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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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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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.
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Quoting fire635:


Are you just looking for a rise out of people?

Just look at his blog name?
I think his answer to this is yes.
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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.
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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
Member Since: June 13, 2009 Posts: 2 Comments: 11679
Quoting canesrule1:
yeah, and SFLA is in danger, i know its 3000 miles away but the model support with a SFLA hit is tremendous.

The forecast accuracy this far out is like 1%.
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Quoting CaneWarning:


Everyone I know from Tampa evacuated to Orlando. Big mistake.


My dad went to daytona beach and it ended up ripping the roof off his hotel over there while we (in the center of the cone in Pasco County) barely got a sprinkle.
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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

Great update as always StormW, Any chance you'll be calling into Barometer Bobs show tonight?
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Quoting PSL2007:


The confidence level is extremely low at this point. It is too far out into the future.
im giving it about 30% for a SFLA hit.
Quoting Acemmett90:

oh did your read the miami harlod today duffys got a great review and we are sponcers of the miami dolphins
yup, i heard this morning, congrats, lol.
3189. RadarRich 2:48 PM GMT on August 13, 2009
apology for repost, new to this posting,,,just got lost in the transition to new blog

Just an observation and something that may need to be monitored a little more closely. Watching quite a few satelite images and loops for the last few hours. AOI just to the east of the SE Bahamas is showing more signs of circulation and much more convection quickly.
Probably a mid level entity at present, but it bears watching since it is close to any significant populated land mass. The area aprox. 21-23 north & 68-69 west moving WNW

StormW? probably address this in your synopsis
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I agree, but that should change in the next 24 hrs.
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Quoting hurricanejunky:


We were in S. Ft. Myers then so we only got strong TS winds with Hurricane gusts. Scary day for many folks...the most stifling heat and humidity I've ever been in was after the storm and I've lived in South FL my whole life. What a miserable week that was...


Everyone I know from Tampa evacuated to Orlando. Big mistake.
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Quoting P451:


Yep.



Takes time for these to spin up. Seems more active than I expected though it's really gotten it's act together the past few hours.

its really looking good!, with highest winds on the lower band of over 30 knots, and high winds over the center but they seem to be rain contaminated.
Quoting canesrule1:
yeah, and SFLA is in danger, i know its 3000 miles away but the model support with a SFLA hit is tremendous.


The confidence level is extremely low at this point. It is too far out into the future.
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Quoting apocalyps:
There will be 3 hurricanes in the Northern Atlantic next week and 2 off them will hit hard.A disaster.


Are you just looking for a rise out of people?
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Quoting Acemmett90:

crap i begining to think the gfs is actully right
yeah, and SFLA is in danger, i know its 3000 miles away but the model support with a SFLA hit is tremendous.
02L
MARK
14.4N36.6W


AOI
MARK
20.4N/68.3W
Member Since: July 15, 2006 Posts: 170 Comments: 53489
Quoting CaneWarning:


5 Years ago today I was doing the same. Fortunately, Charley was a non-event in Tampa. Too bad it wasn't the same further south.


We were in S. Ft. Myers then so we only got strong TS winds with Hurricane gusts. Scary day for many folks...the most stifling heat and humidity I've ever been in was after the storm and I've lived in South FL my whole life. What a miserable week that was...
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Though nowhere near a Charley, this is what happened to a village about 20-30 minutes away from my hometown about 5 years ago:

Link
Member Since: August 23, 2008 Posts: 7 Comments: 5300
This was part of this mornings disco here in Charleston mentioning the wave north of Haiti

