Disturbance 90L close to tropical depression strength; TD 2 may rise again

By: Dr. Jeff Masters , 2:02 PM GMT on August 14, 2009

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A strong tropical wave (90L), with a large circulation and a moderate amount of heavy thunderstorm activity, is a few hundred miles southwest of the Cape Verdes Islands, off the coast of Africa. This morning's QuikSCAT pass shows that 90L has a large circulation, but this circulation is not yet well-formed, as it is elongated along an east-west axis. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are gradually becoming better organized, with some spiral banding evident on the south side of the storm. Satellite intensity estimates from NOAA already put 90L at tropical depression strength with 30 mph winds, but the storm does not yet have a well enough formed circulation to be classified as a depression. 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 was. However, there is some dry air from the SAL being sucked into the circulation of 90L, and this is retarding its development.

Wind shear is moderate, about 10 - 15 knots, but is forecast to fall to the low range, 5 - 10 knots, later today. Shear is then forecast to remain low for the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow 90L to develop into a tropical depression by Saturday, and potentially reach hurricane strength by Wednesday. Most of our reliable models strengthen 90L into a hurricane by Wednesday, when the storm is expected to be near the northern Lesser Antilles Islands. One important outlier is the ECMWF model, which has 90L passing to the north of the islands, and eventually recurving out to sea east of Bermuda. The ECMWF was by far the most reliable model for forecasting hurricane tracks last year. However, all of our models are pretty unreliable going out 5 days in advance for systems that have yet to reach tropical depression strength. Once 90L becomes a tropical depression and develops a well-formed circulation, the models will have a better handle on forecasting where it will go.


Figure 1. The remnants of Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

Tropical Depression Two may come back
Tropical Depression Two died yesterday, but may rise again. Satellite loops of the remnants of the storm show that heavy thunderstorms are again attempting a comeback near the axis of what is now a tropical wave. However, dry air continues to interfere with the development of the thunderstorm activity, and moderately high wind shear of 15 - 20 knots is also inhibiting the process. Wind shear over the remnants of TD 2 is expected to remain in the moderate range, 10 - 20 knots, over the next four days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C two days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to the north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that any re-development of the storm will be slow to occur. NHC has given the system a medium (30 - 50% chance) of becoming a tropical depression again by Sunday morning. Only one reliable model, the NOGAPS, is predicting regeneration of TD 2. The NOAA Hurricane Hunters are flying research missions into the remnants of TD 2 today and Saturday.

I'll have an update Saturday morning, or earlier, if significant developments occur.

Jeff Masters

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They're saying 90L is slightly less organized, but that doesn't surprise me seeing how large it is and its getting close to DMIN. I'll say TD on Saturday for 90L and TD2 might regenerate on Sunday.
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12Z GFDL in now futher south...models have no idea beyond 55W...
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Somthing is wrong with the HWRF... at HR 06 it has the pressure at 993mb and 900mb winds at 73kts..

Wow..

LOL
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Quoting TexasHurricane:
Link

Looks to be pretty big to, wonder how strong...


These images scare me.. I'm hoping that this exact thing doesnt happen.. It will catch people in Louisiana off guard.. We are still recovering from Gustav.. It's gonna be rough if this pans out
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TWO out, no change except a new AOI in the GOMEX.
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Quoting weathersp:
I say TD 2 is red at 2PM and if convection persists through the night then at 5 AM they will put TD2 back on the map.
Would it be TD2 or TD3? Seems like it should be 2, but?
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12Z HWRF has old TD2 as a weak hurricane in the eastern Bahamas at the end of its run...

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TD2 not a blip anymore, it's a blip supreme.
NHC has All their crayons out today!
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000
ABNT20 KNHC 141737
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT FRI AUG 14 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWER ACTIVITY HAS BECOME A LITTLE BETTER ORGANIZED IN ASSOCIATION
WITH THE REMNANT LOW OF FORMER TROPICAL DEPRESSION TWO...LOCATED
ABOUT 1225 MILES EAST OF THE LESSER ANTILLES. WHILE UPPER-LEVEL
CONDITIONS ARE ONLY MARGINALLY FAVORABLE FOR DEVELOPMENT...
REGENERATION OF THIS SYSTEM INTO A TROPICAL CYCLONE IS POSSIBLE AS
IT MOVES WESTWARD AT ABOUT 15 MPH OVER THE NEXT COUPLE OF DAYS.
THERE IS A MEDIUM CHANCE...30 TO 50 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED A BROAD AREA OF LOW
PRESSURE CENTERED ABOUT 250 MILES WEST-SOUTHWEST OF THE SOUTHERN
CAPE VERDE ISLANDS HAS BECOME A LITTLE LESS ORGANIZED OVER THE PAST
SEVERAL HOURS. HOWEVER...CONDITIONS STILL APPEAR FAVORABLE FOR
FURTHER DEVELOPMENT OF THIS SYSTEM...AND A TROPICAL DEPRESSION
COULD FORM DURING THE NEXT DAY OR TWO AS IT MOVES WESTWARD AT NEAR
15 MPH. THERE IS A HIGH CHANCE...GREATER THAN 50 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

