CybrTeddy's tropical weather blog

Isaac organizing, TD10 develops - 8/22/12

By: CybrTeddy, 3:45 PM GMT on August 22, 2012

Good afternoon and welcome to my tropical weather update for Wednesday, August 22nd, 2012. We are now dealing with organizing Tropical Storm Isaac entering the Caribbean and Tropical Depression 10 which is very likely to become Tropical Storm Joyce sometime within the next 24 hours. I am very impressed to be up to our 10th tropical depression by August 22nd. What is more impressive is the fact that it is an El Nino year. I'd have been less impressed if all these where from like cut off lows off the US East Coast like they where last year, or non-tropical in general. But every storm this month that has developed has done so from a tropical wave off Africa. That's usually a good signal for an active season.

Figure 1. Current satellite image of the two cyclones.

Forecast for Isaac
Looks can be deceiving, and Isaac is certainly a prime example of what I would call just that. From satellite, if this where out in the middle of the Atlantic this would be approaching hurricane status, however it appears according to recon that pressures are at a high 1006mb, and winds are only 45mph. This is exactly, once again what happened with Hurricane Ernesto, and it feels like we're talking about Ernesto all over again like we where a few weeks ago.

Figure 2. My personal satellite interpretation of the current situation.

I believe this a combination of the fact that Isaac is moving at 21mph, and there is dry air penetrating Isaac to the north. However, Ernesto was a very small system when it entered the Caribbean with minimal spiral bandings, Isaac is massive with impressive spiral bandings, this will defiantly help fend off any dry air in the Caribbean like Ernesto had to deal with. Once we begin to see deep spiral banding on the north side, that will be our hint for strengthening. Another factor is that Isaac's Upper Level Anticyclone (ULAC) is misplaced and that is allowing for some shear to becoming in on the northeast side. Unlike Ernesto which had issues with spiral bandings on the more critical West side, this will seal off as Isaac enters the Caribbean and become less of an issue.

Figure 3. Current CIMSS wind shear analysis.

The track is a difficult issue, I will be honest with you I have little idea where it will go after Haiti. A lot of storms that exit Haiti tend to experience a 'bump' westward that causes a shift west that could very well increase the threat to Florida and the Gulf Coast. The NHC is thinking along the lines of the models that this will impact Haiti as a Category 1 hurricane and weaken, then strengthening as it heads towards Florida, strengthening back into a hurricane. It's not hard to image what would happen if Isaac got into the Gulf as a hurricane as shear is low and there is SST's and TCHP that haven't been touched by a cyclone in peak season for many years.

Figure 4. Current forecast track for Isaac.

Tropical Depression 10 likely to strengthen
Our next area of interest is organizing Tropical Depression 10 off the coast of Africa, continuing the string of tropical cyclones developing the last few weeks. TD10 is no threat to land but does bare watching over the next few days. I suspect hat this will become Joyce and perhaps even approach hurricane status as the NHC is predicting it might do towards the end of the run. A lot of this depends on how large Isaac gets and how much that will have an influence on track and intensity. Right now, it is unlikely TD10 will approach the Caribbean as Isaac did.

Figure 5. Current satellite image of TD10.


Gordon hits the Azores, 94L, 95L, and 96L all worth watching - 8/20/12

By: CybrTeddy, 3:28 PM GMT on August 20, 2012

Good morning everyone and welcome to my tropical weather update for Monday, August 20th, 2012. The tropics are responding to the time of year with having 3 different systems to watch out in the Atlantic not including, Hurricane Gordon, which managed to make a rather unexpected run at Category 3 status, peaking at 110mph, just shy of becoming a major hurricane as it approached the Azores. Gordon is similar, in many ways to it's predecessor - Hurricane Gordon in 2006. That system also brought tropical storm force winds to the Azores. However the Azores is used to these kind of systems in the winter bringing howling rains and is not a real threat for serious damage as it is now down to tropical storm status.

Figure 1. Hurricane Gordon at peak intensity.

