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

By: Dr. Jeff Masters , 2:02 PM GMT en Agosto 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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Hey Ike....lived in Defuiak during Opal....what a mess!
Member Since: Posts: Comments:
Nothing is working this year

I found out where 95L was.....


Member Since: Julio 24, 2005 Posts: 407 Comments: 19076
Quoting Weather456:
The weather channel sure is happy tonight

"maybe even a tropical storm"


PLEASE!! If I have to hear pre-Ana again.......
Member Since: Julio 31, 2006 Posts: 56 Comments: 8112
Quoting HurricaneKyle:
No renumbering on 90L, no TD3. TD2 however is back from the grave and was renumbered.
I don't understand why TWC will say we have 2 TD's
Wow! Did they really have a Tropical report?
Member Since: Posts: Comments:
Quoting Weather456:
Invest 91L is a mix breed between Td2 and 90L



LOL, not quite sure if I've ever seen that before. Someone at the Navy must be on crack...
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Quoting DM21Altestic:
School being closed for hurricane(s) in Florida - >>> teenage boys having to wait a week or longer to hook up with a girl and get laid...nothing wrong with a few closures...




Whoa, a hurricane means no school? Gnarly. I bet it brings on some like, tasty waves, too. Righteous.
Member Since: Posts: Comments:
Link

Nice little convective cell moving thru the Florida staits...
Member Since: Posts: Comments:
The weather channel sure is happy tonight

"maybe even a tropical storm"
Member Since: Julio 24, 2005 Posts: 407 Comments: 19076
Quoting canesrule1:
We have TD#2 and TD#3 as reported by the TWC.
no calls yet from the NHC we shall see within the hour
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ok so let me see if i got this right td2 which everyone said was dead is not dead and is now 91L and 90L is TD Bill? If im wrong sorry but its kind of hard to read all the posy and such.
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2671. IKE
Quoting tharpgomex:
is anyone on here from the Panama City area?


Close....Defuniak Springs,FL.

Paul Goodloe said we may have a TS at 11.
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No renumbering on 90L, no TD3. TD2 however is back from the grave and was renumbered.
Member Since: Agosto 10, 2009 Posts: 3 Comments: 672
Quoting Chiggy007:
***NOPE - nothing on the NAVY site about 91L ***


Check again ...

2009 Storms
All Active Year


Atlantic
91L.INVEST
90L.INVEST
02L.TWO

East Pacific
10E.GUILLERMO
09E.NINE

Central Pacific

West Pacific
94W.INVEST
91W.INVEST
01C.MAKA
Member Since: Posts: Comments:
2668. Patrap
Official NAVY Page
Member Since: Julio 3, 2005 Posts: 428 Comments: 129844
Quoting Weather456:
Invest 91L is a mix breed between Td2 and 90L



Navy probably just didn't know how to handle issuing a TCFA for 02L so they made 91L lol
Member Since: Agosto 2, 2007 Posts: 19 Comments: 19234
The gulf wave must be watched. Its the GULF.
Member Since: Agosto 31, 2008 Posts: 0 Comments: 833
2664. snotly
Relax everyone the Navy has an official name for the storm; Tropical Storm 02L = "NONAME"
Member Since: Posts: Comments:
. DM21Altestic :
Some discussions, and song titles, are not all that appropriate for public consumption.
Member Since: Agosto 16, 2007 Posts: 6 Comments: 12463
We have TD#2 and TD#3 as reported by the TWC.
Quoting Seflhurricane:
looks like we may have 2 TDS within the hour look out northern leeward islands, Bahamas and south florida


And it is as if the Leeward Islands didn't have enough to worry about.
Member Since: Julio 31, 2006 Posts: 56 Comments: 8112
90L and 02L continue to look better organized, and if they keep it up, we could see TD2(again) and TD3 by 11pm.




Member Since: Agosto 9, 2009 Posts: 10 Comments: 5082
Invest 91L is a mix breed between Td2 and 90L

Member Since: Julio 24, 2005 Posts: 407 Comments: 19076
FNMOC navy site is my backup for NRL.
Member Since: Junio 9, 2007 Posts: 4 Comments: 15950
Quoting pcolasky:
Hey Tampaspin, What do you think of the two areas in the Gulf coast. I don't see much happening with the area nearest the coast, but what about the one over Cuba/Hispanolia?