A TROPICAL WAVE INTERACTING WITH AN UPPER-LEVEL LOW IS PRODUCING AN
AREA OF CLOUDINESS AND SHOWERS FROM JAMAICA AND EASTERN CUBA
NORTHWARD INTO THE BAHAMAS. THIS ACTIVITY IS EXPECTED TO SPREAD
WEST OR WEST-NORTHWESTWARD DURING THE NEXT COUPLE OF DAYS. THERE
ARE NO SIGNS OF ORGANIZATION AND UPPER-LEVEL WINDS ARE NOT
FAVORABLE FOR SIGNIFICANT DEVELOPMENT OF THIS SYSTEM. THERE IS A
LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

SHOWERS AND THUNDERSTORMS OVER THE NORTHEASTERN GULF OF MEXICO ARE
ASSOCIATED WITH A WEAK TROUGH OF LOW PRESSURE. SURFACE PRESSURES
ARE HIGH IN THIS AREA AND THERE ARE NO SIGNS OF ORGANIZATION.
THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BEVEN
Thanks FLWeatherFreak91! I just spent 20 minutes outside with a coworker watching the clouds. Just amazing! Wish I had my camera today...
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Alright last time I'll mention it. I see the little swirl in the Bahamas is on the Nogap model forms it into what looks like a tropical storm, maybe T D takes it into the fl panhandle in a few days. No comments am I seeing that right.
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College is much more strict on Hurricanes I guess since it is its own entity. Example would be usually if it is a TS, they will have classes the day before.

yeah my last semester we got off twice...For Ike and Gustav and all the professors tried to cram so much material in too short of a time...ugh
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I say TD 2 is red at 2PM and if convection persists through the night then at 5 AM they will put TD2 back on the map.
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HWRF 12Z hypercane forecast deluxe again! 90L to Category 5 once more...



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717. Skyepony (Mod)
I think you can wager on hurricanes through Univ in Miami.
Member Since: August 10, 2005 Posts: 161 Comments: 37341
Quoting ph34683:
What is the blob hanging out off the gulf coast of FL? I'm seeing some really strange clouds out my window!
It's the tail end of a trough. If it was further out in the Gulf and had more time to develop, I think it definitely would. But it is going to move over the peninsula before it really has enough time to organize.
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Quoting ph34683:
What is the blob hanging out off the gulf coast of FL? I'm seeing some really strange clouds out my window!


stalled front
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Is it me or does it look like 90L is gonna take a turn towards Florida.

Link
Member Since: August 9, 2009 Posts: 10 Comments: 4898
Heres comes the shift?

12z GFDL into the caribbean.
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What more would TD02 need to do to be reinstated from it's remnant low suspension?
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...SPECIAL FEATURES...
THE REMNANT LOW OF TROPICAL DEPRESSION TWO IS CENTERED NEAR
14.6N 41.7W E OF THE LESSER ANTILLES MOVING W AT 10 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS W OF THE CENTER FROM
14N-16N BETWEEN 42W-44W.


Not sure if this was up at 805, but ex TD2 is now a special feature.
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90L still has convection issues.
Member Since: October 28, 2006 Posts: 57 Comments: 29886
Quoting FLHurricaneChaser:


Yep. It really is nice when hurricanes come through. Wilma gave me a 2 week vacation in October/November 2005. It was nice :)
Yep.I just started my college experience as a meteorology major at FIT Melbourne, Fl on Monday and may have a break the second week of school ;)
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707. Skyepony (Mod)
Still watching surface obs on the wave over Cuba. The mid level vort is just NE of the center of the island. There's a nice triangle of obs from land that have formed a near perfect triangle showing a surface circulation displaced on land east of the center of Cuba. It's been there a while & I've watched the west (& north & south winds respectively) wind move to the west across 4 diffent SHIPS/stations. FL can thank Cuba & shear..
Member Since: August 10, 2005 Posts: 161 Comments: 37341
Quoting presslord:
last year Dr. Masters posted a site on which one can bet on weather futures....I'd love to see some of these people who're so certain about where things are gonna be in 7-10 days put their money where their keyboard is...


Well, a lotta folks would be out of money if they took that seriously. Especially JFV.
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Cue the Jaw's Movie Theme...

TD-2 is BAck BAby..

Baby Back TD's..sounds Like Applebee's Appetizer



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I wonder if they will put ex-TD2 to red at 2:00pm. The SHIPS text indicated favorable upper level conditions.
Member Since: October 28, 2006 Posts: 57 Comments: 29886
Quoting WatchingThisOne:


Don't tell us, tell him !!! lol


LOL,good point
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Quoting presslord:
last year Dr. Masters posted a site on which one can bet on weather futures....I'd love to see some of these people who're so certain about where things are gonna be in 7-10 days put their money where their keyboard is...


