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 TampaSpin:
This is a big time OUCHY!

How many hours out is that Tampa? And Good morning
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12Z.

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Some -70 cloudtops around the remenant low formerly known as TD02.

NOW can I call it impressive?!
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Quoting TampaSpin:


OLd TD2 is under less Shear.....comeback is coming probably today.....i still think it will enter the Caribbean.

yep I see it already making a comeback and I think it will enter the caribbean too
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Quoting Skyepony:


I've been eyeing it since 50W, surface obs since yesterday, since it was in an area where we could get alot of them. Mid level circulation has improved alot over night. That west wind is still there, a NW one has also popped up since, S of cuba to the SW of the new convection. I need a ship just N of the East end of Cuba. Suprised about the West coast of FL totally discounting this. One model had it as a TS hitting Tampa in 48hrs.


I guess we will watch it along with the others , thanks!
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Member Since: March 19, 2009 Posts: 0 Comments: 1421
3430. szqrn1
TWC this morning showed the model run bringing 90 up to central Gulf Coast. I looked at the FSU site that shows the models but it does not take it out that far in time.

Need a good link to the model run that they had on...and all the models... Thanks
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3429. lilElla
Good Morning All!

#3375
I'm another lurker and isn't that fasinating, it has been spinning across the state all night. Is it a closed low? And 1-2" rain/hr!

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This is a big time OUCHY!

Member Since: September 2, 2007 Posts: 178 Comments: 20443
Quoting keywestbrat:

Hi how ya doing? I have the same Bday you do.



Well that is great!
Alot of folks call Aug 19th their birthday.
I think it has something to do with "holiday parties" in Late November and December !

So we will watch the storms next Wednesday together? LOL
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Good morning Orca, Hope your morning is starting off sunny. That may change though
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Quoting jasoniscoolman10:
WOW..


OLd TD2 is under less Shear.....comeback is coming probably today.....i still think it will enter the Caribbean.
Member Since: September 2, 2007 Posts: 178 Comments: 20443
Quoting reedzone:
The EURO is the only model that takes it out to sea, and before passing Bermuda.. This is not really possible because the ridge in reality is strong enough to keep 90L "Ana" to the south and can't recurve until it gets to the end of that high and encounters a trough which will either be
A. Off the East Coast and steers the storm away from the USA but WEST of Bermuda
B. Just on the East Coast and steers the storm up the coastline to New England
C. Catches the trough late and steers into Florida then recurves
D. Misses the trough all together (GFS) and heads into the GOM.


Actually the trough is not expected to become as amplified as in previous runs. The Bermuda High actually rebuilds back to the west in the 0 Z and 6 Z GFS. This is now the 3rd GFS run ina row that has trended south. Once reconnaisance can get in there and can get some real time data into the models, we still need to be very careful as not to take the models too seriously yet.
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If we see this continue then we may see 02L again and hopefully Ana so I dont have to pay for a gender change with 90L.
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Member Since: September 23, 2005 Posts: 14 Comments: 11222
Blog Update
Reflector site for those at work, which includes Weather456, daily update.


TD2

90L

AOI
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For 90L, I'd be keeping an eye on the Dvoraks as one of the possible barometres. If it gets bumped to 2.0, I'd expect an upgrade either the next time of an advisory, or the one after.

Right now is 1.5, so it's around that. TDs can be upgraded on 1.5, but don't think it'll happen in this case. The next one will be around 1800UTC, or 2pm EDT. That should be interesting.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
The EURO is the only model that takes it out to sea, and before passing Bermuda.. This is not really possible because the ridge in reality is strong enough to keep 90L "Ana" to the south and can't recurve until it gets to the end of that high and encounters a trough which will either be
A. Off the East Coast and steers the storm away from the USA but WEST of Bermuda
B. Just on the East Coast and steers the storm up the coastline to New England
C. Catches the trough late and steers into Florida then recurves
D. Misses the trough all together (GFS) and heads into the GOM.
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3415. eddye
some people on storm 2k saying oh shear affecting 90 l and i dont belive them
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Quoting P451:


Definitely organized, expect a renumber before 2:00 PM EST today, imho.
I can't find the "unfavorable conditions" in the Gomex that NOAA refers too? Any help?
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Look at the MJO forecast Map......this is trouble big time.......Not a good time of the Tropcial Season to have that kind of uplift of Moisture invading the Tropical Regions.

