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 Acemmett90:

37 knots how fast is that

Around 42.5 mph
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136. 7544
Quoting canesrule1:
I anticipate this will be a tough cookie! this reminds me of Andrew sooo much because its the same time of year, it's an A storm, its going to develop close to Africa and its anticipated to make landfall on the Eastern seaboard, Dèjà Vu!


10 day gfsx you be the judge pretty close

Link
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Quoting Acemmett90:

thats ts strangh
yup
Quoting CaneWarning:
It looks like 90L has a closed low...
It's closed but brod which usually means a large storm.
Thank You K Man
So, north of the DR: it is an ULL, with convergence with the wave, OK. so not expected to drop down at this time. Those types of flare ups just catch one's attention when they are close to home.
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It looks like 90L has a closed low...
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting Drakoen:
SHIPS takes 90L to hurricane strength
I anticipate this will be a tough cookie! this reminds me of Andrew sooo much because its the same time of year, it's an A storm, its going to develop close to Africa and its anticipated to make landfall on the Eastern seaboard, Dèjà Vu!
Thanks, Dr. Masters.

Guillermo RAPIDLY strengthening


GFDL Model Run for Guillermo:


**GFDL model run keeps it a TS not turning it into a hurricane**
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126. 7544
Quoting StormW:


Yes, it's in synopsis.


thanks storm looks like whatever the wave at 65w does will bring rain and windy conditions over so fla on sat of this week acording to local mets
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Quoting weatherwatcher12:
Invest 90L:

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Quoting sctonya:
Does anyone think we can sneak in at least 1 or 2 more days of 0,0,0?


Im thinking those 0,0,0 days are numbered... we might make it through the next 24-48 hours... but not thinking very likely after that
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If you look at the quickscat, the circulation itself is closed and not broad, the convection around it however is broad and needs to fill in closer to the center.
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I think this quikscat of 90L looks better.
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Quoting kmanislander:
The flare up to the N of the DR is a tropical wave interacting with a ULL immediately to the West of it. This is creating a diffluent environment resulting in the flare up of showers.

There is a very low chance of development here.



Yeah. The wave has pretty much split into two. The northerly piece is interacting with the Upper Level Low which is causing the increased deep convection. The shear is too high for right now for development. This piece may need to be watched when it gets into the Gulf, but for now it's no threat.

The southern half of the wave very near South America in the eastern Caribbean looks a bit more promising for development in the next 24-48 hours. Shear here is less as it's farther from the Upper Level Low. Have to keep an eye on this through the day...
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Quoting Acemmett90:

37 knots how fast is that
around 41MPH
Quoting KEEPEROFTHEGATE:
apocalyps

you are about to be replaced with empty space just like whats in your head


KOTG... I already used the power that was vested in me by the bog authority to make him go poof from my eyes... #5..
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116. srada
Quoting StormW:
TROPICAL WEATHER SYNOPSIS /TD2/INVEST 90L/SYNOPSIS AUG 13, 2009 ISSUED 10:40 A.M. EDT


Good Morning everyone! Great Analysis StormW..I have a question in reference to SEUS..this trough that is forecasted, when is this supposed to happen and would it play a part in TD2 path (if it develops)?
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SHIPS takes 90L to hurricane strength
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Does anyone think we can sneak in at least 1 or 2 more days of 0,0,0?
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Quoting KEEPEROFTHEGATE:
apocalyps

you are about to be replaced with empty space just like whats in your head
lol, don't fight with him because u could end up banned, and we don't want such a good blogger to be banned.
Quoting StormW:
Good morning!

Thanks for the update Dr. Masters

TROPICAL WEATHER SYNOPSIS /TD2/INVEST 90L/SYNOPSIS AUG 13, 2009 ISSUED 10:40 A.M. EDT


Thanks Storm for your update...I am going to watch 90L very closely.
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Invest 90L:
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Has anybody seen cyclonebuster lately.


Mystery deepens over missing ship
The Arctic Sea

Russian navy ships are hunting in the Atlantic for a 4,000-tonne cargo ship that vanished more than two weeks ago, triggering an international mystery.

Observers have suggested the ship was hijacked,

Carrying timber reportedly worth $1.8m (£1.1m), it sailed from Finland and had been scheduled to dock in the Algerian port of Bejaia on 4 August.

------------------------------------

...you don't suppose he got some "backers" and built some big wooden tunnels out there off Africa?

heh heh

CRS
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Quoting KEEPEROFTHEGATE:
apocalyps

you are about to be replaced with empty space just like whats in your head

hahahaha that giving him to much credit
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wave east of the Bahama islands firing this morning
Member Since: September 5, 2007 Posts: 0 Comments: 3488
The OFCL/NHC forecast track has so far been the most accurate with TD2, the least accurate core model has been the LBAR. Model Performance Statistics for AL022009.
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Quoting Acemmett90:

this is not a time to start panic so im reporting you and ignoring you

I have done the same
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apocalyps

you are about to be replaced with empty space just like whats in your head
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Alright guy's I made an update. This is my first one of the season so bare with me. Tell me what you think!
90L: The one to watch
Member Since: August 10, 2009 Posts: 3 Comments: 672
WV loop showing Twave interacting with the ULL North of Haiti
Member Since: August 19, 2006 Posts: 0 Comments: 15842
Quoting Acemmett90:

this is not a time to start panic so im reporting you and ignoring you
i already did
looking impressive, imo:
Got a feeling TD2 could be one these systems that jumps up and bite you in back when you least expect it, well worth watching imo
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Quoting Buhdog:
I was the first to board my house for Charley in Cape Coral in my hood (wed)...and it was almost this time exactly when he went thru rapid intensification! It was the calm before the storm on that friday the 13th and I was not caught off guard albeit a generator...and i am not afraid of what this season brings. Once you have been thru it...then it really becomes a matter of being prepared for the worst and hope for the best. The anxiety will not be as much of a problem knowing my house can take 110mph.. anything bigger and i am out.


I have a friend in Punta Gorda who lost everything. He stayed thinking the storm was headed to Tampa.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting largeeyes:
looks closed, though elongated....


Agreed. The Quikscat showed that well.

Good convergence in the band to the north and to the south, but little if any on the eastern and western sides.

I was a little agressive yesterday in my forecast when it appeared from the TPW loop that all the moisture was streaming towards one point. Crow for me... Slow development should continue and we could see a depression anytime in the next 36 hours.

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Quoting Acemmett90:

stop fear mongering

Dont feed him, just ignore him and if nobody pays attention to what he says he will stop :-)
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Quoting wunderkidcayman:
I think if TD2 keep blowing up convection we will see a stronger TD2 and maybe a TS later on
prob on fri or sat
Link
doubt it, 90L is the one to be watched, that could be the seasons first hurricane, looks like the "Bill wave" should be named the "Ana" wave now.
Quoting weatherwatcher12:

The forecast accuracy this far out is like 1%.

No kidding! Come on now. the path has changed within 3 days drastically before, much less 3000 miles out. This can still go anywhere........ or nowhere.
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Morning all........TD2 not giving up and the Beast of the East is giving birth with 90L....here we go folks. Those that have been wishing might be soon hating what they wished for.
Member Since: September 2, 2007 Posts: 178 Comments: 20443
Hey StormW,
Top O' the morning to ya. Any thoughts on the wave entering the Bahamas? Were you able to include it in the synopsis?
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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.