mexico, and the entire US gulf coast should keep a close eye on Gustav over the next week, as he will probably be a major problem for somebody.

We shall see what happens!

^Click for loop^

Fay continues to puzzle!

By: Levi32, 3:50 PM GMT on August 19, 2008

Afternoon 5pm EST Update:

Tropical Storm Fay is continuing to play the roll of "joker" as Dr. Master's has dubbed it, and has really confused forecasters both here and at the NHC over the last 24 hours. After more than 12 hours being inland over Florida, Fay continues to hold her intensity and may even still be strengthening. Her eye has remained intact and well-defined, with a nearly complete eye wall. Fay's structure has never looked better, and her pressure actually fell several millibars after landfall, and has been holding steady ever since. This will be a lovely puzzle to solve in the post-storm analysis, but my best guess for now would be that this is a lesson in how much a conducive atmospheric environment can affect a hurricane's intensity. The Everglades also probably helped Fay, as they are flat and wet, and probably gave Fay that little extra energy to keep going. But Fay isn't in the Everglades anymore, and she's still going! LOL.

I'm going to do what I don't like doing, because continuity is important in successive forecasts, but I am going to change my forecast reasoning this afternoon. It is appearing more and more likely to me that Fay will make a sharp turn to the west as the models are predicting, with the exception of the GFDL. This would give Fay a good chance of emerging back across Florida into the northern GOM, and making a run at the gulf coast somewhere. The ridge over the SE is building back in fairly fast, and the trough will start losing its influence on Fay very soon. For now Fay is still slowly moving NNE, and I believe she will make it off the east coast of Florida near or just north of Melbourne, before turning back west. It is unclear how much time Fay will have over the Atlantic, but with Fay's performance over land, any time spent over water will probably result in intensification into a hurricane.

Everybody from SC to Louisiana needs to watch Fay closely over the next few days, as this storm could easily become a formidable hurricane over either the Atlantic or GOM. Of course she could just as easily turn inland right away over northern Florida and die over the SE lol..but who knows...all we can do is give it our best and appreciate how hard the weather really is to forecast. Everybody stay safe during this storm!

We shall see what happens!

^Click for loop^

Fay approaching Florida

By: Levi32, 3:48 PM GMT on August 18, 2008

Tropical Storm Fay has emerged in the Florida Straights after crossing central Cuba last night. The storm got really messed up last night with several surface centers decoupling from the mid-level center, but this morning Fay looks to be vertically stacked again. Organization has deteriorated due to all the land interaction Fay has had over the last few days, but Fay could still strengthen into a hurricane before hitting Florida. The anticylone previously situated over Fay is now gone, sitting to the south, providing westerly wind shear now over the storm. An ULL that has been sitting in the NW Caribbean has also caused Fay no end of grief, preventing convection from firing on Fay's west side for the last 2 days, as well as injecting dry air into her. Despite all this, conditions are conducive for moderate strengthening over the Florida Straights today, and with the NHC upping the winds to 60mph already, you can see that this process has already begun.

Ok where in the world will Fay go? You know something's fishy when we're 24 hours from landfall and we still don't have it pinned The reason is that the steering currents are very weird with this system, and it is still unclear how much the trough over the east coast will turn Fay to the north or NE today. Fay is currently moving NNW, and following the NHC track would put her near Fort Myers tomorrow morning. Any deviation would greatly change the landfall location, but I think any changes we see will be to the east, not the west. A shift east, even a small one, will make significant changes to the forecast. One, Fay would have less time over water to strengthen before landfall. Two, as some of the models are forecasting, Fay may move off the east coast of Florida and meander off the coast for a few days, potentially threatening the Carolinas, or even Florida again lol. The European and GFS have shown this for 2 runs in a row now, and to me that's a nasty pair of models to be agreeing on a steering pattern, so I would pay attention to them. I'm forecasting landfall SE of Naples, near that little "niche" in the coastline between Naples and the Everglades as a borderline Category 1 hurricane. Naples would be the furthest west this goes in my mind, but a landfall north of Naples does not seem likely to me right now. It is very possible that Fay could trek east as well and hit the Everglades or extreme South Florida, in which case Miami may get a heavier beating than they expect. Indeed TS winds extend out 105 miles, so Miami should be expecting a nasty day no matter where Fay goes.

So bottom line is a strong tropical storm or borderline hurricane is making landfall in south Florida in the next 24 hours. There is still potential for more people to be threatened by Fay after crossing Florida. I will spend more time contemplating Fay's future track after she's done with Florida, at least Florida landfall number 1 lol. Right now the focus is on the next 24 hours, but I don't think Fay will stop there and will continue to tease everybody. Please heed the warnings issued by the NHC and your local weather office, stay safe, be prepared.

