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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Quoting heliluv2trac:
lets take a poll of 90l

A. gulf storm

b. east coast storm

c. fish storm


To soon to tell lets wait a few more days and then have the poll

Taco :0)
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Quoting WetBankGuy:


If I see ants in the living room tomorrow, it will indicate that the Saints game was exciting enough to scatter food everywhere.


Please do beat the Bungles soundly.
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Quoting heliluv2trac:
lets take a poll of 90l

A. gulf storm

b. east coast storm

c. fish storm


No Polls!!!!!!!!
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Quoting heliluv2trac:
lets take a poll of 90l

A. gulf storm

b. east coast storm

c. fish storm
b
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18Z GFDL

(deleted ... old link) ... WTO
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1428. Patrap
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lets take a poll of 90l

A. gulf storm

b. east coast storm

c. fish storm
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1426. Drakoen
Quoting nrtiwlnvragn:


NHC, they have been putting them out since 06Z.
OFCI is interpolated official.


Okay.
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1425. Keys99
From The Afternoon Key West Forecast Discussion

TONIGHT AND SATURDAY -- THE MOST INTENSE PART OF THE WAVE WILL MOVE
WEST-NORTHWESTWARD VERY NEAR THE FLORIDA KEYS AND SOUTHERN FLORIDA
WITH A DEEPENING MOIST LAYER AND INCREASING SHOWERS AND THUNDERSTORMS
THROUGH THIS EVENING. BY SATURDAY NOON...MOST OF THE KEYS WILL HAVE
RECEIVED MEASURABLE RAINFALL...WITH A FEW LOCATIONS LIKELY REPORTING
MULTIPLE EPISODES. IN ADDITION...FRESHENING SOUTHEASTERLY BREEZES
WILL DEVELOP OVERNIGHT WITH STRONGER SHOWERS AND STORMS PRODUCING
LOCAL GUSTS NEAR GALE FORCE. AFTER 12PM SATURDAY...DRIER AIR ALOFT
WILL BEGIN SLOWLY WORKING IN WITH A GRADUAL DECREASE IN SHOWER AND
THUNDERSTORM COVERAGE EXPECTED.


WEDNESDAY THROUGH FRIDAY -- ANOTHER EASTERLY WAVE MAY BE IN THE
VICINITY BY WEDNESDAY BUT IT IS TOO FAR AWAY TO SPECULATE
INTELLIGENTLY ABOUT EFFECTS ON WIND OR RAIN CHANCES. A DEEP EASTERLY
CURRENT IS EXPECTED TO PERSIST THROUGH LATE WEEK
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1424. Patrap
Any word from those in the know if the new Super computer Cirrus,or Stratus is Handling and Spitting out these clustered results?
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XTRP lol
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I remember thinking that last little jog to the right of Ike changed the destiny of a lot of families.
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Quoting WetBankGuy:


If I see ants in the living room tomorrow, it will indicate that the Saints game was exciting enough to scatter food everywhere.


LMAO!
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Quoting WetBankGuy:


If I see ants in the living room tomorrow, it will indicate that the Saints game was exciting enough to scatter food everywhere.


roflmao

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Quoting Drakoen:
I'm guess the OFCI (official)is based on the HPC or NHC


NHC, they have been putting them out since 06Z.
OFCI is interpolated official.
Member Since: September 23, 2005 Posts: 15 Comments: 11341
The storm is moving west how come the XTRP has it moving West-northwest to Northwest
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1416. WxLogic
18Z NAM showing a little feature moving N along the FL W Coast...
Member Since: August 14, 2008 Posts: 4 Comments: 5038
1415. Patrap
Hiya WetBankGuy,,you heading to the Superdome tonight fer the Festivities?
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Quoting Drakoen:
I'm guess the OFCI (official)is based on the HPC or NHC


The official and the XTRP aren't that far off! Wow those models are very clustered. They may also all be wrong.
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I read an article that said new ants are in the country called raspberry ants which are like huge ant armies - they eat vegetation but leave people alone. Are those the kind of ants you are seeing or the fire ant kind?
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Quoting weathersp:
4:15 and still no HDOB's from NOAA 49


You won't see HDOB from the hight altitude NOAA jet. They will transmit dropsonde information, identified UZNT13 on the Tropical Atlantic site.
Member Since: September 23, 2005 Posts: 15 Comments: 11341
Quoting dcoaster:


Not quite, sir. http://www.time.gov/timezone.cgi?UTC/s/0/java
the time that was done was at 7:17 UTC and now its 20:30 which was over 15 hours ago.
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I overcame my Spanish limitations enough to find a better link to ...

