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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I think the blog about to go poof
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Baja! Ike!! and everyone....
This is great entertainment!
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(((( Tig !!! )))) Wow! Everyone's ocming in tonight!!
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3130. GatorWX
Quoting mobilegirl81:

GO REBELS!!


Yea!!!!!, you had a great season last year,congrats! I hope your the team we have to beat in the SEC tournament! It would be a bit refreshing to see a new face.
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3129. jipmg
great the NHC didn't upgrade anything
Are the advisories ever late?
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starting to look like no new or renamed TD @ 11pm.
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Quoting MississippiWx:
Pretty sure a couple of the guys issuing the advisories at the NHC are watching this blog, laughing their a$$es off at some of you guys.
would not be suprised LOL
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ANGRY MOB stand is OPEN for Pillaging!
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Dear lord people. You all (with the exception of a select few) are acting like little kids in a candy store. Calm down and give the NHC some time.
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11:01 pm...nothing!

LOL!!!!
Member Since: July 31, 2006 Posts: 56 Comments: 8112
3122. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
3120. viman
Advisories are issued at 5am/pm and 11am/pm -- the experimental stuff is issued at 2am/pm and 8am/pm -- Special advisories can be issued at anytime to initialize a system.
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3119. trey33
It's 11....
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((((((( Beachy!!! ))))))
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Sammy your gonna give people a heart attack thinking that was 02L
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting canesrule1:
ROFLMAO!!!!!!!!!!!!!!!HAHAHAHA!!!!!!!!LMAO!!!!!!!LOL
Its not that funny.......
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11PM,

9 deaths already reported
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Can anyone update on 90L I've been at work most of the day...Thanks :)
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hiya zoo, tampa, patrap, and any one else I missed...waiting for keeper to show up...they only open the gates during hurricane season ya know...only gives him a few months outta...well...you know where :)
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3112. 7544
Quoting canesrule1:
i guess no TD at 11, whatever.


the longer it takes it could be now
Member Since: May 6, 2007 Posts: 0 Comments: 6874
Quoting StormW:


So much for an anticyclone.
Member Since: June 9, 2007 Posts: 4 Comments: 15950
LMAO Ike!!!!!!!!!!!!
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Secretly inside closed doors in the National Hurricane Center:

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Ummm...if anyone cares about fish storms:

HURRICANE GUILLERMO ADVISORY NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP102009
800 PM PDT FRI AUG 14 2009

...GUILLERMO MAINTAINING ITS STRENGTH...

AT 800 PM PDT...0300 UTC...THE CENTER OF HURRICANE GUILLERMO WAS
LOCATED NEAR LATITUDE 18.3 NORTH...LONGITUDE 130.3 WEST OR ABOUT
1355 MILES...2180 KM...WEST OF THE SOUTHERN TIP OF BAJA CALIFORNIA.

GUILLERMO IS MOVING TOWARD THE WEST-NORTHWEST NEAR 16 MPH...26 KM/HR
...AND THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 TO 48
HOURS.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 100 MPH...160 KM/HR...WITH
HIGHER GUSTS. GRADUAL WEAKENING IS FORECAST TO BEGIN SATURDAY AS
GUILLERMO MOVES OVER COOLER WATERS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES...45 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 120
MILES...195 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 976 MB...28.82 INCHES.

...SUMMARY OF 800 PM PDT INFORMATION...
LOCATION...18.3N 130.3W
MAXIMUM SUSTAINED WINDS...100 MPH
PRESENT MOVEMENT...WEST-NORTHWEST OR 285 DEGREES AT 16 MPH
MINIMUM CENTRAL PRESSURE...976 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
200 AM PDT.

$$
FORECASTER KIMBERLAIN/AVILA
Member Since: July 31, 2006 Posts: 56 Comments: 8112
What if its late? Gasp!
Member Since: August 2, 2007 Posts: 19 Comments: 19234
sorry its 11,its over
Someone please slam that #*%& Door!!!

3089. CycloneOz 9:58 PM CDT on August 14, 2009 Hide this comment.

Quoting IKE:



OMG, look at those tracks.

Man, the GoM worked so well closed for those great weeks in July.

These two freaks may walk right in the front door now!
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Pretty sure a couple of the guys issuing the advisories at the NHC are watching this blog, laughing their a$$es off at some of you guys.
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Quoting CycloneOz:


...and a believe that came again in 2004 when Hurricane Ivan struck.

....and Elena, and Erin, and Opal, and Dennis, and we were sure - Katrina before the forecast changed that morning 9not to mention others between them and the pre-recorded storms.
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That really had me laughing
This is crazy..lol
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I'm pouring the milk.
If I miss the 11 TWO by a minute I think I can handle it.
It's not exactly like these clouds are on our doorstep. I'm not exactly sure what difference a call makes 10 days out.
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Harry Carey!!!!
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Quoting Patrap:



.."Go Ahead Blogger,your on the AIR..!..do you have the 11pm for Us here in Wunderland" ..?



lol lol stop it, my sides are splitting
Member Since: July 24, 2005 Posts: 407 Comments: 19076
i guess no TD at 11, whatever.
I am already smoke a packege of cigarate! Waiting...
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....um

what's the price on the pitchforks?

CRS
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3091. IKE
***NHC poker tourney at 11***

webcam links.....standby.....
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Hmm maybe another miscalculation, no TD at 11 p.m. tonight.. Oh well, Definitely 2 TDs by tomorrow. Maybe even Ana and Bill by tomorrow night at this time. We shall see...
Member Since: July 1, 2008 Posts: 13 Comments: 7437
I'm not surprised that there isn't a depression the NHC is always hesitant. But if there isn't a td or two tomorrow I'll eat crow or something like that
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Quoting Patrap:



.."Go Ahead Blogger,your on the AIR..!..do you have the 11pm for Us here in Wunderland" ..?

ROFL!!!!!!!!!!!!!!
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MY EYE IS TWITCHING THIS IS TORTURE
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And now Beachie, the gals are back! Where is Surfmom?
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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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