We shall see what happens!

^Click for loop^

Fay forms

By: Levi32, 6:21 PM GMT on August 15, 2008

Update 8pm EST:

We FINALLY have Tropical Storm Fay, as the recon found west winds south of Hispaniola today, prompting the upgrade by the NHC. The storm looks amazing and continues to improve in organization and structure despite being over the Dominican Republic right now. Latest models have Fay moving over tons of land over the next 4 days, and intensity will be completely determined by how much land Fay has to cross. For the near-term, I expect Fay to pick either the northern or southern coasts of Hispaniola, and then hug that coast, but I don't expect a track straight across the island, because weak systems like this are extremely versatile and can jump their centers wherever they like near the water and deeper convection. Right now it is still unclear exactly what Fay wants to do over the next 24 hours, but these next 24 hours will probably determine where she goes afterwards. If she picks the north coast of Hispaniola, then she goes north of Cuba and east of Florida. If she picks southern coast of Hispaniola, she goes south of Cuba, crosses western Cuba, then hits either western Florida or the Florida Panhandle. If Fay goes between these and directly across Hispaniola, she will proceed across the length of Cuba and up the Florida Peninsula. It's as simple as that. Again there's no way to tell what the intensity will be like until we know what Fay will have to contend with land-wise, but what we can say with confidence is that Fay has lots of potential to rapidly intensify as soon as she gets any time over water. The pattern is near perfect, and she's a weak system which means she won't be as adversely affected by these islands as a major hurricane would be. Even 48 hours over water before landfall could deliver a serious hurricane to whoever Fay hits, so everybody from Mississippi eastward to the Carolinas should keep a very close eye on Fay over the next 5 days.

Previous Update:
As some have dubbed it, The Great Saga of 92L continues this morning. The recon hasn't found a closed LLC yet, although the dominant one is pretty close to closed, if not already. The circulation is just messed up with a couple weaker vortices trying to compete with the main one which makes the plane data confusing to read. However, there is indeed a main vortex low-pressure center which is currently over water between PR and the Dominican Republic, northeast of the DR coast. The first matter that deserves mentioning is that Hispaniola will get heavy rains from 92L, and we all know that any kind of tropical system over that island can result in a huge loss of life, so please keep them in your prayers. Hispaniola will have to deal with 92L for the next 24 hours.

Ok, I'm gonna do this backwards and discuss the track first, since it has so much to do with the intensity forecast. Alright, step 1, everyone is trying to find where exactly the LLC is. Honestly it's impossible to make a good track forecast without knowing where the storm is, wouldn't you agree? lol. A more southerly relocation of the center will result in a possible path through the islands and possibly the northern Caribbean. If the LLC is still where I think it is, the path will take it along the northern coast of the islands and into the Bahamas. A shortwave trough will be moving off the east coast in 3 days, inducing a weakness in the ridge over the Bahamas. This will turn 92L more towards the NW, through either the Bahamas or the eastern gulf. As I stated yesterday in another blog, I still believe this is an east coast/Florida problem, but the door to the GOM is still wide open. The ECMWF, GFDL, and HWRF models all take 92L up near the east coast of Florida and then eventually hitting South Carolina. The end game here will get very nasty as the shortwave trough won’t last that long, meaning the ridge will build back in very fast, probably slowing or even stalling 92L/Fay out just off the east coast. This is both good and bad, for the storm would probably upwell cool water and weaken, but at the same time enlarging its wind field. Bottom line here is there is still a huge amount of uncertainty, with lots of it due to the models not knowing exactly where the location of 92L’s center is at this point.

Alright, how strong will Fay get? Again this is very much dependent on the track. Obviously a track more over the mainland of Hispaniola and Cuba would very much weaken or border-line destroy the system. 92L would rebound extremely quickly after getting free of these islands, but probably would not be able to get as strong as it could if it takes a track near the coast of the islands. This track would probably keep 92L at TD/weak TS status (assuming it gets upgraded eventually) until it passes Hispaniola. Thereafter Fay should begin to strengthen despite proximity to Cuba, and then could really take off once it makes a turn north into the Bahamas and all that warm water. This is based on the fact that there is a well-developed anticyclone over the top of 92L right now, the structure is slowly improving, outflow expanding, and the whole system will continue to organize even while over land areas. This means that once it finally gets some breathing room, 92L will really take off in a hurry. The GFDL and HWRF continue to forecast a major hurricane off the east coast in 3-5 days. I'm assuming this will be the track for now, but if the LLC reorganizes further south we will have a whole new ball game in the Caribbean.

Very interesting system yet again, and there is still a lot of uncertainty, so everybody from the eastern gulf Coast to Cuba to Florida to Cape Hatteras should keep a close eye on this system.

