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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Quoting Stormchaser2007:

It isnt that significant. It should be able to overcome.



You can really see the Anti-cyclone fanning this thing out on that image. It's 'breathing'.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Interesting from the SHIPS file for AL90

FORECAST TRACK FROM OFCI

Indicates to me NHC has done a forecast track on 90L.

May be a typo, subject to revision by NHC.
Member Since: September 23, 2005 Posts: 14 Comments: 11215
that little carrib thingy could get really interesting when it hits those extremely hot waters of the GOM.....regardless...surfers get ready!!!
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Quoting java162:
looks like invest 90 is being sheared..

It isnt that significant. It should be able to overcome.

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Quoting ackee:
when was the last time the NE carrb had a major hurricane ?

Omar last year.
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3381. java162
looks like invest 90 is being sheared..
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IF EXTD2 can keep convection over its LLC then it should become a TD again at 5pm. 90L should be called sometime tomorrow.
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3379. KEEPEROFTHEGATE (Mod)
here is the updated one just come out

311

WHXX01 KWBC 141243

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

1243 UTC FRI AUG 14 2009



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL902009) 20090814 1200 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

090814 1200 090815 0000 090815 1200 090816 0000



LAT LON LAT LON LAT LON LAT LON

BAMS 12.1N 26.5W 12.7N 29.7W 12.7N 33.8W 12.4N 38.0W

BAMD 12.1N 26.5W 12.3N 29.1W 12.5N 32.0W 12.7N 35.3W

BAMM 12.1N 26.5W 12.4N 29.5W 12.4N 33.1W 12.2N 36.9W

LBAR 12.1N 26.5W 12.4N 29.4W 12.8N 33.0W 13.3N 37.1W

SHIP 25KTS 29KTS 38KTS 49KTS

DSHP 25KTS 29KTS 38KTS 49KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

090816 1200 090817 1200 090818 1200 090819 1200



LAT LON LAT LON LAT LON LAT LON

BAMS 11.7N 42.2W 10.9N 48.4W 12.3N 51.4W 17.5N 56.4W

BAMD 13.0N 38.9W 14.1N 46.1W 15.2N 52.4W 16.7N 58.3W

BAMM 11.9N 40.7W 12.0N 46.8W 13.8N 51.2W 17.4N 57.2W

LBAR 13.6N 41.6W 13.9N 50.3W 14.9N 52.8W .0N .0W

SHIP 59KTS 77KTS 89KTS 93KTS

DSHP 59KTS 77KTS 89KTS 93KTS



...INITIAL CONDITIONS...

LATCUR = 12.1N LONCUR = 26.5W DIRCUR = 280DEG SPDCUR = 13KT

LATM12 = 11.6N LONM12 = 24.0W DIRM12 = 276DEG SPDM12 = 9KT

LATM24 = 11.6N LONM24 = 22.5W

WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 25KT

CENPRS = 1008MB OUTPRS = 1012MB OUTRAD = 200NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN

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3378. ackee
when was the last time the NE carrb had a major hurricane ?
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African wave train last 21 hours


all aboard!!!!!

rollin rollin rollin...those lows keep formin......
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Morning all! Long time lurker, first time poster. I know that this isn't tropical weather per se, but I couldn't resist showing everyone the nice circulation on the Green Bay radar this morning. Quite odd!

Link

I've always thought that tropical storm like circulation in land based storms was fascinating.
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3373. jipmg
Quoting seflagamma:
you know, last year on my Birthday, 8/19, I was home all day, alone, no one bothering me (everyone was at work) and I got to watch TS Fay, travel back and forth across the State of Florida all day long. It was sort of a neat birthday present.

BUT I would rather NOT be preparing for a storm to hit us this year on my birthday!


My birthday wish was to experience a hurricane, and I got it, August 26th when miami was hit by Hurricane Katrina, it was an amazing experience and even sense i've been obsessed with meteorological phenomenons.
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3371. IKE
90L is on it's way...gathering it in....be back soon....
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3370. java162
Quoting IKE:
GFDL looks bad too.

Get ready if you live in the islands....


i'm ready. i live on the island of dominica and has never been in a major hurricane. looks like thats about to change
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Quoting Stormchaser2007:


They're always called that.


Ah, I guess I normally don't pay much attention to it.
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Quoting CaneWarning:
Keeper - I see that calls it Tropical Depression Invest 90L...


They're always called that.
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you know, last year on my Birthday, 8/19, I was home all day, alone, no one bothering me (everyone was at work) and I got to watch TS Fay, travel back and forth across the State of Florida all day long. It was sort of a neat birthday present.

BUT I would rather NOT be preparing for a storm to hit us this year on my birthday!
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3366. IKE
GFDL looks bad too.

Get ready if you live in the islands....
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Quoting IKE:


Just posted by Keeper.

From what I've read from mets along the gulf-coast in their discussions, none of them mention the blob headed for the GOM as anything more then rain.

