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 Orcasystems:


Its a new one... BeachFoxx and Surfmom got it for me at Christmas :)


now thats funny!
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Quoting Drakoen:


Those aren't ensembles they are the dynamic models.



The consistency kind of reminds me of Dean... of course they were slightly wrong with Dean in the end, although they did get the intensification correct.
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it isn't fair...everytime a storm is headed toward PR...my ex is on the west coast of the usa...
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Member Since: March 19, 2009 Posts: 0 Comments: 1421
So what do these models look like besides a cluster ****?
Please watch the Darth Vader Imperial March video (above).
"Entertaining and relevant," I heard one critic say.
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2631. Patrap
If 90L can be all she can in a weeks time, TD 2 will be a Faded memory Lost to well,.Calamity downstream after
Member Since: July 3, 2005 Posts: 426 Comments: 129093
Quoting Patrap:
Drak,that ensemble cluster grouping is as good as a Marine Riflemans Target on the 200 Slow Fire Dog Target.

WoW..Impressive consistency for so far out


Rare to see such tight clustering in the ensembles 96 hours out.
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2629. KEEPEROFTHEGATE (Mod)
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Whe you doubt what can happen to a dead storm just think "Karen" wow that was a fun one to watch. I think she finally ended up in Hawaii
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Quoting Funkadelic:


Hey Drak, great observation.. I have noticed that too. Even though this thing is far away models seem to have a good grip on the direction it will be moving.

All I know Is that I live in West Palm Beach, and this weekend I will be buying a fex extra cases of water just in case:)


If this went to West Palm you'd need a whole lot more than a few cases of water
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Quoting rareaire:
howdy tigger! Seems like old home week on here except I dont remember Orca's halo being that shiny!!


Its a new one... BeachFoxx and Surfmom got it for me at Christmas :)
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Quoting BiloxiGirl:


I just saw the same thing and had the same thoughts. And now with such tropical activity my nerves are starting to get a little edgey.
Amen sister Amen...never ready for one but deifnietly not ready now..still too fresh in the mind
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Quoting Drakoen:
Once this thing gets going its really going to get going.


Did any models pick up the trof during this recent model run?
Member Since: May 17, 2009 Posts: 0 Comments: 559
Quoting Drakoen:
Another look at the models which are tightly clustered:


Doesn't look too good for the Leewards and Puerto Rico.
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Quoting reedzone:


A recurvature is possible, but west of 60W.. high pressure is too strong to recurve it before passing Bermuda. that model guidance shows how strong that ridge really is.
so that would mean a track more towards se fla?
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2620. Drakoen
Quoting Patrap:
Drak,that ensemble cluster grouping is as good as a Marine Riflemans Target on the 200 Slow Fire Dog Target.

WoW..Impressive consistency for so far out


Those aren't ensembles they are the dynamic models.
Member Since: October 28, 2006 Posts: 57 Comments: 30617
lol rare...look real close and you can see the horns holding up that halo!
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2618. HadesGodWyvern (Mod)
Japan Meteorological Agency

Tropical Disturbance Summary (0000z 14AUG)
=========================================
SUBJECT: Tropical Depression In Sea East of Marshalls Island

At 9:00 AM JST, Tropical Depression, Former Maka (1008 hPa) located at 13.6N 177.8E has 10 minute sustained winds of 30 knots with gusts of 50 knots. The depression is reported as moving west slowly
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Tightly clustered models sounds ominous.
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tampaspin...this might be one of those sneaker storm ....just might catch everyone off guard that don't normaly watch these things....
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2615. szqrn1
DRAK...how do you get to that image from that website.. I am fishing around on it
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Quoting KATRINABILOXIGIRL:
Local news showing the first images form the local news station reporters just hours after Katrina..wow..feels just like it was yesterday..such sad memories


I just saw the same thing and had the same thoughts. And now with such tropical activity my nerves are starting to get a little edgey.
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hurricane country here too Funk...I start in June and buy a little bit extra every week... if i don't use it...I put all the canned stuff in the food drives they have at the holidays after the season is over
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2612. Patrap
Drak,that ensemble cluster grouping is as good as a Marine Riflemans Target on the 200 Slow Fire Dog Target.

