Disturbance 90L close to tropical depression strength; TD 2 may rise again

By: Dr. Jeff Masters , 2:02 PM GMT on August 14, 2009

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A strong tropical wave (90L), with a large circulation and a moderate amount of heavy thunderstorm activity, is a few hundred miles southwest of the Cape Verdes Islands, off the coast of Africa. This morning's QuikSCAT pass shows that 90L has a large circulation, but this circulation is not yet well-formed, as it is elongated along an east-west axis. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are gradually becoming better organized, with some spiral banding evident on the south side of the storm. Satellite intensity estimates from NOAA already put 90L at tropical depression strength with 30 mph winds, but the storm does not yet have a well enough formed circulation to be classified as a depression. 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 was. However, there is some dry air from the SAL being sucked into the circulation of 90L, and this is retarding its development.

Wind shear is moderate, about 10 - 15 knots, but is forecast to fall to the low range, 5 - 10 knots, later today. Shear is then forecast to remain low for the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow 90L to develop into a tropical depression by Saturday, and potentially reach hurricane strength by Wednesday. Most of our reliable models strengthen 90L into a hurricane by Wednesday, when the storm is expected to be near the northern Lesser Antilles Islands. One important outlier is the ECMWF model, which has 90L passing to the north of the islands, and eventually recurving out to sea east of Bermuda. The ECMWF was by far the most reliable model for forecasting hurricane tracks last year. However, all of our models are pretty unreliable going out 5 days in advance for systems that have yet to reach tropical depression strength. Once 90L becomes a tropical depression and develops a well-formed circulation, the models will have a better handle on forecasting where it will go.


Figure 1. The remnants of Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

Tropical Depression Two may come back
Tropical Depression Two died yesterday, but may rise again. Satellite loops of the remnants of the storm show that heavy thunderstorms are again attempting a comeback near the axis of what is now a tropical wave. However, dry air continues to interfere with the development of the thunderstorm activity, and moderately high wind shear of 15 - 20 knots is also inhibiting the process. Wind shear over the remnants of TD 2 is expected to remain in the moderate range, 10 - 20 knots, over the next four days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C two days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to the north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that any re-development of the storm will be slow to occur. NHC has given the system a medium (30 - 50% chance) of becoming a tropical depression again by Sunday morning. Only one reliable model, the NOGAPS, is predicting regeneration of TD 2. The NOAA Hurricane Hunters are flying research missions into the remnants of TD 2 today and Saturday.

I'll have an update Saturday morning, or earlier, if significant developments occur.

Jeff Masters

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Quoting atmoaggie:

But how many of them are useful?


I think models are usefull when they agree on a forrescast like 90L one, always have the error marging but they are a good guidance in short term (120 hrs).
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Of course...they could issue one now and say its the 5 am advisory.
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Nole? Did you look at the NAM that's coming out now? Looks like a little something headed up toward MS that should kick up a bit of surf
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What are the latest models doing?
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JFV is in charge of posting the updates on the NHC website. He is kicking back and laughing is A@& off ! JK
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Quoting jipmg:


how the heck is this not a dreppsion yet? Not only that but TD 2 had a pressure reading of 1007, and winds sustained around 30mph.. with impressive convection.

Someone needs to contact NHC!


I'm sure they know what they're doing...
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Well my heart rate is up the NHC forgot how to upgrade systems i need a break and a drink lol...I know that 02L is now TD2 i don't know what the flip they doing....see ya later fellas and ladies
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting antonio28:
Well no upgrade, 00z models runs comming up next! I going to wait until 2am.

Still at the analysis phase: http://www.nco.ncep.noaa.gov/pmb/nwprod/prodstat_new/prdst_00_UTC_GFS.html
Member Since: August 16, 2007 Posts: 6 Comments: 12461
3275. IKE
Quoting Patrap:
..You dont think WS took the NHC Hostage and is Typing the 11pm ,..and that's why its Late..?




With a 2 mile wide cone aimed right at his trailer....from 2,000 miles away.
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3274. Patrap
Member Since: July 3, 2005 Posts: 424 Comments: 128259
Quoting Weather456:


ya bet cha
same here im going to watch this till 2
3271. jipmg
Quoting Hhunter:


how the heck is this not a dreppsion yet? Not only that but TD 2 had a pressure reading of 1007, and winds sustained around 30mph.. with impressive convection.

