New tropical depression could form off the coast of Africa

By: Dr. Jeff Masters , 1:12 PM GMT on September 25, 2009

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A tropical wave (99L) is located near 15N, 30W, about 300 miles west of the Cape Verdes Islands. This wave has seen an increase in heavy thunderstorm activity this morning, and low-level spiral bands have formed. The system can already be classified as a tropical depression using the satellite-based Dvorak technique. This morning's QuickSCAT pass showed a loose but closed circulation, with top winds of 30 mph in the heaviest thunderstorms. Wind shear is moderate, about 10 - 20 knots. There is a modest amount of dry air to 99L's west that does not appear to be interfering with the storm's organization.


Figure 1. Morning visible satellite image of Invest 99L (left side of image) and a new tropical wave moving off the coast of Africa.

As 99L moves west-northwest over the next two days, sea surface temperatures will cool by 1°C and winds shear will remain in the moderate range. Some dry air may also affect the storm. These conditions give 99L a good chance of forming into a tropical depression, and NHC has given the system a moderate (30 - 50%) chance of developing into a tropical depression by Sunday. By Monday, wind shear will increase to the high range, 20 - 30 knots, and 99L will probably weaken or be torn apart. None of the computer models forecast development of 99L or any other system in the Atlantic over the next seven days.

A new tropical wave with plenty of heavy thunderstorm activity and some spin is moving off the coast of Africa today. This wave is under a moderate amount of wind shear, 10 - 20 knots, and has some potential for development this week as it moves west or west-northwest past the Cape Verdes Islands.

The latest wind shear forecasts from our major computer models show high values of wind shear affecting most of the tropical Atlantic for the next ten days. This is typical for an El Niño year, and it will be difficult for any storms to get to hurricane strength over the next ten days because of the high shear. The latest 16-day GFS forecast predicts wind shear will decline some by the 2nd week of October, though.


Figure 2. Wind shear forecast for Thursday, October 2 at 00 UTC made by last night's 00Z run of the GFS model. Wind shear is expected to be high over most of the tropical Atlantic for the next ten days, including the Caribbean. Wind shear values below 8 m/s (about 15 knots, red colors), are typically needed to support tropical storm formation.

Jeff Masters

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LOL...me thinks the Iceman is posting through spirit laced glasses. I'd post an image, but I wouldn't know what beer to give credit to....
Member Since: Posts: Comments:
618. JLPR
Quoting KoritheMan:


He's from Puerto Rico.


yay! you remember lol XD
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Quoting iceman55:
JLPR stop attacks me .u will get ban.


He wasn't attacking you, inasmuch as he was asking a question.
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Quoting iceman55:
im not cry .im 28 old man.
IF that is true, which I HIGHLY DOUBT, very sad !!!!!!!!!!!!!!!!
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614. JLPR
Quoting moonlightcowboy:


A W E S O M E! This year for sure it seems, so far at least, El Nino has been our friend! ;) Hope it stays that way!

Take care, JLPR and all!


Take care too :)
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613. JLPR
Quoting iceman55:
JLPR stop attacks me .u will get ban.


lol do you consider that an attack even with the smiley face? XD

I am making a point, and I believe its very valid.

Very well im off to bed, TD 8 surviving but not strengthening and nothing else.
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Quoting iceman55:
KoritheMan haha new tv show.


You mean this one?

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Quoting iceman55:
JLPR stop attacks me .u will get ban.
now look, you made him cry again...
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Quoting KoritheMan:


Are you kidding? This is the greatest entertainment to be found on this blog in many years.




ok has long has they dont take it too far oh well they made be banned by AM any way
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Quoting JLPR:


great =D
everything is nice here, a week of rainy days seem to have come to an end and the sun is showing its face more :)


A W E S O M E! This year for sure it seems, so far at least, El Nino has been our friend! ;) Hope it stays that way!

Take care, JLPR and all!
Member Since: Posts: Comments:
Quoting Tazmanian:
hunkerdown and iceman55 are both going too be injoying a 24hr banned if they dont take this out of dr m blog and take it too there own blogs


they need too STOP!


Are you kidding? This is the greatest entertainment to be found on this blog in many years.
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Quoting iceman55:
I must agree u not from usa oh opps my bad


jlpr


He's from Puerto Rico.
Member Since: Posts: Comments:
hunkerdown and iceman55 are both going too be injoying a 24hr banned if they dont take this out of dr m blog and take it too there own blogs


they need too STOP!
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600. JLPR
Quoting iceman55:
JLPR are u from usa


kinda lol XD
Puerto Rico

I ask that since how does a person from a place in which the main language is Spanish and not English write better in English than a person that uses the language everyday?

are you writing that way on purpose?
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597. JLPR
Quoting moonlightcowboy:


Good, JLPR! It's FRIDAY! Hope things are good with you down in the Caribbean paradise!


great =D
everything is nice here, a week of rainy days seem to have come to an end and the sun is showing its face more :)
Member Since: Posts: Comments:
Quoting SWFLgazer:
Must be a slow night in the tropics if the worst that happens is a "Yes hed, no he didn't"
argument.


lmao

This has certainly been entertaining, to say the least.

Rather childish, as well.
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Quoting JLPR:


wow long time no see
how you doing? :D


Good, JLPR! It's FRIDAY! Hope things are good with you down in the Caribbean paradise!
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589. JLPR
Quoting iceman55:
JLPR haha


yeah ha...ha

but I must agree with Hunkerdown you do get me annoyed sometimes with the way you write

from where are you? Do you live in the US?
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Quoting btwntx08:
am mad at hunkerdown grrr!
somebody must be having a sleep over
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Must be a slow night in the tropics if the worst that happens is a "Yes hed, no he didn't"
argument.
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585. JLPR
Quoting moonlightcowboy:


But, if you could just get Atmo to act right! ;P


wow long time no see
how you doing? :D
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Member Since: Posts: Comments:
good evening from Seattle
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580. JLPR
Quoting hunkerdown:
what are you, his dad ?


so the problem is iceman's poor grammar?
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Honestly though, hunker is obviously being blunt and condescending, but if I were iceman, I'd take that as an opportunity to improve myself, as a means to disprove hunker's notion that the man can't speak for himself.

But that's just me, I guess. Obviously, not everyone is that mature around here.
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Quoting btwntx08:
ur the man iceman
what are you, his dad ?
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Quoting pearlandaggie:
549. trust me...i've been banned for criticizing the poor grammar of those worse than my 3rd grader! lol


But, if you could just get Atmo to act right! ;P
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571. JLPR
So what the problem tonight? XD
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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.