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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Expect possible missing/delayed satellite images. GOES east station keeping maneuver.

On Thursday, August 13, the following exclusive schedule will be
employed to support maneuver operations: (*PLEASE NOTE the scheduled
GOES-11 (GOES-West) Full Disk scan period to support the primary
GOES-12
(GOES-East) outage during the maneuver.*)

GOES-12 (GOES-East) Maneuver Schedule starts at 1905 UTC on Thursday,
August 13, 2009.
(Southern Hemisphere Scan at 1909 UTC is canceled)

>From 13/1915 UTC through 14/0059 UTC -- GOES-12 (GOES-East) Routine
Imaging and Soundings.

*From 14/0100 UTC through 14/0214 UTC -- No GOES-12 (GOES-East) Imaging
or Soundings*

**From 14/0100 UTC through 14/0229 UTC -- GOES-11 (GOES-West) Full Disk
Imaging**

>From 14/0215 UTC through 14/0914 UTC -- GOES-12 (GOES-East) Post
Maneuver Recovery Including (updated for KOZ interference):
* Full Disk Images (19 minute scan) at XX15 and XX45
* CONUS Soundings at XX46
* 0415, 0445, 0515 & 0545 Short Full Disk Images will be canceled.
* The following images have been scheduled in place of the Short Full
Disk Images:
- 0445 - Northern Hemisphere Extended Image
- 0456 - CONUS image
- 0515 - CONUS image
- 0522 - CONUS image
- 0545 - CONUS image
- 0556 - CONUS image

0915 UTC August 14 -- GOES-12 (GOES-East) Routine Scan Operations
Resume

Expect GOES-12 (GOES-East) imager and sounder gridding offsets for
up to
6 hours following the maneuver.



Member Since: September 23, 2005 Posts: 14 Comments: 10875
Quoting druseljic:


http://www.ssd.noaa.gov/goes/east/gmex/loop-vis.html

or

http://www.ssd.noaa.gov/goes/east/watl/loop-vis.html


Thank you!
Member Since: Posts: Comments:
1135. Prgal
Quoting TampaSpin:


Hum.....your looking at about 7 days out from there.....is my best guess...


Hmm, maybe its my english Tampa, no worries. Let me try to rephrase it. The models are more accurate for 1 day...2 days? 90L is about 7 days away from PR...but how accurate is that (considering that I am aware that it might change due to other conditions in the atmosphere). How far in time can the models be trusted?
Member Since: Posts: Comments:
geeez!!! i can't stand TWC, so much for the tropical at 50 before the hour...it's either the damn "oh it could happen now" or "storm stories"......I want my TWC2....


HEAD ON....."Apply directly to the forhead"
Member Since: Posts: Comments:
1133. slavp
Quoting CaneWarning:


Is that the one that was missing for the past 15-20 years?
Yes, I saw the story on TV the other night. God bless his family for having to endure that for all these years
Member Since: Posts: Comments:
1131. SQUAWK
Quoting WeatherStudent:


hey ex, true, or it could certainly strike teh conus as well.


Well, that proves it. You just can't fix stupid.
Member Since: Posts: Comments:
Quoting Prgal:


Yes I know and I do follow the advices. What I want to know is about the accuracy of the models.


The accuracy of an NHC forecast at 5 days out is +/- 300 miles. This is as good a forecast as you can get, because it includes all models plus expert human interpretation.

So if you're talking about only 1 model, no human interpretation, and more than 5 days, you can see that the "cone of uncertainty" is absolutely huge.
Member Since: Posts: Comments:
Quoting WeatherStudent:


hey ex, true, or it could certainly strike teh conus as well.


WS its more like to follow you everywhere and anywhere you go.....at least in your mind that is......JUST KIDDING YOU!
Member Since: September 2, 2007 Posts: 178 Comments: 20439
1127. WxLogic
Quoting OSUWXGUY:


In general, the quicker 90L organizes with only a moderately strong ridge to its north, the more latitude it would gain. A slower organizing system, based on lower level steering currents would gain less latitude and would be more a threat to the Lesser Antilles in 5 days...


Definitely... since ECMWF is being aggressive on this run... then the is feeling more atmosphere and recurving sooner.
Member Since: Posts: Comments:
Quoting Prgal:


I am in Puerto Rico Tampa.
I may not always be the sharpest knife, but I did deduce:
1)from PR
2)not male

(j/k :p Tampa)
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jasoniscoolman10,

I must tell you that am SHOCKED by such immature, and poor grammatical posting. If one were to guess anything about you, based on the pic you provided.. it would say "Jason clearly has his life together. He is well educated, and doesn't live in his mother's trailer" Now perhaps you just had a bad day at your law firm, or your trophy wife overspent on your black AMEX card....

