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 thelmores:
Would like to point out it is somewhat rare for a land falling cane on east of Florida..... doesn't mean it won't happen, but I think the models could shift a little from their final resolution...... shift left or right?


C'mon Thel!!! What's wrong with you?! You know JFVWS doesn't want to hear that...
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4583. jipmg
Ana's center is now exposed
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Yeah, Navy has 03L.THREE.
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Quoting cardinal56:
anyone know where to buy an F5 key?? after last nights craziness i need a new one. and probably a lot of others on this blog lol


and to think i discovered f5 after justin.tv ...
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4579. JRRP
yes
TD3
Link
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4578. geepy86
Anybody think that little swirl by the keys might be one of those "pop-up" close to land storms that Dr. Masters was talking about early in the season.
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Morning All

15/1145 UTC 11.4N 33.5W T2.5/2.5 90L -- Atlantic

TD3 is born. Most likely will be Bill very soon with those numbers.
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Quoting FLHurricaneChaser:
It's official!


BEGIN
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woo hoo.

Any idea what intensity?
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I think in Puerto Rico we will be lucky and blessed once more and we won't get any oo these storms.. It has been so since 2004, when Jeanne threw a couple of inches of rain.
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Quoting IKE:


Has a nice vorticity....



It is also well vertically stacked, vorticity extends all the way at 500mb.
Member Since: July 19, 2008 Posts: 43 Comments: 4051
As expected, the warm waters of the Atlantic and the ITCZ have combined to form Ana in the first half of August.
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Quoting 7544:
oh 90l off navy page maybe changing the name no w stay tu2009 Storms
All Active Year

Atlantic
02L.ANA

I was just about to comment on that.
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4569. jipmg
wow our low is looking like a tropical storm
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Would like to point out it is somewhat rare for a land falling cane on east of Florida..... doesn't mean it won't happen, but I think the models could shift a little from their final resolution...... shift left or right?
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Quoting hurricanelover236:

I am a young meteorologist who has been studying hurricanes and made accurate predictions about hurricanes past and this current season. I am rarely wrong when it comes to hurricanes.

From your own words --
3. hurricanelover236 4:54 PM GMT on August 14, 2008 "no i live in florida 2. Hurricanes are fun plus no school."

I wonder what your motivation is for this one? Has school not started yet?
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Quoting seflagamma:
did they just make 90L TD3?


Looks like it, yes.
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4565. ackee
seem like WE may SEE TD#3 possble at 11am or before
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navy site says 03L THREE
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Quoting geepy86:
Anybody think that little swirl by the keys might be one of those "pop-up" close to land storms that Dr. Masters talked about early in the season?


Dr. Lyons on the Tropical Update (7:51 am) said that there wasn't anything to worry about with that wave?
We'll see.
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4562. jipmg
Quoting HurricaneKyle:
Subject to change, but I'll call it TD3 in the mean time just because they ran it at 30 kts.


TWC says they found a 40mph wind in our low
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i agree with the models consensus of ana and bill taking the route nw however the longer they continue the westward track the more likely it will take it or them through the caribbean, the high above them is not moving and if it is it is slow,also the ull just east of florida will play a major role in direction as it continues on it path to the sse.
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4560. hahaguy
Quoting AussieStorm:

That has Ana dissipating. Isn't Fla ment to get Ana as a TS?


That's what it looks like so far.
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Quoting snotly:


or if really want to have fun here on this blog ask STORMTOP about tunnels and OTEC

I miss STORMTOP

http://en.wikipedia.org/wiki/OTEC


i miss stormtop too ! if every storm that he predicted actually happened.i wouldnt be here !thats why i"m "stormbottom" !
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4558. IKE
Quoting geepy86:
Anybody think that little swirl by the keys might be one of those "pop-up" close to land storms that Dr. Masters talked about early in the season?


Has a nice vorticity....

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did they just make 90L TD3?
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lol olny 500 more commets too go whats see if we can make it
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4555. 7544
oh 90l off navy page maybe changing the name no w stay tu2009 Storms
All Active Year

Atlantic
02L.ANA





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anyone know where to buy an F5 key?? after last nights craziness i need a new one. and probably a lot of others on this blog lol
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Quoting CrazyDuke:


Wow, that looks more like a sick joke.

