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 PanhandleChuck:


Tell that to my friends who went through IVAN


Ivan was indeed very destructive, but its southwestern eyewall eroded prior to landfall, resulting in weakening from a Category 4 to a Category 3.
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2886. RyanFSU
HWRF 00Z run has the 90L wave to hurricane strength in 60-66 hours, with major status shortly thereafter.



Other animations.

Note: HWRF not quite done until 1:35 AM, but is through 108 hours as of this posting.
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Quoting centex:
I asked BB tonight when is last no named storm August, he did not know. Anyone know?


1997.
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2884. centex
Yea zoom in and set to max you see someting. I don't see anythig. The bigger question is whether we can have anything in august.
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2883. IKE
Quoting PanhandleChuck:


What's up Ike? Funny thing everytime I see your avatar, No Quarter starts playing in my head. LOL


Great song.

I just woke up....had my computer on...looked at the latest GFS and thought about the adage...it only takes one. This would be the "A" storm.
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Quoting chsstormgirl:
Don't mention Hugo... I think there is some old theories about the SC coast and hurricanes on years that end in 9s.... Grace,59, Hugo,89, floyd,99, and there were storms in 69 and 79,although not as big...
The 9's have been fierce for the Carolinas, but so were '54 (Hazel), '60 (Donna), '96 (Bertha/Fran), '04 (Charley/Gaston) and others. The 9 thing is a tad strange. I remember Hugo as if it were YESTERDAY. I drove through SC on 1-95 about three weeks post-Hugo, and the damage was incredible. Trees fell like toothpicks, and there was NOT ONE road sign. All of those annoying, "Pedro says such and such miles to South of The Border" were long gone. On a personal note, The Francis Marion State Forest was heavily damaged in Hugo. That forest is named after the famed "Swamp Fox", who is a very distant ancestor of mine, a great, great, great, great, great Uncle or something. In fact, my generation is the only one in many not to give "Marion" as the middle name to all the children in homage. My father hated being Henry Marion, and refused to allow us to have the name. I probably wouldn't have cared. Peter Marion sounds kinda cool, no? I was just in SC a few weeks back on I-95, and made my obligatory stop at the Swamp Fox Inn and souvenir shop!Link
If you can't see my photo, click on the link. It's safe. It's from my website, and I have no idea how to spread a virus, and wouldn't want to!
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Quoting flsky:

It makes me feel bad to read this. Please don't despair. Things will be ok, even if you are hit this year. There are innumerable people ready to help if needed - count on it.


Thanks a lot for such kind words FLSky. It's just that it's a tough time here, but so is in most parts of the World. I'm sure we'll be fine; we are a tough little island that has been blessed many times so maybe we'll be spared again. I'm lucky to live in a relatively safe zone (not flood prone area, solid structure) but I worry about others who are not as lucky. It may take us some time to recover if a hurricane hit us (and right now 90L looks scary), but we've done it in the past and we will again. ;-)
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Quoting centex:
I'm scared.


Yes that is an old image.
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2879. centex
I asked BB tonight when is last no named storm August, he did not know. Anyone know?
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>Quoting flsky:

It makes me feel bad to read this. Please don't despair. Things will be ok, even if you are hit this year. There are innumerable people ready to help if needed - count on it.


Have to agree with you guys but coping the storm and hope for the best , wouldn't ever leave my beloved island.
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2877. JLPR
oh before I go



^^^^
90L sure is liking D-max
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Quoting centex:
I'm scared.


Uh

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The GFS has been very insistant on a major system going between SE Louisiana and the east coast of Florida, for about a week now. On a globel scale, that's a small cone of error given the length of traval. If it comes to pass, that's a very respectful forecast.
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2874. JLPR
well im out
lets what I wake up to tomorrow

goodnight everyone =D
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Quoting IKE:
That GFS run has 90L reaching the islands in 138 hours...less than 6 days.

I'm surprised it still shows a GOM hit.

What happened to the trough? lol.