CUBAN RADAR
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Quoting Patrap:
My NOLA ant has been in my Jack again..so He is oblivious as to anything ..



If I see ants in the living room tomorrow, it will indicate that the Saints game was exciting enough to scatter food everywhere.
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Good evening....from South Fla
Interesting the GFS has the 1400 hr update and seems to be staying somewhat consistent with the morning run...The Ensemble run has been updated as well with a 1400 hr run now seeing a shift to the right, is the consensus now shifting right also?
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1407. Drakoen
I'm guess the OFCI (official)is based on the HPC or NHC
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Quoting TropicTraveler:

And I remember Ike was heading right for Corpus Christi and all sorts of plans were made there for rapid response by the disaster agencies. All those plans had to change very quickly when the storm did what it wanted to in the end. Even a couple of days out we don't have a firm idea of where they'll go. I remember Charlie was supposed to hit Tampa and wondering how many more deaths and damage there would have been if it had - and then Ike hit Bolivar instead of straight on into Galvaston - where 20,000 people failed to evacuate. The outcome for them could have been quite different. I guess we all can speculate but in the end we have to wait for these capricious monsters to go where they want to.


Actually, Ike officially made landfall on the eastern end of Galveston Island. Bolivar hit a lot of the headlines because it got the worst of the surge. If Ike made landfall 20 miles west down the coast, the headlines would be about Galveston Island's seawall being topped.
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1405. Patrap
Live and Let Die was a Good un back then for sure..
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Quoting louisianaboy444:
Oh no I saw a black bird this morning.

I saw a black cat this morning could that be a sign that i'm in danger...


Yes, especially if you saw it while walking under a ladder while breaking a mirror.
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1403. Patrap
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Quoting heliluv2trac:
where is your location


Tampa
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Quoting Drakoen:


maintenance


Well that is just bad timing.
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Quoting canesrule1:
no its actually 7:17 UTC which is over 13 hours ago.


Not quite, sir. http://www.time.gov/timezone.cgi?UTC/s/0/java
Quoting dcoaster:


Actually, it's a little under 2.
u have to look at the purple numbers at the buttom of the page, that is the time, the time u r looking at is the buffer time.
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Oh no I saw a black bird this morning.

I saw a black cat this morning could that be a sign that i'm in danger...
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Quoting Patrap:
Beware the Atlantic and Prepare now,to stay ahead of the Game.





Nice scenes of NOLA and STP in that flick...
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Quoting heliluv2trac:
i have seen mounds for the first time this week normally i see black birds before a storm i am still looking for them

Where do you live?
If anyone is to report large ant mounds in umusual spots, we need to know where you live for later verification. Use my blog as the ant blog and leave comments there.
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1394. Drakoen
Quoting CaneWarning:


Why?


maintenance
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where is your location
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Quoting CosmicEvents:

Back when nobody knew where Katrina was going, after reading MaryEsther's comments, I said on these boards throw out all the models and go with the ants. The ants, if used right, can be as good an indicator as any. Again, large mounds in unusual spots.

Happened in our neighborhood before Gustav hit
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Quoting Drakoen:
No more updates from SFWMD until August 17th


Why?
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1390. Drakoen
No more updates from SFWMD until August 17th
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Quoting heliluv2trac:
i have seen mounds for the first time this week normally i see black birds before a storm i am still looking for them


Oh no I saw a black bird this morning.
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Quoting HurricaneKyle:
18:43 UTC Ascending pass.
no its actually 7:17 UTC which is over 13 hours ago.
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Quoting canesrule1:
That quikscat is just over 12 hour old, lol.


Actually, it's a little under 2.
i have seen mounds for the first time this week normally i see black birds before a storm i am still looking for them
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1384. Drakoen
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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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