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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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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Quoting Skyepony:


On 02L Ships is being out preformed by GFNI & NGPI & perhaps others. Compare the Early-cycle intensity guidance to the last link I left.
regular english please. im not really in on meteorology lingo. which is the best wind forecast model?
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Quoting gator23:

Never been, Im out of Miami

Sorry, been to both Miami and Silver Spring 3 times each. I'd take Silver Spring over Miami any day to either visit or move to.
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2284. gator23
Quoting atmoaggie:

About that, are y'all related to Discover mag? I hope not.
BTW, I like the digs in Silver Spring. Nice.

Sorry I didnt see the first part, no we are not related they are owned by private investors
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2283. 7544
wow just seen the 18 gfs ouch was that the newest run
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Member Since: May 14, 2006 Posts: 8 Comments: 13807
90L raking the antilles and riding up the bahama chain??

Link
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Thank you BiloxiSaints2!
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With TD #2 the computer models had a wide spread at the "invest" stage. The Early model readings typically flop all over the place.

With invest 90L it is surprising to see such model agreement at this early stage. The main models look like a rope 3 days out then diverge a little bit before converging again. It looks like the lesser Antilles are in the cross hairs. 90L definately not looking like a "fish" storm.
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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
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2276. gator23
Quoting atmoaggie:

About that, are y'all related to Discover mag? I hope not.
BTW, I like the digs in Silver Spring. Nice.

Never been, Im out of Miami
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you guys are too funny
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2274. Skyepony (Mod)
Quoting kingzfan104:
and what is the best model as far as ind intensity? is it ships?


On 02L Ships is being out preformed by GFNI & NGPI & perhaps others. Compare the Early-cycle intensity guidance to the last link I left.
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2273. JLPR
90L looking better

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2272. gator23
Quoting DM21Altestic:
It's definately possible that it will go in the gulf lol

Its Definately possible Space Aliens will visit you tonight lol
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Quoting gator23:

I work for Discovery Channel

About that, are y'all related to Discover mag? I hope not.
BTW, I like the digs in Silver Spring. Nice.
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Quoting Tazmanian:
ok all whats do a poll on where its going to go and will see oh is right at the end


A it will hit FL

B it will hit TX

C it wil; hit any where along the gulf coast

D it will hit the E Coast some where

now dont start yelling right a way about this one or E fish storm take your time and pick



F. Ask me in about 7 days.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
2269. jdjnola
Greater than or equal to 0% and less than or equal to 100%.

Does that make it 50-50?

Got me again.
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I pick F... way to early to f***** start predicting where it'll go
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2266. gator23
Quoting Tazmanian:
ok all whats do a poll on where its going to go and will see oh is right at the end


A it will hit FL

B it will hit TX

C it wil; hit any where along the gulf coast

D it will hit the E Coast some where

now dont start yelling right a way about this one or E fish storm take your time and pick


F. WAY WAY WAY WAY WAY TOO EARLY
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Quoting Tazmanian:
ok all whats do a poll on where its going to go and will see oh is right at the end


A it will hit FL

B it will hit TX

C it wil; hit any where along the gulf coast

D it will hit the E Coast some where

now dont start yelling right a way about this one or E fish storm take your time and pick
F. Nobody knows
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Quoting atmoaggie:

And how many cat 5s at landfall have we had in the GoM? 1. Not like it hasn't been warm before.
But sensationalism sells ad time. Expect TWC and CNN "science" to pick up on this soon.


The local news people have picked it up for sure. I'm pretty sure that if I don't watch the 11 PM news I'm going to miss a huge development...then they'll tell me to watch the 5 AM, 6 AM and 7 AM news...then Noon and then 5 PM and then 6 PM...either that or I face certain death.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
ok all whats do a poll on where its going to go and will see oh is right at the end


A it will hit FL

B it will hit TX

C it wil; hit any where along the gulf coast

D it will hit the E Coast some where

now dont start yelling right a way about this one or E fish storm take your time and pick
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90L is going to be a slow developing system, which means that it will move more WEST than some of the more nothern models...def not fish storm!!
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BiloxiSaint2-totally off topic but have to ask..is the Saints game going to be on TV tomorrow, and if so, what channel.

Hope 90L doesn't come to the GOM (thats tropic related)
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2259. gator23
Quoting atmoaggie:

And how many cat 5s at landfall have we had in the GoM? 1. Not like it hasn't been warm before.
But sensationalism sells ad time. Expect TWC and CNN "science" to pick up on this soon.

I work for Discovery Channel
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Quoting gator23:

No one can answer this. not even god.

And how many cat 5s at landfall have we had in the GoM? 1. Not like it hasn't been warm before.
But sensationalism sells ad time. Expect TWC and CNN "science" to pick up on this soon.
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Quoting gator23:

That seems accurate but development is not forecast
Quoting gator23:

That seems accurate but development is not forecast


Thanx Gator 23. I know that noaa is giving it little chance for development, but have seen some surprises in my day!
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Quoting jdjnola:


Greater than or equal to 0% and less than or equal to 100%.

Does that make it 50-50?
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2253. gator23
Quoting DM21Altestic:
Florida...

is a state with a population 18,328,320 whose capital is Tallahassee and whose residents are known as Floridians
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Quoting gator23:

and pretty ridiculous...


I wouldn't go that far. With the information we have available it looks possible. It's a tropical weather discussion and I think its perfectly reasonable for them to have educated speculation.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
It has to be. Been watching this stuff for years. Most of these folks wish for something to happen. having been thru Betsy,Camille,Fredric.Elena,katrina, I am hoping for NOTHING.
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2250. jdjnola
Quoting HurricaneLovr75:
What up all.

What are the chances of invest 90 being a Cat 5 at landfall if it reaches the GOM? Asking cuz the GOM is so warm.


Greater than or equal to 0% and less than or equal to 100%.
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Quoting squirrel61:
... I live in a hurricane hotspot...

Who, within 100 km of any coast on any seas doesn't?
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there is a great deal of 'straight up and accurate' information on this site...but if you're depending on the Comments section of a blog for that then you deserve whatever misfortune befalls you...
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2247. gator23
Quoting HurricaneLovr75:
How many people think the Northeast US is over due to be hit with a Hurricane?

dude, your killing me...
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2245. gator23
Quoting CaneWarning:


It's all speculation...

and pretty ridiculous...
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How many people think the Northeast US is over due to be hit with a Hurricane?
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Quoting clwstmchasr:
Baromter Bob and StormW are on and talking about 90L... Saying that somewhere in the U.S. in the next 10 days Hurricane Watches will probably be issued....

"Hurrincane watches"??? We don't even have a tropical depression, it is over 3,000 miles and we're talking about potential hurricane watches. Are you sure you heard right? It is way too early to have that conversation.


It's all speculation...
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting BILOXISAINT2:
No Way!
yes way. what's ur take on things...just a wait and see right?
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guys whats wait in tell the storm gets too 50W then we will no more for sure where it will go then
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No Way!
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2238. Melagoo
Quoting HurricaneLovr75:
What up all.

What are the chances of invest 90 being a Cat 5 at landfall if it reaches the GOM? Asking cuz the GOM is so warm.


Kinda Early ...
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2237. jdjnola
The-artist-formerly-known-as-TD2 is the "low pressure remnant" (per the NHC) that just won't die.
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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.