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 Tazmanian:



lol too funny


Holy crap...this is a weather blog, not a guess random events blog.... do you want us to predict the storm surge for the 3rd named storm this year too? Maybe we can "forcast" the tracks for the 2011 storm season.

Any more ridiculus polls?

How about using some real science for prediction? I tune in here to get a better understanding about how different weather patterns interact with tropical systems. I dont come here to create gossip and "fun" guessing games about things that can't possibly be predicted....

uggg....
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Quoting KATRINABILOXIGIRL:
No you haven't you've always kept me safe..thank you for that...just think it's a little interesting to see what goes on in here soemtimes

I could tell you two were related. Yer handles look a lot alike.
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KEEPS THE HONEST PEOPLE HONEST!!!!!!!!!!
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Quoting wunderkidcayman:

I think we need to watch ex-TD2 as well but knowing how weak it is I think it will likely to be a caribbean system


Possibly, but I think that's only if it were to remain an open-wave. If it were to reintensify, a northern track is more probable.
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2333. KEEPEROFTHEGATE (Mod)
Quoting DM21Altestic:

SHIPS says it'll strengthen much faster than that.
models are meant to be used for guidance only and do not depict final outcome things can and will change
Member Since: July 15, 2006 Posts: 163 Comments: 52217
Most of the models are now saying this could get into the Caribbean
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has any one noted how big 90L is ???
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Quoting BILOXISAINT2:
You dont need this blog... i have never let you down.. Have i?
No you haven't you've always kept me safe..thank you for that...just think it's a little interesting to see what goes on in here soemtimes
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Quoting keywestbrat:
Personally,
I am watching the blob over the DR, that one is closer to home, shallow hot bahamian water sometimes puts a firecracker under these storms.

Anyone from the DR here, whats your weather like at the moment?


...not from the DR, but from Turks & Caicos
We have had a wonderful afternoon... full overcast, so I got yard work done, being kept cool by the breeze.

Incredible & beautiful deep blood red sunset, and not a drop of rain yet. The barometer has been rock steady all day at about 1018, some gusts up to 30 mph this eve but still from the SE as usual.

CRS
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90L is NOT looking any better! Strong convection well away from the Center! LLC never had a burst of convection all day.. Like I said earlier this is going to be a slow developer and will move futher WEST than some model forecast right now...
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Quoting CaneWarning:


That map is scary. Most go through the islands towards PR and DR. The only good thing is if it hits DR it weakens it before any potential US strike. Of course, that's a bad thing if you are in DR. The one that really worries me is the one that goes to the west of Florida towards the GOM. Tampa could see a huge surge if it passes us by close enough.


In P'cola here... you guys as well as pcola have had our share. No development!
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Quoting kingzfan104:

how strong do you think it would be then? thank you so much for answering me. im just kinda jittery because wilma hurt us bad and it was only a cat 1 here in northern broward, a cat 3 or hell, with these model projects, even more, we could be in for a lot of trouble. again, thanks for the help


Sorry for the delay. I think since waters are very warm in the Bahamas it could be a major hurricane, unfortunately.
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Wow gator, simple question and you are all over me. Im no weather expert but apparently u are. Just putting it out there. In the Northeast no tropical storm of conseqence has occurred since Gloria in 1985, unless you count Bob in 1991!
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Quoting gator23:


Maybe we shouldnt talk politics.Email me if anything

Yeah, didn't really want to start that off into a discussion. Discover mag just set me off once I got a chance to look a couple days ago.
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Quoting KATRINABILOXIGIRL:
nope see what you've done.turned me into a weather junkie like you and the rest of alot of these people on here
You dont need this blog... i have never let you down.. Have i?
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Quoting FLHurricaneChaser:
Folks this is not going to be a Gulf storm. Lesser Antilles, Florida, and East Coast need to be watching this.

Early model runs showed that but they are starting to track farther south just like they did with TD2. All it takes is the long range models to be off by one degree and that is the difference from an east coast storm and a Gulf storm.
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What ever happened to Levi? I sure would love to get his take on this one.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
guys dont for get we have old TD 2 out there so we have too put up with TD 2 be for 90L all so TD 2 is trying too make a come back its trying to find lower shear
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Quoting FLHurricaneChaser:
Folks this is not going to be a Gulf storm. Lesser Antilles, Florida, and East Coast need to be watching this.


Proof?
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Quoting BILOXISAINT2:
ELIZABETH ARE YOU FRIGIN KIDDIN ME!
nope see what you've done.turned me into a weather junkie like you and the rest of alot of these people on here
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What is scary about 90L is how in line the models are this early. Even with TD2 there was a pretty good difference between the models. Esspecially with the Ensembles. Now all the models and Ensembles are lining up well with little outliers. Makes you start to have confidence in the models.