That has Ana dissipating. Isn't Fla ment to get Ana as a TS?
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Subject to change, but I'll call it TD3 in the mean time just because they ran it at 30 kts.
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000
WHXX01 KWBC 151248
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1248 UTC SAT AUG 15 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE ANA (AL022009) 20090815 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090815 1200 090816 0000 090816 1200 090817 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 14.3N 47.6W 15.2N 50.8W 16.6N 55.0W 18.4N 59.4W
BAMD 14.3N 47.6W 15.2N 50.3W 16.1N 53.5W 17.0N 57.1W
BAMM 14.3N 47.6W 15.0N 50.4W 15.7N 54.0W 16.5N 57.9W
LBAR 14.3N 47.6W 14.7N 50.4W 15.4N 53.7W 16.3N 57.3W
SHIP 35KTS 39KTS 43KTS 47KTS
DSHP 35KTS 39KTS 43KTS 47KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090817 1200 090818 1200 090819 1200 090820 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 20.2N 64.1W 23.7N 71.5W 26.6N 76.2W 28.4N 79.1W
BAMD 17.8N 60.9W 19.5N 68.7W 21.6N 75.1W 23.2N 79.3W
BAMM 17.3N 62.2W 19.1N 70.4W 20.9N 77.6W 22.4N 82.7W
LBAR 17.0N 61.1W 18.7N 68.8W .0N .0W .0N .0W
SHIP 53KTS 62KTS 62KTS 66KTS
DSHP 53KTS 62KTS 62KTS 66KTS

...INITIAL CONDITIONS...
LATCUR = 14.3N LONCUR = 47.6W DIRCUR = 265DEG SPDCUR = 14KT
LATM12 = 14.5N LONM12 = 44.8W DIRM12 = 268DEG SPDM12 = 14KT
LATM24 = 14.6N LONM24 = 41.8W
WNDCUR = 35KT RMAXWD = 40NM WNDM12 = 30KT
CENPRS = 1005MB OUTPRS = 1010MB OUTRAD = 150NM SDEPTH = M
RD34NE = 60NM RD34SE = 0NM RD34SW = 0NM RD34NW = 60NM

$$
NNNN

SHIPs takes ANA to hurricane status.
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4549. Prgal
000
FLCA42 TJSJ 151235
HWOSJU

HAZARDOUS WEATHER OUTLOOK FOR PUERTO RICO AND THE U.S. VIRGIN
ISLANDS
NATIONAL WEATHER SERVICE SAN JUAN PR
835 AM AST SAT AUG 15 2009

AMZ710>745-PRZ001>013-161000-
SAN JUAN AND VICINITY-NORTHEAST-SOUTHEAST-EASTERN INTERIOR-
NORTH CENTRAL-CENTRAL INTERIOR-PONCE AND VICINITY-NORTHWEST-
WESTERN INTERIOR-MAYAGUEZ AND VICINITY-SOUTHWEST-CULEBRA-VIEQUES-
THE NEARSHORE AND OFF SHORE ATLANTIC AND CARIBBEAN COASTAL WATERS-
835 AM AST SAT AUG 15 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO AND THE
ADJACENT COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

TROPICAL STORM ANA MAY AFFECT THE AREA MONDAY AND MONDAY NIGHT.

ANOTHER AREA OF LOW PRESSURE ABOUT 600 MILES TO THE WEST SOUTHWEST
OF THE CAPE VERDE ISLANDS CONTINUES TO BECOME BETTER
ORGANIZED...AND A TROPICAL DEPRESSION MAY BE FORMING. ADVISORIES
WILL LIKELY BE INITIATED LATER TODAY.

INTERESTS IN PUERTO RICO ARE ENCOURAGED TO MONITOR LATEST
FORECASTS FROM THE NATIONAL HURRICANE CENTER.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT.

$$
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4548. geepy86
Anybody think that little swirl by the keys might be one of those "pop-up" close to land storms that Dr. Masters talked about early in the season?
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4547. SQUAWK
Quoting IKE:


Upgrade imminent.


Ike, I seem to remember that a couple of weeks ago you said that we would be 0,0,0 until the 15th of August. Looks like you hit the nail on the head. WTG!!! No crow for Ike!!!!
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I hate to say this but I think both these storms will get into the Caribbean.
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Subject to change of course, as they often do, but the latest message as AL032009 running at 30kts, not 35kts.

If that remains, it'll be TD3 and not Bill. Just yet.
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O, and i have been really surprised they have not upgraded 90L as of yet. It looks very healthy. This has to be Bill at 11 am, if not i will be very surprised.
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Quoting Tazmanian:



can i have a link


ATCF
Member Since: September 23, 2005 Posts: 14 Comments: 11162
TD 3 or bill do we have????
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Wonder if they made it TD3 or Bill.
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4540. KBH
Quoting snotly:


http://en.wikipedia.org/wiki/Project_Stormfury

Thanks Snotly, very informative. I coul see why Storm fury was deema failure, not suffient analysis before and after implementation. I mean waiting a day before the storm/ hurricane is due to hit land is rediculous. I have a hypothesis ... would a few tonnes of saharan african dust at the source of origin do any good?
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If it walks.... and quacks.... and looks..... like a TD...... must be one! LOL

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Remember, Ana and 90L are still a good distance out there... The State of Florida has a very good interactive family preparedness worksheet online...

http://www.floridadisaster.org/family/

If you don't have a plan yet, now's a great time to get one...
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Quoting WeatherStudent:
7,000 posts during Wilma, Pressy.



no there was not


dr m blog was vary new back at that time
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It's official!


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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.