.. just let's get back to being the REAL, TRUE, Jason... that so transparently is you.
Member Since: Posts: Comments:
12z GFS has this system nearing the Leewards in the Wednesday-Thursday timeframe, however, it may just as well miss these islands entirely if a trof off the East coast begins to pull it northward before then (12z ECMWF). Both are good possiblities, but my honest opinion is that this will threaten a landmass (whether it be an island or a continent) somewhere down the road. Too far out to tell exactly where.
Member Since: Posts: Comments:
Quoting FloridaTigers:


Why is South Florida consistently your big target? Why not Central Florida? Or the Carolinas? or PR?

Because Florida sticks out like a sore thumb in the middle of the ocean and is basically always affected by a storm that passes by.
Member Since: Posts: Comments:
1121. fire635
Quoting WeatherStudent:


hey ex, true, or it could certainly strike teh conus as well.


REALLY!?? Just once PLEASE... I want to see you type T H E In a row. That would be the word THE
Member Since: Posts: Comments:
Quoting TexasHurricane:
Anyone got a link to the GOM/Carribean area?


http://www.ssd.noaa.gov/goes/east/gmex/loop-vis.html

or

http://www.ssd.noaa.gov/goes/east/watl/loop-vis.html
Member Since: Posts: Comments:
Quoting jaxbeachbum:
With showers and thunderstorms moving through the Jacksonville area, the remains of Capt. Scott Speicher arrived at NAS Jacksonville this afternoon. I won't bother posting the link but you can follow on any Jax news station. Burial will be tomorrow. God bless him for his service to this country as well as all who have and continue to do so!!


Is that the one that was missing for the past 15-20 years?
Member Since: Posts: Comments:
1118. Magical
Quoting WeatherStudent:
g'afternoon all! I'm back, discard teh latest ecmwf model as it ahs a december liek through picking up our storm and taking it otu to sea, plz


What? Can you speak English?
Member Since: Posts: Comments:
Quoting Prgal:


I am in Puerto Rico Tampa.


Hum.....your looking at about 7 days out from there.....is my best guess...
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Quoting WeatherStudent:



hey ex, true, or it could certainly strike teh conus as well.


Or it could recurve out to sea.
Member Since: Posts: Comments:
Quoting seminolesfan:
The NHC would issue watches/warnings for your area. PR, right? It is always safest to follow their advisories and make decisions based on that info.
Best statement I've seen all day, Heck All season..Back to lurking
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1113. Prgal
Quoting seminolesfan:
The NHC would issue watches/warnings for your area. PR, right? It is always safest to follow their advisories and make decisions based on that info.


Yes I know and I do follow the advices. What I want to know is about the accuracy of the models.
Member Since: Posts: Comments:
The NHC satellite image for 90L is only showing the western fringe, with TD2 to the NW. Same with the loop.

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Anyone got a link to the GOM/Carribean area?
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Quoting canesrule1:
Hey guys the curve all u people keep talking about was stated on the news as "highly unlikely" so i wouldn't be saying that SFLA is out of the picture.


Why is South Florida consistently your big target? Why not Central Florida? Or the Carolinas? or PR?
Member Since: Posts: Comments:
1109. Prgal
Quoting TampaSpin:


Where do you live at.....that helps


I am in Puerto Rico Tampa.
Member Since: Posts: Comments:
Quoting Prgal:
Ok guys, I have a question. I know that these models are not 100% accurate and that there will changes along a storm's way. But, I would like to know, when should I worry about a possible impact to my area (for example)? 72hrs? More? Less? TIA
The NHC would issue watches/warnings for your area. PR, right? It is always safest to follow their advisories and make decisions based on that info.
Member Since: Posts: Comments:
If you own a home in a Hurricane prone area and do not have Wind & Hail and Flooding I would be worried from June to October. if you do have the above all you need to worry bout is to have a hurricane kit and keep your eye on the reports.
Member Since: Posts: Comments:
1105. Prgal
Quoting Orcasystems:


You should always be prepared to go.

Oh, believe me I am! Have been through a couple of hurricanes already and I am ready since the begining of the season. Just a question I have always had :)
Member Since: Posts: Comments:
Quoting Orcasystems:


You should always be prepared to go.