Disturbance Invest 94L a threat to develop into Isaac
Yet another confusing and hard to understand situation is developing in the Atlantic. In a seemingly repeat of the events that spawned Ernesto, we are now facing a similar situation, a disorganized tropical wave with so-so model support and a lot of dry air. That is Invest 94L currently located out in the tropical Atlantic. However, I do not think 94L will in the long run become another Hurricane Ernesto, rather I think there's a chance that it could be a threat to islands and even the United States. The GFS and European models have all backed off on an intense system in the short term, this is thanks to the amount of forward speed 94L is having to deal with. Buoy data shows that 94L indeed has a closed circulation. The NHC is giving 94L an 80% of becoming a tropical cyclone in the next 48 hours.

Figure 2. Latest satellite image of Invest 94L.

I believe that 94L will probably become Tropical Storm Isaac sometime in the next 72 hours, and that the European model is wrong in suggesting that this won't even become a tropical cyclone. This is one of those times where you simply can't look at the models for your predictions. It's mid to late August, there's a tropical wave out in the Atlantic with low shear and working out dry air out of its system. That alone is good enough reason to believe it has a chance to develop.

Figure 3. Latest intensity model predictions.

The GFS is saying that 94L will develop but will not become a major threat until it reaches the Gulf of Mexico. I will be honest, I believe the HWRF/CMC/UKMET seem to have the better handle with this system in terms of short term intensification. The pattern in place does not support 94L becoming a Caribbean cruiser as there is a weakness at ~60W, so I do not believe that it will track all the way to the Yucatan. Eventually, I believe it will head north some.

Figure 4. Latest 'Spaghetti' model track for Invest 94L.

Invest 95L a threat to develop in the Gulf of Mexico
Associated with the remnant area of low pressure from Helene, which briefly developed between blog posts in the Gulf of Mexico and quickly moved inland, 95L has developed in the Gulf of Mexico. Little movement is expected, though I expect that the general path will be NE as there is a weak trough draped out over the Gulf that is helping to give this system some 'juice' so to speak. 95L has little to no model support with the exception of some of the FIM and GFS ensemble members. The NHC is giving 95L a 30% chance of developing into a tropical cyclone over the next 48 hours. Heavy rain should be expected over the Gulf and Texas during that timeframe.

Figure 5. Latest satellite image of Invest 95L.

Invest 96L could slowly develop over the next few days.
Our final area of interest is Invest 96L currently located south of the Cape Verde islands. Satellite reveals a disorganized wave but with less dry air than what 94L had to deal with. Model support is very limited about this system, and it appears this system will probably be similar to the invest that spawned TD7 - eventually Helene - which also had no model support. I do not expect major development in the next 24-48 hours. The National Hurricane Center is currently giving this low a 20% chance of development.

Figure 6. Current satellite image of Invest 96L.


Gordon forms - moving away from landing, Cape Verde development probable - 8/16/12

By: CybrTeddy, 1:42 PM GMT on August 16, 2012

Good morning and welcome to my tropical weather update for Thursday, August 16th, 2012. The African wave mentioned in my previous update moved off of Africa and is now Tropical Storm Gordon - the 7th named storm of the season. I would like to point out that the fact we are on Gordon in mid-August is probably a signal that this hurricane season will be at least slightly-above average. True, in the case of Alberto, Beryl and Chris, one could argue the fact that three of those where non-tropical developments. However, this is the 3rd named storm to develop just in the past two weeks and it appears this active period isn't likely to end soon. We are in that time of season where things naturally begin to pick up even in the slowest of years.

Figure 1. Satellite image of Tropical Storm Gordon.

Gordon should continue to intensify and could become a hurricane sometime soon. Latest microwave images show that Gordon has already developed a fully mature eyewall and will likely strengthen throughout the day. Gordon is no threat to land fortunately with the exception of the Azores. In an interesting turn of fate, the last tropical cyclone to directly impact the Azores was Hurricane Gordon of 2006, which became a major hurricane.

Figure 2. Current forecast track for Tropical Storm Gordon.

Watching Africa for tropical development
The next area of interest to watch out for is the possibility of our first major Cape Verde hurricane. The GFS, ECMWF, and CMC all indicate that a tropical wave will emerge sometime this week and gradually develop into a tropical storm. This seems a fair solution, we're in that time of year that tropical cyclones generally do develop off Africa in even the slowest of years and become major hurricanes. I suspect that we could see Helene very soon.

