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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NOT taking any chances guys and i've left my baby in my baby mama's care
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Quoting PimpCane:


Fail troll is fail.
Excuse me, are u calling me a troll?!?!
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Quoting Drakoen:
ZOMG MIAMI HIT !?!?!?! I am putting up shutters as we speak!!!


LOL!
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Quoting CaneWarning:


You should also evacuate to Canada. I read on here earlier that 90L was the end of Florida.


Let me know how their healthcare is ..
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Quoting watchingnva:


what is your problem seriously...

how about first off running the model all the way through first...

and once again...its over 11/12 days from here...at least...the islands have a much greater reason to be concerned right now.
ok, no need to get pist over a mistake, sorry.
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I would have to go with orange for right now, However, it would not surprise me at all if a code red comes up due to improved banding and convection organizing.. It looks good.
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Quoting WeatherStudent:
yup, it'll be us hitetr alright, with taht ridge in place, you knwo it. if itw ere setember or october clearly a fish, but in aug, olvidalo.

Go have a cold shower to wake ya self up.... when i quote what you say... most of it has red dots under it
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The problem is, TD 2 initial forecast was further east, now we are in the cone. It kept coming west.

90L started out as it is, and until it shows sign of turning wnw or nw, the models continue to shift west and west.
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Quoting IKE:


Has 90L slamming into the northern islands...Link

Has a vorticity going into SE LA from the Caribbean wave.


Yeap... almost ala Hurricane Hugo.
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Quoting Drakoen:
ZOMG MIAMI HIT !?!?!?! I am putting up shutters as we speak!!!
LMAO!
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Quoting Drakoen:
ZOMG MIAMI HIT !?!?!?! I am putting up shutters as we speak!!!


You should also evacuate to Canada. I read on here earlier that 90L was the end of Florida.
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Quoting canesrule1:
OH MY GOD!!! watch out Miami!!!



what is your problem seriously...

how about first off running the model all the way through first...

and once again...its over 11/12 days from here...at least...the islands have a much greater reason to be concerned right now.
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Quoting canesrule1:
true, i think Ana will be like Hugo.


Fail troll is fail.
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ZOMG MIAMI HIT !?!?!?! I am putting up shutters as we speak!!!
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Quoting AussieStorm:

B maybe C
It can't be C because there has been no renumber.
Quoting WeatherStudent:
sf get ready
Yup
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Quoting BenBIogger:


*facepalm*


*facepalm* <.. lol, I like that
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Also put me down for orange at 2, with a shot at red for 8.
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Quoting KEHCharleston:
Orange - will take it more than 2 days (48hrs) to develop

I have one for you. RE: Wishcasting
A) If enough people wishcast - it will have an effect on the storm
B) Wishcasting has no effect


b
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Quoting CaneWarning:


It's hard to see where it goes from the CMC. It could do a complete turn out to sea. We have a long time to watch.
true, i think Ana will be like Hugo.
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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

B maybe C
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Quoting canesrule1:
OH MY GOD!!! watch out Miami!!!



*facepalm*
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Quoting canesrule1:
If it continues its path it will (WNW)


It's hard to see where it goes from the CMC. It could do a complete turn out to sea. We have a long time to watch.
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Quoting OSUWXGUY:
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


Wouldn't be to to the proximity to land still? I would assume the bands on the southern quadrant could start building up towards the east later today and closing it it up some.
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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 - will take it more than 2 days (48hrs) to develop

I have one for you. RE: Wishcasting
A) If enough people wishcast - it will have an effect on the storm
B) Wishcasting has no effect
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Quoting cg2916:

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


Shouldn't we wait for Ana before we start naming Bill? Consensus here a couple of days ago was that 90L was destined to be Bill because TD2 was clearly going to be Ana. Now TD2 is barely alive. So perhaps we could hold off on naming storms two and three names ahead of the pack, maybe?
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for the 2pm TWO poll I say orange.
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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


Red. Looks too good, too fast.
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come on guys i dont think the metes no where this thing is going not even dr masters he didnt mention anything about it hitting the us or missing the us even the computer models arent sure so to say that we all should pay attention from mexico to east coast could get hit i mean know one really knows where these storms are going
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Quoting CaneWarning:


It's nowhere near Miami.
If it continues its path it will (WNW)
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Cape Verde Storms are the ones most likely to affect New England during the month of August and early September. Exception being Hurricane Bob in 1991.
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Quoting WeatherStudent:


throw it out ike, it also ha sit as a cat 5 so i dont think so, lol
U live in SFLA with me and Duffy, lol, what do u think of the CMC?
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547. IKE
Quoting WxLogic:
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.


Has 90L slamming into the northern islands...Link

Has a vorticity going into SE LA from the Caribbean wave.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
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
'

B. Red

I think we'll see red due to improved banding and convection closer to the center increasing...
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Quoting CaneWarning:


Too close for comfort...


exactly
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Quoting AussieStorm:

Glad to see you either woke up more, opened your eyes or fixed your keyboard keys.

LOL
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Quoting Acemmett90:

nice

My daughter was a server at both of the one's in St Lucie. Some of the managers are pervs. LOL not mentioning names, I'm just sayin..
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Quoting canesrule1:
OH MY GOD!!! watch out Miami!!!



It's nowhere near Miami.
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Quoting TreasureCoastFl:

orange
Red
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OH MY GOD!!! watch out Miami!!!

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About

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