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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2037. Drakoen
Quoting atmoaggie:

965 mb, 108knots @ 35 m...more sensical than the last run.
That one had cat 4 pressure with cat 2 winds.


lol
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ah never mind just go it on penn state.
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Quoting WPBHurricane05:
90L GFDL

965 mb, 108knots @ 35 m...more sensical than the last run.
That one had cat 4 pressure with cat 2 winds.
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Quoting WPBHurricane05:



Umm...965 knot is NOT a cat 3...its more like a cat "Holy Crap Al Gore Was Right!!!"


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Does the GFDL model only go up to 126 hrs?
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18z HWRF isn't up yet on fsu.
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Quoting DM21Altestic:
GFDL has 90L as a 965-knot category 3 MJO hurricane.


0.o umm excuse me? u mean a 965mb cat 3 major hurricane?Because for one 1000mph seems a little bullish .. for two Im not sure I know what a madden julian oscillation hurricane is ..
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2028. Seastep
Quoting atmoaggie:

And low level convergence simply isn't there (comes with the higher pressures)


I think it's worth watching. There is convergence around. Less with latest, but still.

15Z:



18Z:



21Z:

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Quoting DM21Altestic:
GFDL has 90L as a 965-knot category 3 MJO hurricane.



Umm...965 knot is NOT a cat 3...its more like a cat "Holy Crap Al Gore Was Right Run For Your Life!!!"
Member Since: July 31, 2006 Posts: 56 Comments: 8112
HWRF and GFDL aren't too far apart from each other. Very similar runs.
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Quoting IKE:
18Z GFDL.....only shows 43 knots on the run I've got?


Thats 02L
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Atlantic
green ball90L.INVEST
green ball02L.TWO

East Pacific
green ball10E.GUILLERMO
green ball09E.NINE

Central Pacific

West Pacific
green ball94W.INVEST
green ball93W.INVEST
green ball91W.INVEST
green ball10W.ETAU
green ball01C.MAKA
Member Since: May 21, 2006 Posts: 5091 Comments: 115256
That's a Cat 3.
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Quoting IKE:


Brain-fart....my bad....
Eeewwww
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Lol I was about to point and laugh at Ike too =P Like some mistakes I've made in the past couple of days, I am not alone.
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HWRF Minimum pressure-932 mb (LOL???)
Member Since: July 31, 2006 Posts: 56 Comments: 8112
2017. IKE
Quoting WPBHurricane05:


You are looking at the 02L run.


Brain-fart....my bad....
Member Since: June 9, 2005 Posts: 23 Comments: 37858
90L GFDL
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting StormW:
Good evening!
Ahhh finally! Start predicting for us StormW. :)
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Quoting IKE:
18Z GFDL.....only shows 43 knots on the run I've got?


You are looking at the 02L run.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
2013. IKE
18Z GFDL.....only shows 43 knots on the run I've got?
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting CybrTeddy:
Little change, not strengthening not weakening. I expect it to blow up during the night time hours.


Agreed at this point in time. Slow development, but we could see a Tropical Depression by 11 PM on Friday or 5 AM on Saturday if it becomes even more organized.
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Quoting Drakoen:
GFDL 18z 108knts@ 35m 90L


Can you post the link to that?
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Little change, not strengthening not weakening. I expect it to blow up during the night time hours.
Member Since: July 8, 2005 Posts: 259 Comments: 24161
Quoting amd:


thunderstorms are impressive, shear is surprisingly low. However, pressures are very high (around 1016 mb), and all convection is being enhanced by an upper level low. No real threat for now.

And low level convergence simply isn't there (comes with the higher pressures)
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2008. msphar
Whither Ana ? I thought somebody said she would be in town soon ? Looks like I have to evacuate from PR for personal reasons, neither weather related nor boat related. At the airport waiting for the flight. That impressive wave blew through late yesterday and this morning. For now back to the desert.
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Quoting StormW:
Good evening!


same to you Storm...
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2006. JRRP
west??
Link
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2005. Drakoen
GFDL 18z 108knts@ 35m 90L
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Quoting Weather456:
Pre Ike



90L


... I don't like that.
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2002. amd
Quoting HURRICANECAT5:
Any Comments on the wave north of Hisoaniola tonight?


thunderstorms are impressive, shear is surprisingly low. However, pressures are very high (around 1016 mb), and all convection is being enhanced by an upper level low. No real threat for now.
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Chuck says no more virus talk...

But GBguy88 is right, many 3rd party programs rely on IE being installed, so removing it is not reccomended. If you hate it that much then just use something else.
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000
ABNT20 KNHC 132340
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT THU AUG 13 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE REMNANT LOW ASSOCIATED WITH FORMER TROPICAL DEPRESSION TWO IS
LOCATED 1385 MILES EAST OF THE LESSER ANTILLES AND IS MOVING
WESTWARD ABOUT 10 MPH. THIS SYSTEM IS ACCOMPANIED BY A FEW SHOWERS
AND REGENERATION INTO A TROPICAL CYCLONE...IF AT ALL...WILL BE SLOW
TO OCCUR. THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

A BROAD AREA OF LOW PRESSURE ACCOMPANIED BY SHOWERS AND
THUNDERSTORMS IS CENTERED ABOUT 200 MILES SOUTH OF THE CAPE VERDE
ISLANDS. ALTHOUGH THERE HAS BEEN LITTLE CHANGE IN ORGANIZATION
DURING THE PAST SEVERAL HOURS...THIS SYSTEM HAS THE POTENTIAL TO
BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES
WESTWARD AT 10 TO 15 MPH. THERE IS A HIGH CHANCE...GREATER THAN 50
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