Figure 3. Current European (ECMWF) model run out to 120 hours.

It is too early to really begin to speculate on track, however it appears that the North Atlantic Oscillation (NAO) will be going negative over the next few days. This will in turn cause the A/B high to drop further south but will also cause it to weaken and allow for troughs to easily erode it and allow storms to move out to sea. This is the case usually for Cape Verde hurricanes regardless of the NAO, as a positive NAO would also allow for a system to move out to sea.

Figure 4. Latest ECMWF NAO forecast.

Paying attention to the Gulf of Mexico for development
There is a possibility that part of the remnants of Tropical Depression 7 could combine with a frontal low and develop into an entirely new cyclone. The NHC recognizes this fact and gives the remnants of TD7 a 10% chance of this happening. The models are very so-so on this right now with the ECMWF perhaps being the most aggressive. Time will indeed tell what happens.


Ernesto moves inland, Tropical Depression 7 and African waves to watch - 8/9/12

By: CybrTeddy, 9:00 PM GMT on August 09, 2012

Good afternoon everyone and welcome to my tropical weather update for Thursday, August 9th, 2012. We have two areas to talk about, but first I'd like to make a final mention of Hurricane Ernesto, which made landfall as a 85mph Hurricane in the Yucatan Tuesday night. Ernesto was more than likely a Category 2 hurricane at landfall, satellite showed continued intensification with a steady building eyewall and a well maintained CDO (Central Dense Overcast) several observations made by storm chasers revealed the pressure at landfall was around 975mb and winds where 90-100mph. This is consistent to what we saw as Ernesto moved into land and could very well be upgraded post-season as discussed in the NHC discussion. The only reason we didn't get a good handle on the intensity was due to a malfunction in the recon that caused the flight to be grounded until the next day.

Figure 1. A 975mb reading recorded by iCyclone chasers in Hurricane Ernesto.

Tropical Depression 7 forms in the Tropical Atlantic
The tropics have again lightened up with another system. Invest 92L became better organized the last day or so and managed to be declared a Tropical Depression just at 5pm. TD7 is again a rather tricky intensity and track forecast. The GFS model reveals that shear will be high as the system nears the islands and refuses to develop it into a system, this is also true with the ECMWF. The CMC and NOGAPS seem to develop this into a tropical cyclone, but are notoriously not as accurate as the GFS and ECMWF. Worth noting though that the ECMWF failed to develop Ernesto, Florence, and TD7 all in a row - this is why looking at models can only go so far and you really have to look at the situation at hand.

Figure 2. Satellite image of Tropical Depression 7.

Thanks to Ernesto, shear is generally high in the Western Caribbean however this will dissipate as Ernesto moves inland into Mexico. Should TD7 not open up into a wave due to the combination of high shear and very dry Saharan Air, it could have a shot at intensification once it reaches around Jamaica's longitude. This situation will probably be similar to Ernesto, as the trade winds in the Eastern Caribbean will act to cause TD7, or Gordon by that time, to become disorganized on the surface even though the satellite will probably be more impressive. Only gradual intensification is expected until the system reaches the Western Caribbean next week.

Figure 3. GFS 850-200mb shear forecast by 24 hours.

African wave to watch for development
Another area to watch for development is off the coast of Africa. The GFS has been consistently developing this into a tropical cyclone as it moves off the coast, with the exception of the 18z - 06z runs last night which did not develop the system, but was picked up again by the 12z. This system should it intensify quickly would probably be drawn more northward that Ernesto and TD7 are. We have several days to watch this system, the NHC currently gives this a 20% chance of developing in the next 48 hours and I would place my odds at 30%, due to an abundance of dry air.

Figure 4. Satellite image of the African Wave.

I will admit, I am impressed with the pace of activity we have been having in August. We are facing the possibility of having Tropical Storm Gordon tomorrow, well ahead of schedule. Indeed, the 2009 Atlantic Hurricane season didn't get 'Grace' until October, and 2006 didn't get its Gordon until early September. This has caused Colorado State University and Tropical Storm Risk to raise their August predictions to both 14 named. The August predictions are generally more accurate of the predictions and are the last.