Someone needs to contact NHC!
there's always tomorrow since it didn't happen @ this advisory.
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Quoting atmoaggie:

But how many of them are useful?


Maybe 200.
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Quoting CaicosRetiredSailor:
If we're going to be here until 5am.

I am going to open a "drinks" stand right next to the pitchfork/torch guy.

CRS


I'll be open all night!
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Will one of you please call the NHC and wake them up?!?!?!
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Quoting louisianaboy444:
So if they don't come out with anything that means nothng is classified?


Unless a special advisory is issued then yes. However recently the NHC kinda seems to like initiating advisories on a system whenever they want.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Good ole' conservative NHC...
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Quoting antonio28:
Well no upgrade, 00z models runs comming up next! I going to wait until 2am.


ya bet cha
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting louisianaboy444:
So if they don't come out with anything that means nothng is classified?


That's my take. I don't think we have anything classified. Maybe at 2 AM.
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Waiting for wetting rains coming from disturbance north of Cuba, keep chuggin baby
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Quoting antonio28:
I think we are going to break the post record in this blog 3200 post and counting.

But how many of them are useful?
Member Since: August 16, 2007 Posts: 6 Comments: 12461
3259. Patrap
..You dont think WS took the NHC Hostage and is Typing the 11pm ,..and that's why its Late..?


Member Since: July 3, 2005 Posts: 424 Comments: 128259
Quoting louisianaboy444:
So if they don't come out with anything that means nothng is classified?


That's the way I'm looking at it.

Onto the 5am advisory.
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What great entertainment tonight!! Watching Camille on The Weather Channel. Technology has changed in 40 years!! All we had back then was an AM Radio after we lost power. It was hard to get any info that night.
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Im here in an a leather arm chair layed back, with glass of Dom Perinon, chillin.
90L is looking good 2night
Member Since: July 24, 2005 Posts: 407 Comments: 19076
now I have the shakes.....never laughed so hard reading blogs!!!
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3253. trey33
Quoting IKE:


Putting up shutters.


lol!
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So if they don't come out with anything that means nothng is classified?
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting tiggeriffic:
just sittin back watchin everone freak out... i swear the room is full of jfv's under different handles at this point...


I just spit my drink all over my expensive monitor......ROFLMAO
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Quoting CaicosRetiredSailor:
If we're going to bee here until 5am.

I am going to open a "drinks" stand right next to the pitchfork/torch guy.

CRS
Jack and Coke for me please CRS
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CRS -

My brother was in Providenciales as well.. not sure what section. He worked for a dive shop as a dive master. His favorite place in the world!
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Quoting DestinJeff:


voicemail message:

"To leave a call-back number, press F5"


lol lol
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Next outlook is 2am,every 5 hours.Last was 8pm.No 11pm advisory.
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Well no upgrade, 00z models runs comming up next! I going to wait until 2am.
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Quoting extreme236:


Try ALT F4, it works better.

Oh, yes, please do. And keep pressing it. (not directed at you, ex)
Member Since: August 16, 2007 Posts: 6 Comments: 12461
3243. Hhunter
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baja...looks like the best day will be sunday morning...surfmom should be getting something maybe in the morning...depending on the winds...
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What's going on?
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Well I see we're all being driven insane in here o_O
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3239. hahaguy
Quoting Weather456:
Wow, this was the best/funniest blog secession in a long time. No drama or arguments, just good ole comedy.


I think this is what we all needed.
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hell i just fixed me a Margarita.....came back and Sammy still has not posted our update....SAmmy you better get your act together here real soon.....or the Indians are getting very restless...DO U HERE ME!
Member Since: September 2, 2007 Posts: 178 Comments: 20439
just sittin back watchin everone freak out... i swear the room is full of jfv's under different handles at this point...
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Quoting canesrule1:
agreed, maybe around two am, im gonna be on till its a TD!!!! who is with me????


That's it, I give up till 5am.
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Ike!
Special Ward for the Weather Nuts!
Quoting IKE:
NHC probably designates first named storm of the Atlantic season on December 1st, 2009.

456 WU bloggers are in the mental ward from pressing F5 key for 6 months, hoping, against hope.



Watch it on ESPN.
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Quoting RufusBaker:
I have the phone number to the NHC anybody wanna call???
me

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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.