On a side note looks like we are in the 29% (Below average year of a named storm in the first half of August) if 90Lhold off for one more day. It could happen. Maybe TD tomorrow and TS ont he 16th.
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i honestly don't think half the people asking "where do you think it will go?" actually read the blog and realize that it's too soon to tell.. 5- 7 days at most before the mets could be somewhat sure of where it's going.. till then prepare your hurricane kits make sure you have your shutters in working order and then sit and wait till the NHC gives you an actual warning or watch..

-goes back to lurking and laughing at certain posts-
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Folks this is not going to be a Gulf storm. Lesser Antilles, Florida, and East Coast need to be watching this.
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Quoting HurricaneKyle:


Well, 90L's going to have an Anti-Cyclone to repel against shear.


Is it possible to even counteract shear??
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2310. gator23

Quoting atmoaggie:

Good. Bunch of alarmist, fruit-cake, bleeding heart liberal, lets regulate every gas that soaks up IR no matter the cost, the science is settled, we'll just interview the GE stokeholders about AGW and publish just in time for the house vote on cap-n-tax freaks, they are. Subscription canceled.
Thanks to you, I don't have to cancel cable, too. (Mr Biloxi Saint would be busy for a little while...then under-utilized)

Maybe we shouldnt talk politics.Email me if anything
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ELIZABETH ARE YOU FRIGIN KIDDIN ME!
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2307. KEEPEROFTHEGATE (Mod)
Quoting JLPR:
90L looking better

yep right on time convection should continue to expand from 11 pm till about 4 am edt wane a little during the day tomorrow and tomorrow night then the 2nd convective cycle commences sat afternoon with strong organization sat night and named after that
Member Since: July 15, 2006 Posts: 163 Comments: 52217
Quoting CaneWarning:



F. Ask me in about 7 days.



lol too funny
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Quoting BILOXISAINT2:
I have many. Lets talk at the mail box.
you do knowhich mail lady ur talking to right? the one ur related to!!
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Quoting kingzfan104:
2292- where is the actual center there?
Right where you see the L
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Quoting dcoaster:
Seeing some deep convection, but I'm still concerned that 90L is bound to run into some steep wind shear over the next few days...



Well, 90L's going to have an Anti-Cyclone to repel against shear.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting gator23:

Sorry I didnt see the first part, no we are not related they are owned by private investors

Good. Bunch of alarmist, fruit-cake, bleeding heart liberal, lets regulate every gas that soaks up IR no matter the cost, the science is settled, we'll just interview the GE stokeholders about AGW and publish just in time for the house vote on cap-n-tax freaks, they are. Subscription canceled.
Thanks to you, I don't have to cancel cable, too. (Mr Biloxi Saint would be busy for a little while...then under-utilized)
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2298. HadesGodWyvern (Mod)


Shallow Low [1004 HPA] NEAR 6.0S 90.0E.
Member Since: May 24, 2006 Posts: 48 Comments: 43646
Quoting hurricane23:


23 did you listen to the .B.B. show? Pretty interesting. StormW and Bob both sounded concerned about 90L. What are your thoughts on this system?
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting KATRINABILOXIGIRL:
yay....thanks for the info GO SAINTS!!! and if you have any links that I can follow for the models other than looking on the weather channel stuff let me know OK?
I have many. Lets talk at the mail box.
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Quoting BiloxiIsle:
Why does the GFS 18 model tend to bring 90L in the Gulf, but the others runs do not? Just curious.
They will change from run to run. Later it will have it go to GA.....LOL
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Seeing some deep convection, but I'm still concerned that 90L is bound to run into some steep wind shear over the next few days...

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Quoting hurricane23:


That map is scary. Most go through the islands towards PR and DR. The only good thing is if it hits DR it weakens it before any potential US strike. Of course, that's a bad thing if you are in DR. The one that really worries me is the one that goes to the west of Florida towards the GOM. Tampa could see a huge surge if it passes us by close enough.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting BILOXISAINT2:
YES THE SAINTS GAME WILL BE ON CH.18 ALONG THE GULF COAST IN ALL CABLEONE SYSTEMS. I VERIFIED AND HOOKED UP THE EQUIPMENT TODAY MY SELF...ENJOY
yay....thanks for the info GO SAINTS!!! and if you have any links that I can follow for the models other than looking on the weather channel stuff let me know OK?
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Hello WU...I am a long term lurker, who used to catch WU via BBS even back to the late '80's. My last job was an emergency mangager, at our petrochemical facility. Our mgt. would always wonder how I was able to keep them abreast on the absolute latest during hurricane preparation.

Of course my secret was watching WU. Hope I can contribute.
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Why does the GFS 18 model tend to bring 90L in the Gulf, but the others runs do not? Just curious.
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.