I second that. Be prepared for anything even if the models don't initially have a storm heading in your direction, a lot of things could change.
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Blog Update
Reflector site for those at work, which includes Weather456, daily update.


TD2

90L

AOI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
1102. LBAR
Is Invest90 creating the Easterly shear for TD2? It looks the northern/western fringe of I90 is blending into the eastern fringe of TD2.
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thanks terra...
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Quoting WeatherStudent:
g'afternoon all! I'm back, discard teh latest ecmwf model as it ahs a december liek through picking up our storm and taking it otu to sea, plz


It could certainly go out to sea.
Member Since: Posts: Comments:
1099. Thaale
Hebert Box(es): IIRC the two Hebert Boxes are each bounded on the N and S by 20° N lat and 15° N lat. Box #1 is between 60° and 65° W, and box #2 is between 80° and 85° W.

The idea is that if a storm passes through one of those boxes, South Florida should take notice. Not everything that passes though Box #1 becomes a SE FL threat, but most of what passes over or under the box misses SE FL.

Box #2 is more relevant for late season, Caribbean-developing storms like Wilma.

Andrew barely missed the NE corner of box #1 and he nailed Miami nevertheless, so of course nothing is guaranteed either way.
Member Since: Posts: Comments:
Quoting Prgal:
Ok guys, I have a question. I know that these models are not 100% accurate and that there will changes along a storm's way. But, I would like to know, when should I worry about a possible impact to my area (for example)? 72hrs? More? Less? TIA


Where do you live at.....that helps
Member Since: September 2, 2007 Posts: 178 Comments: 20439
1097. slavp
Quoting WeatherStudent:
g'afternoon all! I'm back, discard teh latest ecmwf model as it ahs a december liek through picking up our storm and taking it otu to sea, plz
?????????
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Quoting jasoniscoolman10:
09L IS 3,000 MILES WAYS FOR THE USA U PEOLPE DO NOT KNOW SHIT WHERE THIS STORM IS GOING IN 7 DAYS FROM NOW..I BET YOU ITS NOT GOING TO BE A FISH STORM LETS TALK ABOUT SOMETHING ELSE..STOP TALKING ABOUT 90L BEING A FISH STORM ITS SILLY TALK TO ME. U ARE WAITING TIME Talking ABOUT FISH STORM WHEN THE STORM IS SO FAR ALLWAY FROM THE USA...
Don't be upset, Jason. We all have divergent opinions on every matter. Your thinking is just as good as everyone else's. Stand proud, and do not try to fight a losing battle of one opinion versus another...it is not worth the energy. In a week or so, let's see if it was indeed a fish storm or not. Willy Wonka says, "We should never doubt what no one is certain of."
Member Since: July 10, 2007 Posts: 0 Comments: 418
Quoting Prgal:
Ok guys, I have a question. I know that these models are not 100% accurate and that there will changes along a storm's way. But, I would like to know, when should I worry about a possible impact to my area (for example)? 72hrs? More? Less? TIA


You should always be prepared to go.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Hi all! I've been reading your blogs for along time and decided to sign up and become part of it... I'm from NOLA and just love reading all the interesting info all of you have to share. Your all so informative. Thanks!!!
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Quoting Nolehead:
got a question for teh experts on here...(and you all know who you are). everyone is saying fish...i just looked at all the maps on teh FSU site and so far there is no sign of curvature....any ideas why everyone is saying fish other than crossed fingers???


Some of the models (namely ECMWF and GFS) are showing a trof approaching the East coast by the time 90L's future self is approaching land, which could recurve it. It all depends on timing, and this far out this scenario is nothing more than a possiblity.
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For what it is worth, Joe Bastardi's video from this morning. Link
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1090. Prgal
Ok guys, I have a question. I know that these models are not 100% accurate and that there will changes along a storm's way. But, I would like to know, when should I worry about a possible impact to my area (for example)? 72hrs? More? Less? TIA
Member Since: Posts: Comments:
1089. slavp
Quoting jasoniscoolman10:
that fast..and not good news at all. are you saying we are going to have tropical d three at 5pm???????
NO, He was stating that his local news said we COULD have one
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Quoting canesrule1:
Hey guys the curve all u people keep talking about was stated on the news as "highly unlikely" so i wouldn't be saying that SFLA is out of the picture.


Too early for taking FL. out of the picture there is not even a storm yet. Have you seen the gulf it is boiling....
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1087. TeJoe
Quoting sctonya:
Keeper, do you have the link to the google map that zoomiami was working on? TIA



Here's the Link but it's old. http://orcasystems.ca/debbie.htm
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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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