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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OH MY GOD!!! watch out Miami!!!

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Pretty good spiral banding with 90L and some convection starting to fire close to the center...

There is a relative lack of banding in the northeast quadrant...and I'm not sure if it has to do with dryer air from the Sahara being entrained or if it's just a lack of surface convergence???

Navy Africa Visible Loop
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Quoting IKE:
12Z CMC...

Oh heck no! Also, at the last frame, near Africa, you can see TS Bill.
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Quoting IKE:


Looks like 90L goes north of the islands...looks like it's fixing to do a turn NW...


Too close for comfort...
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Afternoon All,
I see a biggus blobus approaching the Turks and Caicos... where did that come from? but hey we do need the rain...
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Quoting btwntx08:
poll time what is the 2pm TWO gonna say 90L:

A.same orange
B.red
c.td
vote now poll closes in 20 minutes

orange
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Quoting canesrule1:
is there one in miami?

I have a MVP card there.. haha
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Quoting Acemmett90:

were still growing but will do not have one i miami as of yet but we are the fastest growing chain in florida
cool.
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Quoting WeatherStudent:
it'll prob. be code red at 2pm.

Glad to see you either woke up more, opened your eyes or fixed your keyboard keys.
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526. IKE
Quoting IKE:
12Z CMC...


Looks like 90L goes north of the islands...looks like it's fixing to do a turn NW...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting KEEPEROFTHEGATE:
Wow what a B!tc#, looks like miami is in anger with that graph!
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456 - don't look at the CMC...
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In regards 12Z NOGAPS... it still believes TD#2 has a chance and is now starting to pick up 90L but not depicting it as strong as it approaches the norther Leeward Islands... so track wise is similar to GFS but a bit further N.
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Quoting canesrule1:
Im sending an e-mail to the NHC about why is 90L not a TD yet.


If I got that message I would "LOL!!!"
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Quoting 7544:
ok dont laugh but it covers the whole eastern seaboard this run from fla to and up so longgated lol

Link


You're stating the obvious.

Now this shows the high moving northeast and away, right
Quoting Acemmett90:

i am not trying to portray doom and gloom if i wanted to i would say were a ganna die what i ment by this is we should a be prepared and ready if something bad happens
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519. 7544
ok writing this down this is the six state that the gfs wants to take 90l too but looks like it may go back to fla in the next couple of runs . just keep watching the high thats the main key stay tuned
Member Since: May 6, 2007 Posts: 0 Comments: 6696
Quoting Acemmett90:

it a sports grill on the east coast of fla we are think of opening in tampa in the next couple of years
by the way im still laughing form your last comment
is there one in miami?
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12Z CMC
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516. IKE
12Z CMC...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
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Quoting 900MB:
Hey all! Long, long time. I lurk but tend to keep my mouth shut and keep it to the experts.
Just my 2 cents: TD2 Has a prayer, but with 90L it is we that should be saying our prayers- this could be the first major of the season, especially with TD2 sucking in the dry air north, clearing the deck for 90L.


I agree.
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Quoting Acemmett90:

it a sports grill on the east coast of fla we are think of opening in tampa in the next couple of years
by the way im still laughing form your last comment


OK, when you build one in Tampa I'll try it out.
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Quoting NOLABean:
Hi guys - first post of the year since I'm a reader more than a poster. Thanks to my location am much more interested in the Atlantic season ramp-up than other areas.

Have been seeing a few allusions around here by local mets that they are starting to watch the GOM a little. I'm thinking nothing to worry about except maybe a potential heavy rain maker... any thoughts? I get that the lingering trof could pose some development, but is there really enough time for anything to happen out there outside of maybe a TD3 at best?


Tropical systems have the potential to spin up very quickly. See Hurricane Humberto, 2007.
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Im sending an e-mail to the NHC about why is 90L not a TD yet.
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Troppical weather gives me more suspense than any of the thrillers I read. I always have a bad feeling if it looks like something major is forming - but I also know that wait and see is the only attitude to take. So many amazing things happen to storms on their way from the African Coast to their "end" that waiting is the only solution. On the way the curl and loop and disappear and reappear and waver and job, all the while with all of us like the Verizon team on TV following along with every wobble - which I think is why this is such a popular blog. I don't think it's necessarily wishcasting, it's more like curiosity about what new thing will we see this year, and is it one that will hurt us. Anyway, have a good day everyone.
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Quoting presslord:



...well...as I live in South Carolina...I won't be saying much on this subject....


HAHAHAHAHAHAH!!!
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I sure hope... 90L doesn't take the route for the Greater Antilles for a hit to PR and Hispanola... these two islands got enough with 97L specially Hispanola with all the flooding it had... thankfully not major disasters that I've heard from there yet.

If it does decide to take that southerly course... sure hope it keeps south enough to not have them feel the the full brunt of the force.
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Quoting Drakoen:


He would be jumping up and down in his cage
LMAO
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Quoting CaneWarning:



Florida public education at work...



...well...as I live in South Carolina...I won't be saying much on this subject....
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Quoting cchsweatherman:


If that did happen, Joe Bastardi would have a field day gloating about his forecasts.


He would be jumping up and down in his cage
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Quoting Acemmett90:

i am not trying to portray doom and gloom if i wanted to i would say were a ganna die what i ment by this is we should a be prepared and ready if something bad happens


What is Duffy's? We don't have one in Tampa.
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Quoting CaneWarning:



Florida public education at work...
ROFLMAO!!!!!
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Quoting AussieStorm:

Are you typing with your eye's closed or did you just wake up?



Florida public education at work...
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493. IKE
Quoting WxLogic:


LOL... quite true IKE. To me is more like a training exercise to be able to get a general feel about the trends. :)


8-14 day prognostic discussion talks about a strong trough in the east. Based on where 90L is at now, it's doubtful it reaches the gulf coast if that time period verifies. That's over 4 thousand miles it has to travel in say 11 days. It better be moving 15-20 mph.

Odds are, for now....islands...beyond that is a ?.

If I had to guess...curves east of USA coast.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
On a Sad note for many, Les Paul Dies at 94

for Les,Play on in the Big Gig in the Sky bro,..

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Quoting Gustavike:
The GFS showed a smooth bullfight 06 today z but to 12 z reaffirms that a great hurricane could affect to the Antilles Majors within 180 hours. Meanwhile the TD2 does not occur by won and develops convection again. I believe that the future of this system is still uncertain Dr Jeff.
why is it that some models take 90L to the north before Florida! is there a weakness in the Bermuda high?
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Good Afternoon folks

Press - Portlight Response Plan looks very good. I will give it a bit more thought, but I can not think of anything that I would suggest to add to the plan.

This loop is sort of fun. Shows the SAL attempting to hem in TD2, and shows TD2 throwing it back off.
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Quoting WeatherStudent:
exactly, wx, if itw ere early, mid, or even late september i would ahve had more faiath in taht trhough, but its august for the love of god, emaning that the ridge still rpevails throughout most of the basin, which will affect tc.

Are you typing with your eye's closed or did you just wake up?
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I think that it's more likely overhang from a long Birthday party.
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Quoting Gustavike:
The GFS showed a smooth bullfight 06 today z but to 12 z reaffirms that a great hurricane could affect to the Antilles Majors within 180 hours. Meanwhile the TD2 does not occur by won and develops convection again. I believe that the future of this system is still uncertain Dr Jeff.


It looks like it would eat the islands, then PR, then Haiti.
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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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