SPECIAL UPDATE Hurricane Ernesto - 8/7/12

By: CybrTeddy, 6:16 PM GMT on August 07, 2012

Good afternoon and welcome to my special tropical weather outlook for Tuesday, August 7th, 2012. I haven't posted on Ernesto much simply because there has not been much change with the storm until now. Ernesto failed to be influenced by the weakness to it's north and is now poised to make landfall in the Yucatan as a Hurricane. Hurricane Hunters discovered in the most recent recon that Ernesto has become a 80mph Category 1 hurricane, the second of the season as it churns westward towards landfall tonight or tomorrow morning.

figure 1. Latest satellite image of Hurricane Ernesto

Forecast for Hurricane Ernesto

Ernesto won't probably strengthen much beyond Category 1 strength as it's running out of time for rapid development, but I could see it becoming a 90mph hurricane just as it crosses the coast. Gradual organization is expected as the system exits the Yucatan and could regain Hurricane status. The Bay of Campeche is famous for causing storms to quickly intensify, this is due to the geographical shape of the coastline that acts to accelerate the winds in a cyclone, causing them to intensify. Recent examples are Hurricane Lorenzo in 2007, and Hurricanes Alex and Karl in 2010. All of these systems managed to intensify into potent storms before landfall. It all depends on how much time Ernesto gets over the Bay of Campeche for strengthening to really get going. In the end, I could see Ernesto at least regaining the strength it has now and perhaps even stronger.

Figure 2. Latest forecast track for Ernesto.

Florence no threat to re-develop into a cyclone
Wanted to make a passing mention that in my break of posting we did get Tropical Storm Florence, the 6th named storm of the season. Florence managed to intensify into a 60mph Tropical Storm becoming the first Cape Verde system of the season before dying due to the dry Saharan Air. Dry air and shear should keep Florence in check and regeneration is unlikely.

Invest 92L no threat to develop
Another disturbance, Invest 92L has also developed just south and west of the Cape Verde islands. The computer models do not develop 92L, but the intensity models are rather over-enthusiastic about the systems chances. Dry air will probably keep this system in check before development can occur, at most becoming a brief Tropical Depression before dissipating in about 3 days.

Figure 3. Invest 92L out in the Eastern Atlantic.

Watching for another wave to emerge later this week
Our next area of interest to watch for future development will be once again off the African coast as the GFS has been very consistent the last few days with developing a classic Cape Verde hurricane later this week. The other models, with the exception of the NOGAPS, are unenthusiastic about this but I do believe there is a good chance development may happen. Unfortuantly, this wave seems unlikely to recurve straight away and *could* pose a threat downstream. I will not guarantee this as it's all about timing, but the GFS has been showing in the long range this getting close to the United States. We'll see what happens. Focus though on the initial development before actually seeing this come towards the United States or any body.

Figure 4. Latest GFS model run 84 hours out showing a possible Tropical Storm over the Cape Verde islands.


Tropical Storm Ernesto, Invest 90L, Invest 91L all worth watching - 8/3/12

By: CybrTeddy, 4:56 PM GMT on August 03, 2012

Good afternoon and welcome to my tropical weather update for Friday, August 3rd, 2012. The tropics are awake that's for sure, with three areas to watch. The first is Tropical Storm Ernesto, located at 13.7°N 62.3°W. Maximum sustained winds remain at a level 50mph . Satellite reveals a decent structure to Ernesto but lacking in convection. This is likely to the fact that Ernesto is entering the ''dead zone'' so to speak where convergence in the area is lackluster. The trade winds though have relaxed over the system and it appears intensification is forth coming in the next few days.

Figure 1. Current satellite image of Tropical Storm Ernesto.

The forecast for Ernesto.

Ernesto is currently trucking west at 20mph, this is a defiant con against real intensification. Such a quick forward motion often tends to not allow storms to use full advantage of the TCHP and SST's currently situated under the system. You have the other fact that Ernesto is entering a deadzone, an area that the Eastern Caribbean is famous for having. Basically the trade winds are causing all the real convergence to be pulled away from Ernesto and pile up in the Western Caribbean. This is a double edged sword, while this will cause Ernesto to only have steady intensification if any at all for the next few days that means that when Ernesto arrives in the very deep TCHP there will be little to stop it from intensifying.