Member Since: September 2, 2007 Posts: 178 Comments: 20443
Thanks StormW
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think befor you post


right
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Keep watching 90L. Looks like things could get a little interesting. Most of the models are putting it uncomfortably close to the Carribean.
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3402. ackee 12:59 PM GMT on August 14, 2009
most of models are in agreement we may have ANA I think she TAKEs A TRACK smilar to GEORGES1998


geez...talk about a flooder of a storm "Georges"...don't need another in my backyard...
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Quoting Skyepony:


I've been eyeing it since 50W, surface obs since yesterday, since it was in an area where we could get alot of them. Mid level circulation has improved alot over night. That west wind is still there, a NW one has also popped up since, S of cuba to the SW of the new convection. I need a ship just N of the East end of Cuba. Suprised about the West coast of FL totally discounting this. One model had it as a TS hitting Tampa in 48hrs.


Look at the area off of Tampa right now... Huge area of rain. I wonder if it will make it onshore.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
thanks stormw....maybe not the synopsis we are looking for lol...but very good inforamtion as always...
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3402. ackee
most of models are in agreement we may have ANA I think she TAKEs A TRACK smilar to GEORGES1998
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Quoting Cotillion:


That's interesting, good spot. Do NHC really make forecasts for invests? I've not seen any lines for OFCI on them before, usually just the BAMM models.


Normally they do not, but it appears they did. Data from the model run files:

AL 90 2009081406 03 OFCL 0 117N 250W 25 0 DB
AL 90 2009081406 03 OFCL 12 118N 271W 25 0
AL 90 2009081406 03 OFCL 24 119N 293W 25 0
AL 90 2009081406 03 OFCL 36 120N 320W 25 0
AL 90 2009081406 03 OFCL 48 123N 351W 25 0
AL 90 2009081406 03 OFCL 72 135N 415W 25 0
AL 90 2009081406 03 OFCL 96 150N 480W 25 0
AL 90 2009081406 03 OFCL 120 170N 550W 25 0



AL 90 2009081412 03 OFCI 0 121N 265W 25
AL 90 2009081412 03 OFCI 12 122N 287W 25
AL 90 2009081412 03 OFCI 24 123N 311W 25
AL 90 2009081412 03 OFCI 36 125N 340W 25
AL 90 2009081412 03 OFCI 48 130N 372W 25
AL 90 2009081412 03 OFCI 60 136N 403W 25
AL 90 2009081412 03 OFCI 72 142N 436W 25
AL 90 2009081412 03 OFCI 84 150N 468W 25
AL 90 2009081412 03 OFCI 96 159N 502W 25
AL 90 2009081412 03 OFCI 108 169N 537W 25
AL 90 2009081412 03 OFCI 120 179N 573W 25
Member Since: September 23, 2005 Posts: 14 Comments: 11222
3379. KEEPEROFTHEGATE 12:45 PM GMT on August 14, 2009 Hide this comment.
here is the updated one just come out


107mph approching the area between St. Lucia and the Virgin Islands 5 days from now and strengthening quite rapidly. EEK
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3398. Skyepony (Mod)
Quoting seflagamma:
Skye, I noticed you were watching this "wave" yesterday before anyone was talking about it weren't you? (the one close to South Florida)


I've been eyeing it since 50W, surface obs since yesterday, since it was in an area where we could get alot of them. Mid level circulation has improved alot over night. That west wind is still there, a NW one has also popped up since, S of cuba to the SW of the new convection. I need a ship just N of the East end of Cuba. Suprised about the West coast of FL totally discounting this. One model had it as a TS hitting Tampa in 48hrs.
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Quoting Cotillion:


That's interesting, good spot. Do NHC really make forecasts for invests? I've not seen any lines for OFCI on them before, usually just the BAMM models.


Maybe they are about to upgrade this...
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting nrtiwlnvragn:
Interesting from the SHIPS file for AL90

FORECAST TRACK FROM OFCI

Indicates to me NHC has done a forecast track on 90L.

May be a typo, subject to revision by NHC.


That's interesting, good spot. Do NHC really make forecasts for invests? I've not seen any lines for OFCI on them before, usually just the BAMM models.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting heliluv2trac:
can anyone imagine what next week will be like on here


If its busy, admin will be quick to ban. I'll also be ready to put some on ignore.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting claimsadjuster:
Does anyone have the SAL map?


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can anyone imagine what next week will be like on here
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Does anyone have the SAL map?
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good morning ex-TD2 looking good prob TD2 at 11 of 5 today and 90L looking good prob TD3 by 5pm or 11pm and


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Quoting HurricaneKyle:


You can really see the Anti-cyclone fanning this thing out on that image. It's 'breathing'.

The anticyclone isnt centered directly over it. Its actually closer to the Cape Verdes. Thats why this is getting sheared by about 10 knots.
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Quoting Stormchaser2007:

It isnt that significant. It should be able to overcome.



You can really see the Anti-cyclone fanning this thing out on that image. It's 'breathing'.
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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.

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