A LARGE AREA OF CLOUDINESS AND SHOWERS OVER HISPANIOLA...THE TURKS
AND CAICOS ISLANDS...AND THE SOUTHEASTERN BAHAMAS IS ASSOCIATED
WITH A TROPICAL WAVE INTERACTING WITH AN UPPER LOW. THIS ACTIVITY
IS EXPECTED TO SPREAD SLOWLY WEST OR WEST-NORTHWESTWARD DURING THE
NEXT DAY OR TWO. SURFACE PRESSURES ARE NOT FALLING AND UPPER-LEVEL
WINDS ARE NOT FAVORABLE FOR SIGNIFICANT DEVELOPMENT. THERE IS A
LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER AVILA

1999. IKE
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT THU AUG 13 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE REMNANT LOW ASSOCIATED WITH FORMER TROPICAL DEPRESSION TWO IS
LOCATED 1385 MILES EAST OF THE LESSER ANTILLES AND IS MOVING
WESTWARD ABOUT 10 MPH. THIS SYSTEM IS ACCOMPANIED BY A FEW SHOWERS
AND REGENERATION INTO A TROPICAL CYCLONE...IF AT ALL...WILL BE SLOW
TO OCCUR. THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

A BROAD AREA OF LOW PRESSURE ACCOMPANIED BY SHOWERS AND
THUNDERSTORMS IS CENTERED ABOUT 200 MILES SOUTH OF THE CAPE VERDE
ISLANDS. ALTHOUGH THERE HAS BEEN LITTLE CHANGE IN ORGANIZATION
DURING THE PAST SEVERAL HOURS...THIS SYSTEM HAS THE POTENTIAL TO
BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES
WESTWARD AT 10 TO 15 MPH. THERE IS A HIGH CHANCE...GREATER THAN 50
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

A LARGE AREA OF CLOUDINESS AND SHOWERS OVER HISPANIOLA...THE TURKS
AND CAICOS ISLANDS...AND THE SOUTHEASTERN BAHAMAS IS ASSOCIATED
WITH A TROPICAL WAVE INTERACTING WITH AN UPPER LOW. THIS ACTIVITY
IS EXPECTED TO SPREAD SLOWLY WEST OR WEST-NORTHWESTWARD DURING THE
NEXT DAY OR TWO. SURFACE PRESSURES ARE NOT FALLING AND UPPER-LEVEL
WINDS ARE NOT FAVORABLE FOR SIGNIFICANT DEVELOPMENT. THERE IS A
LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER AVILA
Member Since: June 9, 2005 Posts: 23 Comments: 37858
8:00 PM
the trough is expected to pic up speed as 90L decreases speed which means that curve we are all hoping for might not happen.
A few years back an IT guy friend of mine suggested Advanced System Care for Windows. One of the BEST free programs I've gotten.....EVER. IObit maintins and updates OFTEN and adds functionality like their new Security 360...among other things. HIGHLY recommended.
(I also use AVG Free and Spybot S&D...I've never had probs with my system)
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Quoting frostynugs:
to anyone with virus issues... first of all, get rid of internet explorer if you are using it to browse the web. use firefox (www.firefox.com) and ad block plus (it's a plugin you can download for it, google it) as drak mentioned. Avira antivir (free-av.com) and malwarebyte's anti-malware are 2 free programs that will keep you virus free as long as you update them and scan with them regularly. I have not had a virus give me trouble in almost 2 years as a result.


Well, you can get rid of IE if you want to, but I only use Firefox and Google Chrome to test my website code to be sure those users don't see something funny. IE is not the problem (well, v8 has some SSL issues) - I use Windows Defender (free) and Avast Pro (they also offer a free auto-updating version) and have had no problems anywhere on the internet.
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I, one of many, hopes that this future storm doesn't bother anyone. The GOM does not need another one, but then again, no one need it!
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1991. fire635
Just wanted to post on 1989... very good year for me. Guess I missed it
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1990. GBguy88
Quoting frostynugs:
to anyone with virus issues... first of all, get rid of internet explorer if you are using it to browse the web. use firefox (www.firefox.com) and ad block plus (it's a plugin you can download for it, google it) as drak mentioned. Avira antivir (free-av.com) and malwarebyte's anti-malware are 2 free programs that will keep you virus free as long as you update them and scan with them regularly. I have not had a virus give me trouble in almost 2 years as a result.


Do not get rid of internet explorer. I'm not sure about the new version of Windows (Vista?), but I know that prior versions will not allow you to remove internet explorer. If you do, your machine will not function properly, if at all. Just don't use it...internet explorer can't hurt you if you don't explore with it.
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Any Comments on the wave north of Hisoaniola tonight?
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1988. centex
Quoting jdjnola:
Looks like the moisture 90L is throwing off to its west is starting to push away the dry air in front of the-artist-formerly-known-as-TD2. Tonight's dmax should be interesting...
agree, but I think 90L got it's own moisture and the talk about TD2 clearing the way is not correct. TD2 not clearing anything.
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Quoting DM21Altestic:
My local news station meteorologist just said that "this African wave" will likely become a hurricane in the Gulf of Mexico in 7-10 days, so...
Who said that and where?
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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.