Maybe it changes later.


Tampa mets keep calling it a tropical wave that will actually make our chances for rain go down as it moves by us.
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What are the "unfavorable conditions" in the GOMEX that NOAA refers too?
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Keeper - I see that calls it Tropical Depression Invest 90L...
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3362. IKE
Quoting CaneWarning:


Are the new runs out this morning?


Just posted by Keeper.

From what I've read from mets along the gulf-coast in their discussions, none of them mention the blob headed for the GOM as anything more then rain.

Maybe it changes later.
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CMC looks bad too.
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{{Baja}}} Hello back at ya!
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3359. KEEPEROFTHEGATE (Mod)
618

WHXX04 KWBC 141118

CHGQLM

ATTENTION...NATIONAL HURRICANE CENTER



NCEP COUPLED GFDL HURRICANE MODEL FORECAST MADE FOR



TROPICAL DEPRESSION INVEST 90L



INITIAL TIME 6Z AUG 14



DISCLAIMER ... THIS INFORMATION IS PROVIDED AS GUIDANCE. IT

REQUIRES INTERPRETATION BY HURRICANE SPECIALISTS AND SHOULD

NOT BE CONSIDERED AS A FINAL PRODUCT. PLEASE SEE THE TPC/NHC

OFFICIAL FORECAST.





FORECAST STORM POSITION



HOUR LATITUDE LONGITUDE HEADING/SPEED(KT)



0 11.7 24.8 275./ 8.0

6 12.6 26.6 295./19.3

12 12.6 28.6 271./20.3

18 12.3 30.4 261./17.5

24 11.9 31.8 252./14.4

30 11.6 33.1 258./13.2

36 11.3 34.6 258./15.0

42 11.2 35.5 264./ 8.3

48 11.7 36.8 291./13.4

54 12.1 38.1 286./14.0

60 12.7 40.0 290./19.2

66 13.7 42.0 295./22.1

72 14.1 44.4 279./23.3

78 14.4 46.3 281./18.7

84 15.0 48.2 287./19.5

90 15.2 49.9 276./16.4

96 15.7 51.7 286./17.6

102 16.1 53.3 284./16.3

108 16.6 55.0 286./16.5

114 16.9 56.5 281./14.7

120 17.4 58.2 286./17.5

126 17.9 59.9 287./16.6

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Skye, I noticed you were watching this "wave" yesterday before anyone was talking about it weren't you? (the one close to South Florida)
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(((( Gamms ))) Mornin!!!
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Oooh, that's interesting.

000
WHXX01 KWBC 141233
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1233 UTC FRI AUG 14 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE TWO (AL022009) 20090814 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090814 1200 090815 0000 090815 1200 090816 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 14.6N 41.7W 15.3N 43.8W 16.0N 46.4W 17.3N 49.8W
BAMD 14.6N 41.7W 15.4N 44.0W 16.4N 46.6W 17.7N 49.5W
BAMM 14.6N 41.7W 15.2N 43.7W 15.8N 46.1W 16.7N 48.9W
LBAR 14.6N 41.7W 15.2N 44.0W 15.9N 46.5W 16.9N 49.6W
SHIP 25KTS 27KTS 31KTS 35KTS
DSHP 25KTS 27KTS 31KTS 35KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090816 1200 090817 1200 090818 1200 090819 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 18.8N 54.1W 22.3N 62.2W 25.5N 68.6W 27.8N 72.2W
BAMD 19.1N 52.4W 21.6N 58.0W 23.1N 63.0W 23.2N 67.5W
BAMM 17.5N 52.3W 19.4N 59.5W 21.0N 66.2W 22.1N 72.1W
LBAR 18.1N 53.1W 20.9N 59.9W 24.4N 65.4W 26.3N 54.5W
SHIP 39KTS 47KTS 53KTS 55KTS
DSHP 39KTS 47KTS 53KTS 55KTS

...INITIAL CONDITIONS...
LATCUR = 14.6N LONCUR = 41.7W DIRCUR = 275DEG SPDCUR = 12KT
LATM12 = 14.3N LONM12 = 39.2W DIRM12 = 276DEG SPDM12 = 11KT
LATM24 = 14.0N LONM24 = 37.2W
WNDCUR = 25KT RMAXWD = 40NM WNDM12 = 25KT
CENPRS = 1008MB OUTPRS = 1012MB OUTRAD = 150NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN



That's the most bullish I've seen the SHIPS on ex-TD2 in a while.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting IKE:
BAM looks bad for the islands....


Are the new runs out this morning?
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Quoting Skyepony:
West wind on the east end of cuba, just popped up south of that blob. Nowcoast


Hi Skye,

What does that mean?
You are talking about the "rain maker" just off shore aren't you?