What's up Ike? Funny thing everytime I see your avatar, No Quarter starts playing in my head. LOL
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2872. centex
I'm scared.
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2871. IKE
Also....seems to speed up 90L....move faster.
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2870. JLPR
thanks extreme and Hades

I tend to notice things late lol
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Quoting PanhandleChuck:
I was at Pensacola Beach yesterday and the water was extremely warm. I know it's shallow there, but by the looks of all the SST maps that have been posted and listening to NOAA's marine report, 90L could be one long fuse for the powder keg
Ditto just got back from my vacation at St. George Island,i would describe the water temp as lukewarm bath water.........
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2868. IKE
That GFS run has 90L reaching the islands in 138 hours...less than 6 days.

I'm surprised it still shows a GOM hit.

What happened to the trough? lol.
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2867. HadesGodWyvern (Mod)
JLPR

It was issued at 1900z (3:00 PM EDT)
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2866. 7544
dont think anyone will wait to seea 3 day cone to get out if this monster is threaning their area
Member Since: May 6, 2007 Posts: 0 Comments: 6855
2865. Wariac
Hugo o Georges it doesn't matter. Both hit us pretty hard here in Fajardo, PR. This new one really looks like is gunning for us. Hope it doesn't, we don't need it right now.
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Quoting centex:
90L looks like crap. Why so much fuse?


Must be looking at the wrong system.
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Quoting JLPR:


Is this recent?
just saw it on the navy page


Its been out for several hours actually.
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2862. centex
90L looks like crap. Why so much fuse?
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Quoting chsstormgirl:
Don't mention Hugo... I think there is some old theories about the SC coast and hurricanes on years that end in 9s.... Grace,59, Hugo,89, floyd,99, and there were storms in 69 and 79,although not as big...


I don't think I have heard that one before, and if I have, must have chosen to conveniently forget that theory. :-)
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2860. JLPR


Is this recent?
just saw it on the navy page
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2859. flsky
Quoting alpha992000:


Well, I keep saying a hurricane it's the only thing left to happen here this year. In between the economy, the AH1N1 and the recent tremors being felt near the Island, I'm pretty sure PR is gonna end up "disappearing" one way or another. Pick your favorite destination, sadly we might have to get outta here soon.

It makes me feel bad to read this. Please don't despair. Things will be ok, even if you are hit this year. There are innumerable people ready to help if needed - count on it.
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Any GFS landfall forecasts should be taken with a grain of salt. The bottom line right now is that LA to NC seems to be the highest risk areas....which is a big chunk of area. Don't focus on the exact track predicted, focus on the consistency with which it's forecasting a US threat.
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2857. RyanFSU
Following up on Drakoen, here is mouse-over selection of images that allows you to compare current SST with the same date from 1982-2008 and a comparison between the two years.

Here's the current 2009 SST:


The Gulf is warm but other areas of the tropical Atlantic are cooler than during 2005, amazingly.

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Quoting chsstormgirl:
Don't mention Hugo... I think there is some old theories about the SC coast and hurricanes on years that end in 9s.... Grace,59, Hugo,89, floyd,99, and there were storms in 69 and 79,although not as big...


I hear ya. Hugo was pretty bad in here (Puerto Rico) as well, though I think not as bad as Georges in 1998. Best wishes for you guys. May the 9s "curse" be broken this time.
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Quoting FLHurricaneChaser:


Doesn't matter how hot the water is there. It is SHALLOW, and any approaching hurricane will weaken big time.


Tell that to my friends who went through IVAN
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Looking at the latest RAMSDIS imagery it appears 90L has managed to fire some pretty decent convection over the center finally. Perhaps we might see a TD soon... When will the next TAFB readings come out?
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2853. JLPR
Quoting alpha992000:


Well, I keep saying a hurricane it's the only thing left to happen here this year. In between the economy, the AH1N1 and the recent tremors being felt near the Island, I'm pretty sure PR is gonna end up "disappearing" one way or another. Pick your favorite destination, sadly we might have to get outta here soon.