Figure 2. Current TCHP image of the Western Caribbean.

The NHC forecast reflects this fact. They are showing Ernesto maintaining strength until it reaches south of Jamaica. By then it will be entering the Western Caribbean and could become a potent hurricane if the conditions remain so. The models are very so-so on Ernesto. I believe though they are struggling to handle the system thanks to it's small size. A 1002mb 50mph Tropical Storm is going to have a different tug on the steering currents than a 1009mb Tropical wave would as the GFS has been showing and has been burring it into Central America with the European model. I discount these scenarios due to poor initialization. I believe that the system will continue a W-WNW track and continue to be disorganized and then intensify. After that, it appears it is possible that a weakness could develop in the Western Caribbean that will cause to pick up Ernesto or head it WNW-NW, perhaps just scrapping the Yucatan.

Figure 3. Current 'spaghetti' model chart for Tropical Storm Ernesto.

Watching Invest 90L for development
Our second area to watch is off the Cape Verde islands and off the Florida coast. A very healthy looking tropical wave has emerged off the African coast and is being given a 30% chance of development in the next 48 hours, and is now being called 90L. Satellite shows an organizing tropical wave with a fair chance at becoming a named storm. Model support for this is very lackluster, none of the major global models are showing development but it is an area to watch. It is too early to really sniff out a possible track but due to the possibility that I mentioned that a trough might be influencing Ernesto in the future more NW it is possible this system will be pushed away from land.

Figure 4. Current satellite image of Invest 90L.

Invest 91L not a real threat for development
The final area of interest is a disorganized tropical wave just situated to the east of Florida that is producing scattered showers and thunderstorm activity. This wave is encountering heavy shear, but if the shear begins to let up there is a chance that something could happen. Without surprise, the models aren't enthusiastic about developing this either. However, if develop though does begin with this system it is possible that it could influence Ernesto towards land.

Figure 5. Current satellite image of 91L.


Tropical Disturbance 99L a threat to develop - 8/1/12

By: CybrTeddy, 2:32 PM GMT on August 01, 2012

Good morning and welcome to my tropical weather update for Wednesday, August 1st, 2012. The tropics is finally producing something interesting with Invest 99L located in the Central Atlantic. Satellite shows a fairly organized disturbance, with spiral banding and outflow beginning to become more prominent in the last few hours. Based on this, the National Hurricane Center has upped the chances for development into 60% in the next 48hrs. A surface circulation is finally starting to become per satellite loops, which appears to be located in the Northwest Quadrant of the convection.

(figure 1. Latest satellite image of Invest 99L)

Forecast for 99L
99L has finally it appears managed to break away from the ITCZ that was connecting it for the last few days and is beginning to sustain it's own convection. However, it needs to stop heading north too much as it will run into a ban of 20-30kt shear that will blast it apart. I don't think that will happen, instead I think that it will manage to actually get ventilated by this as it begins to take a more west course.

(figure 2. Latest shear analysis)

The models have been pretty unreliable with developing this into anything, most of them either started out the system wrong or just flat out refuse to develop it into a Tropical Depression even. The CMC, GFS, and HWRF are the only models wanting to show some sort of development. That being said, the SHIPS shows fairly high humidity and low windshear for the next few days and brings the system to 52 kts in 72 hours. Saying where this system is going to go is fairly simple I believe. Most of the models are saying that this will get into the Caribbean and I think it will too. However it appears the situation has changed with the shear, and there is a better chance for survival if it can get into the Caribbean that there was before. The HWRF and GFS are showing that once it can get past that area of high shear in the Caribbean intensification will occur in the Western Caribbean.

(figure 3. Latest spaghetti plot for Invest 99L)

Based on all this, I believe 99L has a 70% chance of becoming a Tropical Depression in the next 48 hours. I do not believe 99L will become a major system and could very well die over the Eastern Caribbean thanks to high windshear. I will be updating this blog if something drastic occurs later today or tomorrow.

UPDATE 5:30pm EDT.
Invest 99L has become Tropical Depression 5. No change in forecast is necessary, however as of the 5pm update the NHC is predicting a Category 1 hurricane in the Caribbean.


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