We shall see what happens!

^Click for loop^

Fay is on the way

By: Levi32, 4:51 PM GMT on August 14, 2008

I haven't been able to blog lately because things have been really busy, but I plan to make time for this threatening storm over the next week.

Invest 92L has finally overcome all the dry air problems and developed a nice compact deep ball of convection which has sustained itself since last night. The circulation is closed, but is extremely hard to locate this morning. Low-cloud movements would suggest that it is somewhere near the western or NW edge of the big ball of convection, but I can't be certain. An anticyclone is situated directly above the big ball, and is causing outflow to expand in ALL quadrants equally, something we have not seen with any other storm so far this season. This setup is very conducive for strengthening, and I don't think anything is going to stop 92L now except land interaction. Due to the way things are set up, I believe the center will eventually get sucked under the ball of convection and get aligned with the mid-level vortex, which is when this system could really take off. Dry air is still around but shouldn't pose a problem now that it has been mixed out and the anticyclone is building over top of the system. Wind shear is low, again due to the anticyclone above the storm.

This is a classic example of what I have been talking about when a wave off Africa appears to fall apart and stay weak, but it does not die, rather it waits until it gets underneath the high and then develops on the other side under more favorable conditions. This is exactly the kind of threats that are the most dangerous. An early developing storm off Africa will usually recurve, but these sneaky ones that I talked about will hit the United States more often than not. Also although 92L took several days to get its act together, that whole time it was improving its structure, therefore it won't take much to get it to take off now that it has plenty of convection.

Ok so I'm sure it's apparent I think this is going to be Fay soon, but how strong will she get and where will she go? As I said there is really nothing to stop her except land. Most of the models take 92L very close to Hispaniola after passing just north of Puerto Rico. Proximity to Hispaniola could really disrupt this system, if not completely dismantle it. It is important to note though that even a weak TS passing near Hispaniola usually results in a huge loss of life due to the heavy rains, so this is not a good situation for them. Once passed Hispaniola, some models take 92L over Cuba too, which would really kill it, but then the game opens up in the GOM where we'll have to think about a whole new situation. The majority of the models don't do this, however, and instead take 92L close to Cuba but then turn it north off the east coast of Florida, which is when most of the models finally strengthen the storm. The GFDL keeps 92L a very weak TS until the Bahamas and then turns it into a minimal hurricane at the end of the run. The HWRF has a 930mb hurricane with the last 2 runs in the same position east of Florida. The ECMWF brings a monster storm east of Florida as well which stalls and eventually turns west into South Carolina. The end game with this system will be a huge headache as this storm could impact a large area, as possibly a major hurricane. Although this is still very far out, I think it is worth saying that the only thing that could weaken Fay off the SE coast is upwelling of cold water if she stalls too long before making landfall. Otherwise I think this could be one heck of a storm if it doesn't get completely torn apart by the Caribbean islands.

In summary, 92L is nice and compact and should become Fay today or tonight. Puerto Rico will feel the bulk of the storm tomorrow, as will Hispaniola shortly after. Depending on the exact track and proximity to land masses, 92L could strengthen quite rapidly in the Bahamas, posing a threat to the SE coast including Florida. All people of these land areas should keep a close eye on this system over the next week, as it will be a big headache to many.

We shall see what happens!

^Click for loop^

TS Edouardo heads for Texas

By: Levi32, 3:53 PM GMT on August 04, 2008

My apologies, been busy last couple days so haven't been able to post...

TS Edouard is now accelerating on a westward track towards the Texas coast. The system was struggling a lot yesterday due to dry air entrainment and northerly shear. The dry air is getting mixed out this morning as new convection fires near the COC. The shear is still there, but it is light at around 10kts. Until this morning the COC was completely exposed due to this shear, but now convection is trying to wrap around the center. The upper-level environment is improving, but it is not exactly ideal. An upper high to the NW of Edouard is severely inhibiting outflow on the west and north sides, and is the cause of the northerly wind shear. However, an ULL in the Caribbean is greatly enhancing Ed's outflow channel to the southeast, and for the moment is providing plenty of upper-level divergence. That means that enough air is getting pulled out of the top of Ed to allow more air to enter in the bottom without piling up, hence lowering the air pressure. I expect Ed to begin a steady strengthening phase today, but with only 30 hours left over water, it will be difficult for him to attain hurricane status. Systems of this nature have the ability to ramp up very quickly due to their small size, but since Edouard took so long to get his act together, I am forecasting his peak intensity to be 60kts(70mph).

