TD 2 nearly dead; African disturbance 90L gathering strength

By: Dr. Jeff Masters , 2:38 PM GMT on August 13, 2009

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Tropical Depression Two is near death, but is still worth watching. The dry, Saharan air to the north and west of the depression, combined with moderately high levels of wind shear of 15 - 20 knots, have almost completely destroyed all of TD 2's heavy thunderstorms. Satellite loops of the storm show a well-formed circulation, but almost no heavy thunderstorm activity.

Wind shear over TD 2 is expected to remain in the modereate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C three days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to to TD 2's north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that TD 2 will not be able to intensify quickly, and some of the models indicate the TD 2 may get destroyed in the next day or two. However, several models still predict TD 2 will become a tropical storm. The HWRF model predicts TD 2 will become a hurricane five days from now, but this seems unlikely given the dry air and relatively high wind shear affecting the storm.


Figure 1. Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

African tropical wave 90L
A strong tropical wave with a large circulation and plenty of heavy thunderstorm activity is a few hundred miles south of the Cape Verdes Islands, off the coast of Africa. NHC dubbed this disturbance 90L this morning. This morning's QuikSCAT pass shows that 90L has a very large circulation, and top winds of about 30 mph. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are in two major bands, to the north and to the south of the center. There is no heavy thunderstorm activity near the center yet, and this would have to happen before 90L can be named Tropical Depression Three. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not be affected by dry air and dust as much as Tropical Depression Two has been. Wind shear is about 20 knots over 90L, and is forecast to remain in the moderate range, 10 - 20 knots, over the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days, which are high enough above the 26°C threshold for tropical cyclone formation to allow some slow development to occur. The GFS and ECMWF models continue to predict the development of this wave, though they are now less aggressive about intensifying it than they were in earlier runs. The consensus among the reliable HWRF, GFDL, GFS, and ECMWF models is to bring 90L to point near or just north of the northernmost Lesser Antilles Islands 6 - 8 days from now. The storm could be at hurricane strength by then, as forecast by the SHIPS intensity model.

I'll have an update Friday morning.

Jeff Masters

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Quoting gaweatherboi:
Ive asked before but does anyone see Ex TD2 or 90L heading towards GA or the carolinas?


Probably not.
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Quoting gaweatherboi:
Ive asked before but does anyone see Ex TD2 or 90L heading towards GA or the carolinas?

Too early gaweatherboi.. TD2 would be lucky to become a TD again at this point.. TD 3 (90L) is definitely the one to watch, and at this point it's something to just keep in the back of your mind and watch the news for. Not something to preoccupy you and worry about.
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3035. jipmg
Very impressive convective activity around 90L.. we might end up with ana sooner than expected..

As for TD 12 it seems its moved into a more conductive environment for some slow tropical development, based on the latest satellite loops TD 2 isn't in such a hostile environment when compared to yesterday
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Ive asked before but does anyone see Ex TD2 or 90L heading towards GA or the carolinas?
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90L CIMSS Satellite Image

http://cimss.ssec.wisc.edu/tropic2/real-time/storm.frame.php?&basin=atlantic&sname=90L&zoom=4&img=4 &vars=11101000000000000000000&loop=0&llval=
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90L is looking mighty impressive, with beautiful outflow in 3 Quadrants. Depending on the depth of the circulation, I'd say this is the most organized it has been thus far in its life, and it could very well be named TD 3 in just about an hour.
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Local NWS forecast discussion (New Orleans) has mentioned wave north of Hispaniola may
bring heavy rains as early as Sunday night to
Gulf Coast. TD #2 may regenerate, but 90L looks like the one to watch.
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3029. GetReal











It does appear that TD #2 has returned from the sea of the dead, and now finds itself it a slightly better surrounding environment....