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3353. IKE
BAM looks bad for the islands....
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3352. KEEPEROFTHEGATE (Mod)
988

WHXX01 KWBC 140645

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

0645 UTC FRI AUG 14 2009



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL902009) 20090814 0600 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

090814 0600 090814 1800 090815 0600 090815 1800



LAT LON LAT LON LAT LON LAT LON

BAMS 11.7N 25.0W 12.4N 28.0W 12.7N 31.7W 12.6N 36.0W

BAMD 11.7N 25.0W 11.9N 27.7W 11.9N 30.4W 11.9N 33.5W

BAMM 11.7N 25.0W 12.2N 27.8W 12.3N 31.0W 12.3N 34.8W

LBAR 11.7N 25.0W 11.9N 27.5W 12.2N 30.5W 12.5N 34.2W

SHIP 25KTS 29KTS 38KTS 48KTS

DSHP 25KTS 29KTS 38KTS 48KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

090816 0600 090817 0600 090818 0600 090819 0600



LAT LON LAT LON LAT LON LAT LON

BAMS 12.0N 40.2W 10.8N 47.2W 11.9N 50.4W 16.5N 55.4W

BAMD 12.1N 36.9W 12.9N 44.2W 14.1N 50.8W 15.6N 57.0W

BAMM 12.1N 38.6W 12.0N 45.5W 13.1N 50.4W 16.1N 56.0W

LBAR 12.8N 38.3W 13.2N 47.0W 13.8N 51.3W .0N .0W

SHIP 59KTS 78KTS 89KTS 98KTS

DSHP 59KTS 78KTS 89KTS 98KTS



...INITIAL CONDITIONS...

LATCUR = 11.7N LONCUR = 25.0W DIRCUR = 275DEG SPDCUR = 8KT

LATM12 = 11.6N LONM12 = 23.2W DIRM12 = 270DEG SPDM12 = 7KT

LATM24 = 11.5N LONM24 = 21.9W

WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 25KT

CENPRS = 1008MB OUTPRS = 1012MB OUTRAD = 200NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN
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Looking at the vorticity for 90L, seems to be pretty even between 850/700mb. At 500mb, vorticity seems to be lining up pretty well with the western edge of the 850/700.....*shrugs again*

Also of note, ex-TD2 still has good vorticity and remains stacked 850-500mb. With better conditions to the west, I'm not so sure that I'm ready to call it dead in terms of a little redevelopment.
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Quoting victoria780:
You could be right ,I was in a hurry.However this model for a long time showed it going up the east coast..Much further west now..


No problem. :) I noticed that too. "TX/LA"
makes me sit up and take notice. Lol. Better than an alarm clock. We're a little jumpy round here. But I agree. I would feel a lot better for everyone if all the models kept taking it out to sea. I'm not quite at the nail biting stage. But I'll probably need to borrow someone elses by next week. Lol
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Quoting jipmg:


exactly, a larger storm would be a very dangerous one, could you imagine the amount of damage Andrew would have caused had it been the size of Katrina if it hit SFLA? We'd get tropical storm force gusts all the way up through central florida.


Thanks guys, good info. I agree that the size and movement speed is important.

I am surpirsed at the ratio given by NHC...100 times?

Maybe, Dr.Masters could be requested to explain this a bit further at some point?

Dr.Masters, would you mind doing an article on this sometime, unless you already have and post the link?

Thank you.
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3347. palmpt
The o-o-o is not for long...
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90l will pound puerto rico with southern edge of storm
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3345. Skyepony (Mod)
West wind on the east end of cuba, just popped up south of that blob. Nowcoast
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3344. palmpt
Crown Weather had good reasoning on the Gulf possibility this morning... I'm not one of the Gulf freak-out folks, but I am in a position that causing me to be very focused on the possibilities. We have said this a 1,000 times on this blog, if a Cat 3 gets into the gulf this year heading North... it will be a very bad outcome. Oil prices and, here is the one that does not get enough attention, insurance affordability and availability become even bigger issues. And as always, there is too much national clutter right now to solve that one. Insurance companies literally control every aspect of that discussion. Want to put the economy on steroids, especially near coastal areas where 50% of the population lives: solve that problem. Anyway, let's hope nothing gets in the Gulf... or hits any other U.S. coastline for that matter.
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Can't get excited over TD2 until it fires thunderstorms over its centre. It does have a good structure, sure.

I'm somewhat surprised they kept it at orange.

Member Since: August 23, 2008 Posts: 7 Comments: 5300
Looks like 90L's circulation is even more elongated than it was yesterday.
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The scary part for Florida is that if it follows the models it could miss all the big islands that would weaken it potentially bringing it into Florida or Carolina a lot stronger than it would be if it went over PR or DR. Most of the models are making me think it could go just north of all the islands.
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Morning all.
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Quoting Stormchaser2007:
Close to the edge.


Like Dean '07. That anti-cyclone will help some.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting homelesswanderer:


Do you have a link to that? Mine shows New Orleans. Thanks.
You could be right ,I was in a hurry.However this model for a long time showed it going up the east coast..Much further west now..
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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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