yep its a big mess =\
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Quoting PanhandleChuck:
I was at Pensacola Beach yesterday and the water was extremely warm. I know it's shallow there, but by the looks of all the SST maps that have been posted and listening to NOAA's marine report, 90L could be one long fuse for the powder keg


Doesn't matter how hot the water is there. It is SHALLOW, and any approaching hurricane will weaken big time.
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Quoting JLPR:


yeah I lost power yesterday but it was only for one or two minutes

another Georges = No Puerto Rico

with the economy like it is that would wipe us off the Caribbean =S


Well, I keep saying a hurricane it's the only thing left to happen here this year. In between the economy, the AH1N1 and the recent tremors being felt near the Island, I'm pretty sure PR is gonna end up "disappearing" one way or another. Pick your favorite destination, sadly we might have to get outta here soon.
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I was at Pensacola Beach yesterday and the water was extremely warm. I know it's shallow there, but by the looks of all the SST maps that have been posted and listening to NOAA's marine report, 90L could be one long fuse for the powder keg
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yes most hurricanes from the south are the one that affect the island the strongest ,crossing the island and exciting north west.You might find this interestingLink
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Quoting sctonya:


That was mentioned yesterday by chucktown...it seems 9's are not good for SC!!


I'm thinking it's just an old wives tale! At least, I'm telling myself that...
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the Admins for dran sure will start baning if that storm got in too the gulf if any one where too get off key


so has soon has 90L starts cooking the Admins start baning


all so this blog will be come flooded in a few days when 90L starts cooking



so if you dont want to get ban stay on key
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The date the last gfs run has 90L approaching the US is 00Z august 23. Thats only 9 days from now. That means this thing must be really moving. I know it has to move quickly to miss the trof and that seems to be quick enough. This next week will be very interesting.
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2844. JLPR
Quoting hydrus:
JLPR-How are you,have not seen you post in a long time.


I have been here all week =P
I just don't post as much as I used to... University xD
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2843. Patrap
18Z GFS,Bad un Drak,Like Last night
Member Since: July 3, 2005 Posts: 426 Comments: 128632
2842. hydrus
Quoting JLPR:
The GFS track is very similar to Georges track in 98

JLPR-How are you,have not seen you post in a long time.
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Quoting TampaSpin:
This is not good......LOOK at the GOM it is like a time bomb ready to explode...32deg celisus..WOW


Yeah, I REALLY hope nothing gets or forms there (virtually impossible though). It certainly looks spooky.
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Who else thinks TWC has totally sold out now, with Al Roker and NBC? Roker is known in my area as an NYC met, but since he's on the Today Show, I guess he's a nation-wide personality as well. Still, I don't consider him a great meteorologist, rather a likable man with a good voice and great teleprompter skills. And as far as TWC itself, I worked with them in 2007 for a hurricane special, and it and I appeared on air that May (it's on youtube, my name is jackbuster). All I have to say is that the people they sent me knew absolutely zero about tropical weather, and that's when I knew that TWC had gone down like the Titanic. I mean they didn't even KNOW who John Hope was when I told them he was my idol for twenty years. I'll leave you with this, "Head On, Apply Directly to the Forehead".
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2839. sctonya
Quoting chsstormgirl:
Don't mention Hugo... I think there is some old theories about the SC coast and hurricanes on years that end in 9s.... Grace,59, Hugo,89, floyd,99, and there were storms in 69 and 79,although not as big...


That was mentioned yesterday by chucktown...it seems 9's are not good for SC!!
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2838. JLPR
Quoting alpha992000:


Heck, yesterday many were left without power and it was just some rain and thunderstorms. Another Cat 3 like Georges... nah, I don't even want to think about that. O_o


yeah I lost power yesterday but it was only for one or two minutes

another Georges = No Puerto Rico

with the economy like it is that would wipe us off the Caribbean =S
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Don't mention Hugo... I think there is some old theories about the SC coast and hurricanes on years that end in 9s.... Grace,59, Hugo,89, floyd,99, and there were storms in 69 and 79,although not as big...
Member Since: Posts: Comments:

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.