TD #2 and 90L seem to be far enough apart to allow development of both systems... Even though 90L dwarfs Td #2 in coverage area.
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Lol hey Stormtop hows your Gulf disturbance doing?
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Quoting KerryInNOLA:
This is the first time in my memory where there has been so much speculation about where a wave near Africa will strike the US. Anyone remember similiar situation. Are we worshiping the MODELS too much?


It's because this is the strongest model consensus all year.
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TD2 still isn't dead...

Methinks it is.. the spawn of Karen.
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Convection firing over ex-td2
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ex td 2 looks to be making a come back moving faster also wonder if high is beginning to build in faster above it. At any rate this maybe know as the vampire storm as it only comes out at night.
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Patience is a Virtue
Patience is a Virtue
Patience is a Virtue

I have been watching so many model runs today, and reading/lurking on the WU Blog whenever I have a chance. After looking and listening to both, my conclusion is still the same as it was before. Models are just that, models!! Forcasters, are just that, forcasters. Some forcasters may have better reputations than others, but the bottom line is, no DATA IS CONCRETE OR ETCHED IN STONE WHEN SYSTEMS ARE THIS FAR OUT & have NOT EVEN been classified as A TROPICAL SYSTEM YET.
I played golf today in South Forida Today. 94 degrees, and looked out to my east over the Atlantic. What may come from there is perplexing, but all I did realize is, its not what we say in here in this blog, and all the analysis etc, etc. It is all but what is meant to be...
No doomsday forcast should hither anyone from just enjoying life for what it is, but on the other side of that coin, do not take life for granted.

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3021. centex
Quoting KerryInNOLA:
Still is possible that it does not develop into hurricane .This is an El Nino year.
agree current year must have real change before we asume next wave will develope. I only care about now and forecast in 24-48 hours.If I here 24/48 hour forecast wrong I only think they have no clue.
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3020. 7544
now in dmax new pics

Link
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Quoting KerryInNOLA:
Still is possible that it does not develop into hurricane .This is an El Nino year.


This El Nino is still in its formative stages. It will not have a significant effect on Atlantic hurricane activity until the lag period typically associated with ENSO events ends.
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Quoting KerryInNOLA:
Still is possible that it does not develop into hurricane .This is an El Nino year.


Did that stop Andrew from becoming a hurricane, nevertheless a category 5?
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I've learned over the years that you have to be ready for anything...i remember going to bed thinking a weak TS was going to hit Se Tx and i woke up and had a Hurricane Humberto at my doorstep and the scary part is they said it was strengthening when it hit land think if it had a few more hours over water the coast could have had a cat 2 hurricane that nobody was ready for or even knew about
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It's so far out there are many possibilities... Will take a bit of time to see which pan out.
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3013. 7544
after katrina if any cat 5 or higher was a threat will they give more than jsut a 3 day warning alert to get peeps moving will it be like 5 days instaed dif than a cat 1 or 2 was just thinking about this as this is might be in progress
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For all we know the storm could recurve up the state of Florida which is common, and it wouldn't even make it in the GOM. Remember a trough is supposed to be in the area to bring it north.
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Quoting louisianaboy444:
Don't get me wrong the eastern seaboard is still under the gun but as for now the models are showing consistency with bringing this storm somewhere near florida and into the gulf...the 00Z Gfs has it hitting near New Orleans and the CMC has it hitting the florida pennisula just north of Miami and crossing into the gulf...This could change though but as of now that is what i'm thinking


This WILL change, count on it. The Euro takes it out to sea. Anywhere from Bermuda to New Orleans is at risk.
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3009. centex
Models suck, not meant for public consumption. If they had cones maybe public would understand. They are really bad after 3 days, worse if looking at wave. Ignore the models at this point, anyone who bases 5-10 day forecast on them is not valid, being nice.
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IMO i will stick my neck out and say that i think ex td2 could be trouble also as it gets closer to the gulf...
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Quoting louisianaboy444:
Its looking more and more like a gulf storm...maybe even a double hit...Florida then the North-Central or Western Gulf


Yeah, maybe, but before we start talking about a GOM hit, the islands need to be the top priority, then Florida. The GOM has nothing to worry about now; too many things would have to come in place for it to make it there, that's why I think it's unlikely.