WoW..Impressive consistency for so far out
Member Since: July 3, 2005 Posts: 426 Comments: 129093
howdy tigger! Seems like old home week on here except I dont remember Orca's halo being that shiny!!
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Quoting Drakoen:
Another look at the models which are tightly clustered:


A recurvature is possible, but west of 60W.. high pressure is too strong to recurve it before passing Bermuda. that model guidance shows how strong that ridge really is.
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Kman, don't you agree that TD2 got rid of a lot of moisture making cyclogenesis more conducive for 90L? Also, SAL is low in front of 90L last I checked and if shear stays in check SSTs should begin to warm, making it easy for a remnant low to regenerate.
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2608. Drakoen
Once this thing gets going its really going to get going.
Member Since: October 28, 2006 Posts: 57 Comments: 30617
The Bahamas disturbance is influenced by an ULL near the Eastern Tip of Cuba.....Looking at the 850 and 550mb vorticity...a low might be trying to make it to the surface...the ULL could help in venting a Low. It also has a nice Divergence return. This does bare some watching.
Member Since: September 2, 2007 Posts: 179 Comments: 20448
well guys looking at this ex-TD2 has got some what stronger look at MSLP
Link
Link
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2604. Drakoen
Another look at the models which are tightly clustered:
Member Since: October 28, 2006 Posts: 57 Comments: 30617
Quoting Chicklit:

She's ugly enough to be intelligent looking.

.
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hiya rare
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Quoting hunkerdown:
intelligent looking ????

She's ugly enough to be intelligent looking.
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Quoting TampaSpin:


NO your 100% correct....most storms that far north never make it into the Caribbean....i just think now the remanat low will have a good chance to go south of Pureto Rico.


That could still happen if it stays weak like it is and if so watch out once it passes 70W
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2599. Drakoen
Quoting szqrn1:
DRAK.. you have links to share of that image and GOM?

Link
Member Since: October 28, 2006 Posts: 57 Comments: 30617
Quoting rareaire:
EVENING ALL!!


OMG, another old timer
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2597. Drakoen
GFDL and GFS ensemble mean are the fastest with the system.
Member Since: October 28, 2006 Posts: 57 Comments: 30617
Quoting popartpete:
Greta got her start with the Kennedy kid trial.


I thought it was the OJ trial ?
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2595. szqrn1
DRAK.. you have links to share of that image and GOM?
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EVENING ALL!!
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Quoting tiggeriffic:
hey orca...looks like not much has changed since last year...roflmao...


Not much... a few have changed their nicks to protect the guilty.. but its basically the same as it was last year.. more good stuff then bad :)
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2592. Skyepony (Mod)


The wave & ULL are nearly on top of each other, lower vorticity picking up. This afternoon it had no mid level vorticity, now has a little. Impeeded by shear for now. 10-20kts~ That usually allows slow development if at all. Also lost it's anticyclone today. A few thing that may have it looking better than most faced with that shear, it's being fanned pretty well from the top..excellent diffluence & feeding off some daytime island heat.
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2591. Drakoen
Tight dynamic model cluster:
Member Since: October 28, 2006 Posts: 57 Comments: 30617
Quoting kmanislander:


Had to pull your chain LOL

Well, if it does not regenerate I would expect the remnant low to dissipate before having a chance to enter the Caribbean. If it does regenerate then my thinking would still be for a pass to the N of the Islands.

Either way I stand by my thinking that it started too far N and too far East to enter the basin.Ironically, having started as far N as it did resulted in all the dry air and low SST that caused it to weaken and move further W than forecasted. Now there you have a twist for the books eh ?


NO your 100% correct....most storms that far north never make it into the Caribbean....i just think now the remanat low will have a good chance to go south of Pureto Rico.
Member Since: September 2, 2007 Posts: 179 Comments: 20448
Quoting Chicklit:
Greta Van Sustren is a disappointment.
She is an intelligent looking woman, albeit a weird-looking one, that looks like she will say something and then says nothing at all.
Greta got her start with the Kennedy kid trial.
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2588. Drakoen
Member Since: October 28, 2006 Posts: 57 Comments: 30617
hey orca...looks like not much has changed since last year...roflmao...
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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.