THE ECMWF ON THE OTHER
HAND...SUGGESTS THAT THE UPPER RIDGE WILL BREAK DOWN BRIEFLY MONDAY
AS NORTHERN STREAM SHORTWAVE ENERGY AND ENERGY FROM A WEAK TROPICAL
WAVE INTERACT WITH THE REMNANTS OF THE UPPER TROUGH CURRENTLY
AFFECTING THE AREA. GIVEN LARGE CONSENSUS FROM OPERATIONAL AND
ENSEMBLE GUIDANCE SUGGESTING UPPER RIDGING WILL HOLD STRONG OVER THE
SOUTHEAST CONUS...WILL CONTINUE TO FAVOR THIS IDEA THROUGHOUT THE
EXTENDED FORECAST.
Member Since: August 27, 2006 Posts: 0 Comments: 1735
Quoting JugheadFL:



Looks like the LLC is somewhat elongated, or at least not fully consolidated.
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looks closed, though elongated....
Member Since: August 22, 2006 Posts: 0 Comments: 1455


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TD2 still has a nice circulation,until it loses that circulation,need to watch it,90L is defiinitely the one to watch though
Member Since: September 6, 2007 Posts: 877 Comments: 15706
TD2.. 90L... The bahamian blob is building... and it looks like the eastern carribean AOI is starting to build some convection too. Hmm... it'll be fun to watch all this today
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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 for the update. I'll keep checking on on the GOM.
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3189. RadarRich 2:48 PM GMT on August 13, 2009
apology for repost, just got lost in the transition to new blog

Just an observation and something that may need to be monitored a little more closely. Watching quite a few satelite images and loops for the last few hours. AOI just to the east of the SE Bahamas is showing more signs of circulation and much more convection quickly.
Probably a mid level entity at present, but it bears watching since it is close to any significant populated land mass. The area aprox. 21-23 north & 68-69 west moving WNW
Member Since: Posts: Comments:
Looks like a closed circulation on the new invest

Link
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Quoting hurricanejunky:
Morning everybody!
That wave entering the Bahamas is starting to flare up again, eh? Any models developing it?

90L looks like it might turn out to be like one of the many other Cape Verde storms. Certainly one to watch.

5 years ago today I was making my final preparations for Charley. What a day that was!


5 Years ago today I was doing the same. Fortunately, Charley was a non-event in Tampa. Too bad it wasn't the same further south.
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I'm going to create a more detailed analysis of 90L on my blog here in a second.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting norfkstreetdoc:
Ok...REAL new at this but have been lurking for sometime (so please dont burn me :) ) I was looking at the area just north of Hati. It seems to be building in warm seas and about to enter an area of significantly lower shear. Any thought on this developing?

Jason




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Morning everybody!
That wave entering the Bahamas is starting to flare up again, eh? Any models developing it?

90L looks like it might turn out to be like one of the many other Cape Verde storms. Certainly one to watch.

5 years ago today I was making my final preparations for Charley. What a day that was!
Member Since: Posts: Comments:
Good morning everyone!

Here's my analysis of the situation.

TD2 is only going have a brief summary, I'm unimpressed but it still has a shot if it can take advantage of the conditions in front of it.

Now 90L concerns me. 90L is MASSIVE and will take atleast 24 hours for it to continue to become better organized because of its massive size, to bring together its convection and there on forth steady intensification to possibility Hurricane status as it gets close to the Islands. It's a long ways out, so we have a lot of time to track it.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Ok...REAL new at this but have been lurking for sometime (so please dont burn me :) ) I was looking at the area just north of Hati. It seems to be building in warm seas and about to enter an area of significantly lower shear. Any thought on this developing?

Jason
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nice update doc ships take 90l up to 71 kts in 120 hr outlook be interesting to see a few more runs
Member Since: July 15, 2006 Posts: 170 Comments: 53489
Quoting apocalyps:
TD2 is going to the carribbean.
To become biggest storm ever seen.
It will bow up from nothing to CAT5 in 40hours time.


I would watch yourself... eventually talk like that might get you banned
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Quoting apocalyps:
TD2 is going to the carribbean.
To become biggest storm ever seen.
It will bow up from nothing to CAT5 in 40hours time.


Are you serious?
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Quoting cg2916:

You can see it has a broad circulation.
broad circulation means big storm like gilbert in 88'

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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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