Everyone just be prepared.
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3006. sky1989
Quoting KoritheMan:
Though I would like to add that what louisianaboy said is not impossible. It has happened before, and it will happen again. The last time we had a storm cross the Florida Peninsula and go into the Gulf and make landfall as a major hurricane was Andrew in 1992.

I'm not one for long-range forecasts though, but the forecast steering pattern definitely bears watching.


Don't forget Katrina-It hit Miami, Florida as a Category 1 and crossed into the Gulf, and we know what happened after that.
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Quoting philliesrock:
Talk about an extreme outlier...0z Euro even goes east of Bermuda, through 204 hours.


The ECMWF may well be a very reliable model, but reliable or not, when there is an outlier in a tightly clustered ensemble, it's best to ignore the outlier.
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Guillermo is developing a rather nice CDO, banding is improving, and anticyclonic outflow is quite well-defined in the northwestern quadrant of the circulation.
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Talk about an extreme outlier...0z Euro even goes east of Bermuda, through 204 hours.
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Don't get me wrong the eastern seaboard is still under the gun but as for now the models are showing consistency with bringing this storm somewhere near florida and into the gulf...the 00Z Gfs has it hitting near New Orleans and the CMC has it hitting the florida pennisula just north of Miami and crossing into the gulf...This could change though but as of now that is what i'm thinking
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Quoting 7544:


didnt katrina cross fla and into the gulf ?


Oh yeah, I forgot about her for some reason. >_>
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Quoting druseljic:


I'm sure it will, they always do...that's why I was picking... :-)


Ivan was forecast to strike the Bahamas, then the Florida Peninsula, then finally the central Gulf. Trust me, if the Gulf Coast has to worry about this, we won't know until well over a week out.
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2999. 7544
Quoting KoritheMan:
Though I would like to add that what louisianaboy said is not impossible. It has happened before, and it will happen again. The last time we had a storm cross the Florida Peninsula and go into the Gulf and make landfall as a major hurricane was Andrew in 1992.

I'm not one for long-range forecasts though, but the forecast steering pattern definitely bears watching.


didnt katrina cross fla and into the gulf ?
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Quoting KoritheMan:


Calm down, this is well over a week out from the Gulf. I imagine the track will change a dozen times before all is said and done.


I'm sure it will, they always do...that's why I was picking... :-)
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Quoting FloridaTigers:


Are you surprised?


I was hoping that he had changed after going through Wilma. Apparently not.
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Though I would like to add that what louisianaboy said is not impossible. It has happened before, and it will happen again. The last time we had a storm cross the Florida Peninsula and go into the Gulf and make landfall as a major hurricane was Andrew in 1992.

I'm not one for long-range forecasts though, but the forecast steering pattern definitely bears watching.
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Quoting KoritheMan:


Don't tell me you're actually hoping that 90L doesn't recurve...


Are you surprised?
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2993. centex
Quoting louisianaboy444:
Its looking more and more like a gulf storm...maybe even a double hit...Florida then the North-Central or Western Gulf
At least giving my 1000 mile range. What we need is 24-48 hour projections based on new data.
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Quoting druseljic:


No....Shhh...


Calm down, this is well over a week out from the Gulf. I imagine the track will change a dozen times before all is said and done.
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Quoting louisianaboy444:
Its looking more and more like a gulf storm...maybe even a double hit...Florida then the North-Central or Western Gulf


No....Shhh...
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Its looking more and more like a gulf storm...maybe even a double hit...Florida then the North-Central or Western Gulf
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Quoting WeatherStudent:


We'll see about that. That model is currently the odd one out, out of all of them right now. Og well, hopefully he'll jump onabord with the otehr ones soon enough I'd imagine :)


Don't tell me you're actually hoping that 90L doesn't recurve...
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.