I was just looking at that...hum...there is an area just of the NE Cuban coast that has a very well Stacked Vorticity from 850 to 550mb. This will make it into the GOM tomorrow afternoon. There is very light Shear and conditions will be ripe. It has not developed because it has mainly been over Cuba. This bares alot of watching late tomorrow and Sunday.
Member Since: Septiembre 2, 2007 Posts: 179 Comments: 20448
2656. IKE
Quoting extreme236:


Brb, NOAA's at my door lol


LOL.

I was going to watch some comedy shows tonight. Then I recanted. Figured the blog would provide more laughs.
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is anyone on here from the Panama City area?
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***NOPE - nothing on the NAVY site about 91L ***
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Quoting extreme236:


Brb, NOAA's at my door lol
LMAO!!!
2651. aquak9
thanks, altestic. You were here before Katrina, right? You just changed your name a little. :)
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Quoting boatmanoki:
Can someone seen me the link to the Navy site

My blog (click handle) has links to Navy, NCEP models, CIRA, NHC, SST, spaghetti plots, satellite, shear forecasts, genesis models, SAL, quikscat, radar (all of them), rainfall, hurricane archives, water level data, and more. And if you call today, you get 2 for the prices of one ($19.95).

Seriously, I built a set of my personal favorites that anyone is welcome to.
Member Since: Agosto 16, 2007 Posts: 6 Comments: 12463
Quoting Chiggy007:
THERE IS NOTHING ABOUT 91L ON NAVY SITE - QUIT PUTTING FALSE INFO ON HERE PLS


lol there is, the Navy site accidentally re-named 02L as 91L, when 02L is still the same entity.
Member Since: Agosto 10, 2009 Posts: 3 Comments: 672
2009 Storms
All Active Year


Atlantic
91L.INVEST
90L.INVEST
02L.TWO

East Pacific
10E.GUILLERMO
09E.NINE

Central Pacific

West Pacific
94W.INVEST
91W.INVEST
01C.MAKA
Member Since: Posts: Comments:
Bastardi(o) , haha, always wants somehting to hit NY City - I guess one day he'll be successful LOL
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It's on the other Navy site that Pat sent Taz earlier today.


Atlantic
91L.INVEST
90L.INVEST
02L.TWO
Member Since: Posts: Comments:
looks like we may have 2 TDS within the hour look out northern leeward islands, Bahamas and south florida
Member Since: Posts: Comments:
Quoting Chiggy007:
THERE IS NOTHING ABOUT 91L ON NAVY SITE - QUIT PUTTING FALSE INFO ON HERE PLS


Except there is.

91L
Member Since: Julio 31, 2006 Posts: 56 Comments: 8112
Quoting sammywammybamy:


There Joking... Its Still 02L

Atlantic
90L.INVEST
02L.TWO



East Pacific
10E.GUILLERMO
09E.NINE



Central Pacific
01C.MAKA



West Pacific
94W.INVEST
91W.INVEST





91L is the real deal kid.

Member Since: Junio 9, 2007 Posts: 4 Comments: 15950
This has 91L, 90L, and TD2

Link
Member Since: Posts: Comments:
Quoting DM21Altestic:

Joe Bastardi jizzed in his pants staring at a couple of the northern outliers.


Yeah, I fully expect Bastardi to tell everyone in New England that this is the "Big One."
Member Since: Posts: Comments:
Quoting sammywammybamy:


There Joking... Its Still 02L

Atlantic
90L.INVEST
02L.TWO



East Pacific
10E.GUILLERMO
09E.NINE



Central Pacific
01C.MAKA



West Pacific
94W.INVEST
91W.INVEST




no we r not:Link
Quoting IKE:


LOL!


Be right back, NOAA's at my door
Member Since: Agosto 2, 2007 Posts: 19 Comments: 19234
Quoting Chiggy007:
THERE IS NOTHING ABOUT 91L ON NAVY SITE - QUIT PUTTING FALSE INFO ON HERE PLS


look at post 2613
Member Since: Julio 24, 2005 Posts: 407 Comments: 19076
Quoting DM21Altestic:

Joe Bastardi jizzed in his pants staring at a couple of the northern outliers.
ROFLMAO!!!!!!!!!!!!!!!!!!!!
2634. jipmg
Quoting sammywammybamy:
I have a Decent Question:

IF the Models Runs do hold true.. and IF.. When will South florida be feeling the effects of 02L?

Thank you .... The answer will be used if needed later on to alert friends and family..


02L mid week next week, if it comes to SFLA based on computer models, the other one late weekend.. right before school starts =O

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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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