Where's he going? That's pretty easy (phew!!)....for once. All the models are in good agreement on the upper high to the north of Edouard steering him to the west today, gradually turning WNW as he rounds the southern periphery of the high. I am in close agreement with the NHC track forecast, and I'm forecasting Edouard to make landfall at or just north of Galveston, Texas as a 60kt tropical storm, with the "cone of error" between Freeport, TX and midway between Galveston and Port Arthur. Please keep in mind that I am not an official meteorologist of any kind and you should listen to the NHC and your local weather office for any instructions. Residents of the Houston area should also prepare for hurricane conditions as Edouard will be near borderline hurricane strength at landfall.

We shall see what happens!

Edouard warnings/watches and forecast track:

Edouard radar loop:

Edouard visible satellite:

^Click for loop^

Edouard forecast model tracks:


Elsewhere in the Atlantic:

Our other 2 invests pretty much fizzled, and there's nothing else much to watch at the moment. There is another wave off Africa that may need to be monitored, and a couple more will be coming off in the next 2 weeks. Keep in mind this is still the downward phase of the MJO, so it's actually pretty impressive to have all this activity right now. Mid-late August things will really start to crank up and we'll hit the real deal this season. For now keep your eyes on the gulf, Caribbean, and western Atlantic for development. What about the eastern Atlantic?? ......nah...too many problems for the Cape Verde systems right now...but they will try to sneak under the high and develop once they pop out on the other side, so make sure to watch those too.

Tropical threat close to home........and more invests

By: Levi32, 6:45 PM GMT on August 02, 2008

See, I told you, who says downward MJO pulses can't have activity lol :). We have 3 areas of interest to watch in the Atlantic today. I'll start with the biggest threat close to our coastline.

91L is over the northern GOM south of Pensacola, Florida. This little system is currently composed of an upper-level vort max that split off the tail-end of a long-wave trough over the eastern seaboard. We call this a trough split, and when these vort maxes get into the GOM they can cause home-grown mischief. Right now there is only a small surface trough associated with this system, but a closed low could easily form soon due to southwesterly winds over the gulf and northeasterly winds over the northern gulf coast.

Indeed some of the models, specifically the GFS, are forecasting this to occur. The GFS forms a closed low today as it moves south away from the coast, and then turns to the west around the periphery of an upper high over the Great Plains, eventually hitting the Texas coast around the Houston/Galveston area in about 3 days. There is no need to panic, there isn't even a surface low yet with this system, but I do believe this is a real threat to develop as conditions are very conducive over the GOM right now. The feed-back cycle has already started with the main cluster of thunderstorms south of Pensacola, and I believe a surface low will form soon. The NHC has placed this area under orange (20-50% chance for development), so they are also keeping an eye on it. Exactly how far south this system gets before turning west will be critical in determining how much time the system will have over water to get its act together. People all along the north gulf coast should keep an eye on this system for possible development over the next couple days.

High-res visible loop of 91L

Radar loop of 91L:

91L model forecast tracks:



An area of low pressure out in the central Atlantic is slowly becoming better organized. The circulation was bare for quite a while as the system moved over cold SSTs, but new thunderstorms are starting to form as 99L moves back over warmer waters. This system has potential to develop over the next couple days while conditions remain fairly favorable. After that 99L will be encountering one of the infamous ULLs which will inflict wind shear over the system, which will likely halt any attempt at intensification. Nevertheless, this is a classic example of what I was talking about in my previous blog. Weaker systems off Africa will slip under the high, make it further west, and try to develop after they pop out on the other side. This is what 99L is trying to do, and as long as it has a well-defined circulation we should continue to watch it carefully. The models are in agreement with a continued due west track for a while, keeping 99L below 20n until around 60w. I won't even mention the possibility of any land areas being affected until we see some development of this system.

99L visible satellite imagery:

^Click for loop^

99L model forecast tracks:



Invest 90L is located SW of the Cape Verde Islands. This system consists of a cluster of thunderstorms which has persisted for the last 36 hours. There is no surface circulation yet, but there is a mid-level feature which is giving the system a nice appearance on satellite imagery. This system is down near 12n, and will take a more southerly track than 99L. This system probably has the better chance at development of the two, and should be watched carefully as it moves generally west over the next several days.

90L visible satellite imagery:

90L model forecast tracks:


There are no other areas of immediate interest in the Atlantic basin. Our next major MJO upward motion pulse is scheduled to arrive in a couple weeks, and that's when the real track race will begin. In the mean time, the Caribbean, western Atlantic, and GOM should be watched for activity as African waves slip across, and things like trough splits make home-grown mischief.

We shall see what happens!

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Tropical Tidbits from the Tundra

About Levi32

Masters student in tropical meteorology at FSU. Raised in Alaskan blizzards, but drawn toward tropical cyclones by their superior PGF.

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