The only question there is.... Who owns the house edge???
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Quoting CybrTeddy:
Afternoon Ike, 456, Drak, Kyle, 23 and everyone else!

90L looks pretty impressive, and does a lot remind me of Pre-Dean in 2007. The models are in close agreement with the exception of the ECMWF which underestimates the forward speed of 90L, that this will either hit the Northern Lesser Antilles or go slightly north of that. A Similar Hurricane to this would be Donna. The NOGAPS shows a one two punch to Florida, but does In my opinion to much with ex TD2.


ex TD-2 still has a strong LLC, so we'll still have to watch it. Right now its sweeping up all that dust and dry air in front of 90L.
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What is the blob hanging out off the gulf coast of FL? I'm seeing some really strange clouds out my window!
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Very close to be classified as a TD.
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Quoting NEwxguy:
My brother is living in St.Croix,he better watch this thing,some models take it right over him.


Don't tell us, tell him !!! lol
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Quoting KEEPEROFTHEGATE:
ws i gonna say this once and only once

models are meant to be used as guidance purposes only and do not depict final outcome to any one event things can and will change

so if a model don't know where an when what makes you think anyone else knows

i will tell ya where its going its going forward 1 degree from its present location and it will continue moving 1 degree from its previous point till it hits something that is in front of it thats about as much as we really know at the moment anything else is just a rough idea

the best advice for anyone have a plan listen to local AUTH. evac if ordered to do so the life you could be saving may be your own


ROFLMAO... KOG your wasting your breath... want to borrow my head beating icon, it seems to help me.


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Quoting RobbWilder:


Yeah there are thousands of school kids with there eyes closed hoping it comes before back to school happens down in South Florida
School for the kids starts August 24th right in the middle of 02L and 90L.
694. IKE
Quoting NEwxguy:


I'm glad you said that,it's getting annoying the same question over and over.


Problem is....he'll keep asking, hoping someone responds.

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All this fuss over something that is still a blob. Must be all that pent up frustration from no action yet...

Way to early to say what will happen but homecasters and wishcasters just keep going, my ignore list will grow and grow and grow.

Lets use our heads. Still 0.0.0 and we know that will change, all we can say is somebody from mexico to the northeast coast will be effected at some point, by something. (probably)

Quit rushing these storms into the East coast or GOM, you will usually be wrong. They will do what they do. Last time I checked storms don't check the models.
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TD2 and 90L are almost 700miles apart they are fine co-existing if need be
Member Since: October 28, 2006 Posts: 57 Comments: 29886
Quoting RobbWilder:


Yeah there are thousands of school kids with there eyes closed hoping it comes before back to school happens down in South Florida


Yep. It really is nice when hurricanes come through. Wilma gave me a 2 week vacation in October/November 2005. It was nice :)
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Quoting Patrap:



Geez Ike,..you gotta tilt dat Machine Like a Bad O
pinball ,and keep dat Bugger away from the GOM
yeah, you'd think he would want to quit seeing bad news.
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Press, cut me some slack, OK?

Why?
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Quoting WeatherStudent:
Press, cut me some slack, OK? Excellent cane comparisons there, Adrian. By the way, does this one concern you at all, for us that is? Afternoon 456 and everyone else. :)


All he means is the "is it gonna hit s florida?" "will it hit florida" is really annoying when its not even a TD yet. Sure the models are very interesting and somewhat consistent but its still a while away.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting KEEPEROFTHEGATE:
ws i gonna say this once and only once

models are meant to be used as guidance purposes only and do not depict final outcome to any one event things can and will change

so if a model don't know where an when what makes you think anyone else knows

i will tell ya where its going its going forward 1 degree from its present location and it will continue moving 1 degree from its previous point till it hits something that is in front of it thats about as much as we really know at the moment anything else is just a rough idea

the best advice for anyone have a plan listen to local AUTH. evac if ordered to do so the life you could be saving may be your own


I'm glad you said that,it's getting annoying the same question over and over.
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Afternoon Ike, 456, Drak, Kyle, 23 and everyone else!

90L looks pretty impressive, and does a lot remind me of Pre-Dean in 2007. The models are in close agreement with the exception of the ECMWF which underestimates the forward speed of 90L, that this will either hit the Northern Lesser Antilles or go slightly north of that. A Similar Hurricane to this would be Donna. The NOGAPS shows a one two punch to Florida, but does In my opinion to much with ex TD2.
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Quoting Weather456:


I've been seeing alot of those questions and comments and it points to someone who wants something to hit Florida. Persistent questions about landfall when the asnwer is always "we dont know". Honestly its tiresome, and sad.


Yeah there are thousands of school kids with there eyes closed hoping it comes before back to school happens down in South Florida
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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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