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 Nolehead:
geeez!!! i can't stand TWC, so much for the tropical at 50 before the hour...it's either the damn "oh it could happen now" or "storm stories"......I want my TWC2....


HEAD ON....."Apply directly to the forhead"
Agreed. John Hope is probably rolling over in his grave.
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1236. cg2916
Hey guys, I'm back again. I'm refreshing the NHC site every few seconds for the advisory.
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The models sure are liking 90L now and they aren't pulling it North anymore.

I give a 60% chance that doubtcasters send this back north before I finish typing this.
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1233. Buhdog
I think we have officially jumped the shark
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1232. IKE
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1230. HadesGodWyvern (Mod)
Mauritius Meteorological Services

SHALLOW LOW NEAR 07S 84E

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Looks like we gonna have us a ruutin. 112miphs is cookin'

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Quoting caneluver:


Not Good
Based on this map, I feel it is something the ne conus should stay alert of. Hopefully, it will be nothing. I'd hate to lose my oceanview condo to a 'cane!
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Patrap...thanks for the video on hot towers. very informative
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Hey guys. looks like things are starting to pick up. I just hope the storms can wait to destroy my house until I get back home from Wyoming on Friday. If Hurricane Zelphia wipes out my house on Thursday I will not be happy

Heres to another semester of school, another season of wishcasting, and GO NOLES!
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1224. KEEPEROFTHEGATE (Mod)
Quoting WeatherStudent:
I was only joking all; anyways, the normal JFV is back, so, what's up, y'all?
farfromnormal
Member Since: July 15, 2006 Posts: 171 Comments: 53838
Quoting CaneWarning:


Two funnae!


Noe wai...i thut u had past the grammer and speling prothithiencie tesst?
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Quoting jurakantaino:

You could use a better language ,plus before the U.S. not sure if you know there are about 50 island nations that the CV storms usually affect first.
That is a real old comment and you are not adding anything to the current flow of the blog.

PS-Why do ppl quote the contents of 'offensive' posts? It
seems counterproductive.

(edit-Go ahead with the "hypocrite" flames, I read my comment and want to flame myself.)
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Quoting CaneWarning:


Two funnae!


LOL Jenn-eye
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Quoting IKE:


Dsicuont teh ECMFW?

No wiegh!
I def don't think ecmwf is right,look at my blog link i posted and expected tracks based on majority of models.
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1217. IKE
Quoting TheCaneWhisperer:


I think all were so concerned about 90L going out to see that they didn't see TD2 impacting south florida and into the GOM


TD2 looks to have a better shot of getting into the GOM vs. 90L.
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1216. HadesGodWyvern (Mod)
Vortex that is correct
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Quoting CaneWarning:


ehllo WSster how rae yuo todae? Watt do yuo thikn aboot htis stmor? Is hte hting gonig two nrut?

LOL !!!
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Quoting IKE:


Dsicuont teh ECMFW?

No wiegh!


Two funnae!
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Quoting jasoniscoolman10:
09L IS 3,000 MILES WAYS FOR THE USA U PEOLPE DO NOT KNOW SHIT WHERE THIS STORM IS GOING IN 7 DAYS FROM NOW..I BET YOU ITS NOT GOING TO BE A FISH STORM LETS TALK ABOUT SOMETHING ELSE..STOP TALKING ABOUT 90L BEING A FISH STORM ITS SILLY TALK TO ME. U ARE WAITING TIME Talking ABOUT FISH STORM WHEN THE STORM IS SO FAR ALLWAY FROM THE USA...

You could use a better language ,plus before the U.S. not sure if you know there are about 50 island nations that the CV storms usually affect first.
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1212. IKE
Quoting Patrap:



WS told us to discount that un IKE...


Dsicuont teh ECMFW?

No wiegh!
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Quoting Vortex95:
TCFA is Tropical Cyclone Formation Alert correct?


Yes.
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Quoting Patrap:



WS told us to discount that un IKE...


Yep.
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Quoting IKE:
Looks like the 12Z ECMWF puts TD2 in the northern GOM on the end of it's run.

Not sure if anyone posted that.


I think all were so concerned about 90L going out to sea that they didn't see TD2 impacting south florida and into the GOM
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Is the blob above Hispaniola tropical in nature?
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1206. Patrap
Quoting IKE:
Looks like the 12Z ECMWF puts TD2 in the northern GOM on the end of it's run.

Not sure if anyone posted that.



WS told us to discount that un IKE...
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Quoting rwdobson:


YOUR pretty smart chicklit...:-)

heh heh, your for you're is one of my favorite internet typos.

although "no thrat" from yesterday made me laugh too.

i try not to think about it.
even misuse punctuation occasionally!
wow. freedom is great, huh?
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Link Again my blog just posted on both systems.
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90L looks pretty nice for being so large. I see that some models now take this a bit more north than before. similar to the way they did with Dean in 2007. Should have a TD later tomorrow or Saturday.
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Quoting IKE:
Looks like the 12Z ECMWF puts TD2 in the northern GOM on the end of it's run.

Not sure if anyone posted that.


I was wondering when someone was going to notice that.
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1201. Patrap
Official NAVY Tropical Page without security Wall
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Quoting Patrap:
.."Well,the Human named JFV on the wunderground said FEMA could Help us relocate ,..

and No,..I dont have any ID on me Now,..its on the er,..ship parked over Dakar pumping the SAL into the Atlantic"..



This picture is so funny....especially with the "quotes" :)
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Good afternoon,

With the tropics heating up; we want to let everyone know that the Portlight Disaster Relief featured blog is now open for comments, and we have provided and update on our response plan in the event of a land falling hurricane.
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1198. IKE
Looks like the 12Z ECMWF puts TD2 in the northern GOM on the end of it's run.

Not sure if anyone posted that.
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Quoting Prgal:


Alright! So that means that by Sunday we should have a high probability that whatever the models are showing at the moments is right. I shouldnt be so worried today...just wait until Saturday or Sunday. Thank you!
I would also not think of the models as EVER being right. Hurr Charley, for ex. Just think of them as gradually getting more believable as the forecast lead time decreases.
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It looks like the out flow from 90L is shearing the convection from TD2 out to the NW!
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Updated readings from bouy at 12N 23W

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1194. fire635
Quoting Chicklit:

You'll drive yourself crazy with that.
Just pretend it isn't happening.
I'm a certified English teacher and blog.
You cannot have it 'your way' here.
Or should I say, "ur?"


lol... thanks. I really have been holding it in for quite some time.
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Keeper,how about just posting links to the Navy stuff, since it seems to have security cert. problems...
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Terra Nova: Excellent update - thanks!
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Quoting CaneWarning:


ehllo WSster how rae yuo todae? Watt do yuo thikn aboot htis stmor? Is hte hting gonig two nrut?


No he didn't! lol Back to lurking.
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Quoting StormBeast:
jasoniscoolman10,

I must tell you that am SHOCKED by such immature, and poor grammatical posting. If one were to guess anything about you, based on the pic you provided.. it would say "Jason clearly has his life together. He is well educated, and doesn't live in his mother's trailer" Now perhaps you just had a bad day at your law firm, or your trophy wife overspent on your black AMEX card....

.. just let's get back to being the REAL, TRUE, Jason... that so transparently is you.
Can't we all...just get along???
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Quoting rwdobson:
The thing is, small differences in the track now (compared to the models) then lead to large differences in the track later. I mean, we don't even know where the center of 90L will be when/if it becomes a TD or TS.


Exactly, a 100 mile difference now can mean a 500 mile difference down the road. Or, just far / close enough to a trough that will re-curve it. The possibilities are in the hundreds of thousands right 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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