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 HurricaneKyle:


Unfortunately, an anti-cyclone is moving along with 90L, protecting it against shear.
yup, so that means 90L has a big body guard that will protect him like this one:
#2 center totally exposed as shown on rgb
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Quoting P451:
Center of 90L

bigger they are the longer it takes to spin up and its spinning up
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Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
weakening flag and rapid dissipation flag all OFF
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Link

Sat presentation of wave/CB cluster N of Haiti is improving rapidly...Surface pressures remain high in the area, but shear is decreasing.
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Quoting P451:
Center of 90L

seems like convection is starting to wrap around.
90L would have to stay weak the whole way through to get into the Caribbean. At this time I don't see it getting there. There will be a decent trough advecting into the eastern CONUS with very little variation in position among the ensemble members.
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Quoting Acemmett90:

we need shear pray for shear


Unfortunately, an anti-cyclone is moving along with 90L, protecting it against shear.
Member Since: August 10, 2009 Posts: 3 Comments: 672
274. slavp
Quoting NOLaHSE:
It's amazing how many people who appear to be otherwise sensible adults bicker and dwell on "ifs". I'm assuming its out of the slow start to the season, although not a viable excuse.

Relax. You'll all get what you want in the coming weeks.

Just be careful. When it comes to the Carolinas, Florida, or any number of places on the Gulf Coast...it may not seem near as exciting!
Well said
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Quoting Cotillion:


If TD2 was a car, the cambelt may not have gone, but it only has a 4 cylinder right now and the head gasket's blown.


More like an '02 Lincoln LS with the ever-failing electrical coils.....
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Quoting weatherwatcher12:
Meanwhile this day in 2007 Tropical Depression 4 formed which would later become Major Hurricane Dean.


Meanwhile on this day in 2004, the tropical depression that would become known as Hurricane Danielle formed, and did nothing throughout its life.
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Quoting Vortex95:


Have the models kept their "monster" storm prediction?


Yessir they have. :(
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting HurricaneKyle:

Which also forcasted to be a Caribbean trucker, and was a 90L to. Very interesting coincidence.

Yeah, Dean was very strong here. It was forecaast to miss me then the track suddenly changed to right on me. That goes to show that the Hurricanes listen to no one.
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266. 7544
looks like td 2 get another shot to prve its self

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
Member Since: Posts: Comments:
Quoting Acemmett90:

thank god it will take longer to get organized


The longer it takes to organize, the more likely it will go west.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting Acemmett90:

allright we should amke a new rule jsut report and ignore troll like comments and the trolls themselfs
im sending u an email, read it.
Quoting Drakoen:
SHIPS takes 90L to hurricane strength


...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...


50KTS 65KTS 66KTS 71KTS

DSHP 50KTS 65KTS 66KTS 71KTS
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Quoting weatherwatcher12:
Meanwhile this day in 2007 Tropical Depression 4 formed which would later become Major Hurricane Dean.

Which also forcasted to be a Caribbean trucker, and was a 90L to. Very interesting coincidence.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting jasoniscoolman10:
its a map of Storm Relative 16km Microwave-Based Total Precipitable Water Imagery..

thanks
Massive

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As long as TD2 continues to fire convection it can still be classified as a tropical depression
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Meanwhile this day in 2007 Tropical Depression 4 formed which would later become Major Hurricane Dean.
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Quoting SomeRandomTexan:



Good Update Storm...



How do you view the update regarding possible GOM ramifications?
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Quoting Acemmett90:

we are sry but the truth is with all the 92 degree water anything can get ugly quick we should have just stated it like that
It's all cool. My point I was trying to get across to everyone is you have these people come on here (trolls) with the intent to lure people into replying to their comments that people actually bite. The end of Florida? Please people, anyone ought to know he is trying to get a rise out of you and you fell for it and unfortunately I did to by responding to you all. I got to go now. Still trying to get my father-in-laws house rebuilt after Ike.
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It's amazing how many people who appear to be otherwise sensible adults bicker and dwell on "ifs". I'm assuming its out of the slow start to the season, although not a viable excuse.

Relax. You'll all get what you want in the coming weeks.

Just be careful. When it comes to the Carolinas, Florida, or any number of places on the Gulf Coast...it may not seem near as exciting!
Member Since: Posts: Comments:

Charlie,in 04 showed many that a Storm dosent listen to the Forecasters.
They have no Ears.

Everyone thought He was going to Tampa,But Right turn Charley did a Lil turn and went in at Punta Gorda and caught MANY by Surprise.
As I always state,never turn your back to a Storm when its south of one,as the threat is always there till its past.
Be prepared as we lean into the meat of the season.
Ignore rumor,and follow the NHC track and Discussions for the most updated info as well.


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Quoting ssmate:

It was really underground when he joined.

lmao
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Link

we may see a similar story (different injuries of course) if we have people imitate what they see posted. DO NOT try riding out a storm for the sake of youtube or peoples entertainment. your not smart enough, it will not end well
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Quoting LBAR:
Looks like TD2 is firing up the cylinders again.


If TD2 was a car, the cambelt may not have gone, but it only has a 4 cylinder right now and the head gasket's blown.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
242. JRRP
trying to return
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Quoting FloridaTigers:
Why is every CV storm headed in a W or WNW direction the next omg "Andrew"?


-and Andrew was very small in size in comparison. This is 3000 miles away so you can name any hurricane ya want at this point..
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Quoting WeatherStudent:


An eye condition, isn't it?


Uh... no... as far as I know it is A Satellite dedicated to a particular system.
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Td 2 is finally cranking a burst of thunderstorms lets wait and see
Member Since: July 14, 2009 Posts: 0 Comments: 3022
Wunderground itself is a heckuva lot older than 2005, but Dr M's blog only dates back to then.
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Quoting Canealum03:
90L actually reminds me very little of Andrew. Remember Andrew was a very small storm. If anything, TD 2 reminds me much more of Andrew: small storm that was struggling to survive.


90L reminds me of either Floyd or Dean.
Member Since: August 10, 2009 Posts: 3 Comments: 672

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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.