SW Caribbean Tropical Development? (Is invest 96L)

[crownweather]

Decided to start a new thread to discuss the possibility of tropical development in the southwest Caribbean as early as Saturday. Vorticity seems to be slowly increasing there as convection is currently firing in that region. Not just the Canadian and UKMET models are forecasting development, but the FIM model is also forecasting this possibility. I just posted a full discussion on this potential at http://www.crownweather.com/?page_id=4557

[cycloneye]

Marine forecast.

http://www.nhc.noaa.gov/archive/text/MI ... 200932.txt

MODELS SUGGEST THAT BY LATE FRI THE FRONTAL REMNANTS WILL BEGIN
TO DRIFT W ACROSS THE NW CARIBBEAN SEA INTO MON AS CENTRAL ATLC
HIGH PRES BUILDS SWD...AND LOW PRES BEGINS TO TAKE FORM
OVER THE SW CARIBBEAN AS GLOBAL MODELS SUGGEST. THERE ARE SOME
INDICATIONS THIS MAY ALREADY BE OCCURRING. PRESENTLY...SATELLITE
IMAGERY DEPICTS A LARGE AREA OF NUMEROUS TSTMS COVERING THE
SECTION OF THE CARIBBEAN FROM 14N TO 19N AND W OF 80W PART OF A
BROAD AREA OF LOW PRES. IR ENHANCED NIGHT TIME SATELLITE IMAGERY
SHOWS WHAT APPEARS TO BE A CYCLONIC CIRCULATION ALREADY IN PLACE
ON THE TAIL END OF THE TROUGH NEAR 14N82W. THIS MAY ACTUALLY BE
THE FIRST SIGNS OF LOW PRES FORMING IN THE SW CARIBBEAN SEA AS
VORTICITY IN PLACE INDUCED BY THE NLY FLOW W OF THE FRONT
OPPOSING WLY FLOW S OF 14N PROVIDES THE NECESSARY CYCLONIC SPIN
NECESSARY FOR ORGANIZATION OF THESE CLOUDS AND TSTMS . THIS
ACTIVITY IS ALSO UNDER THE SW PERIPHERY OF AND UPPER LEVEL
ANTICYCLONE PROVIDING VENTILATION ALOFT TO PROLONG TSTM
ACTIVITY...PERHAPS INTO A MORE ORGANIZED SYSTEM IN THE NEAR
FUTURE. IN ADDITION TO MONITORING UPDATED SATELLITE
IMAGERY...WILL ALSO SEE WHAT THE NEXT MODEL RUNS REVEAL WITH
RESPECT TO EXACT TIMING OF GENESIS OF THE LOW AND ITS ASSOCIATED
PRES AND WIND FIELD. AS ANY ORGANIZATION WITH THE BROAD AREA OF
CLOUDS AND TSTMS COULD HAVE SIGNIFICANT IMPACTS OVER PORTIONS OF
THE WESTERN CARIBBEAN WITH RESPECT TO WINDS AND SEAS.

[Blown Away]

TAFB showing our SW Caribbean low now and keeps it stationary for 48 hours. At 72 hours the low begins to move north.
http://www.nhc.noaa.gov/marine_forecasts.shtml

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT THU OCT 20 2011

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

A LARGE AREA OF DISTURBED WEATHER IS CENTERED ABOUT 950 MILES EAST
OF THE SOUTHERN WINDWARD ISLANDS. THIS SYSTEM IS EXPECTED TO MOVE
SLOWLY WESTWARD WITH A LOW CHANCE...10 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

CLOUDINESS AND SHOWERS HAVE INCREASED IN THE WESTERN CARIBBEAN SEA.
SURFACE PRESSURES ARE NOT FALLING AT THIS TIME AND DEVELOPMENT...IF
ANY...WILL BE SLOW TO OCCUR. THIS SYSTEM IS EXPECTED TO MOVE LITTLE
AND HAS A LOW CHANCE...10 PERCENT...OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS.

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

$$
FORECASTER AVILA

[SFLcane]

Season not over just yet..

NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 36 HOURS

FORECAST POSITION AT T+ 36 : 13.4N 80.8W

[wxman57]

Note that all the models, whether they take the low into CA (GFS/Euro) or not (Canadian/UK) have WSW-SW winds of 50-70 kts across the southern Gulf and south Florida by early next week. So if the low was to get picked up and taken northward, it would encounter some quite strong shear after leaving the Caribbean. I'd think a westerly motion would be more likely - into Central America and/or southern MX by a weaker system.

[cycloneye]

This afternoon's discussion of this area by Dr Jeff Masters:

A large area of disturbed weather in the Western Caribbean is bringing heavy rains to coastal Nicaragua and Honduras. The heavy thunderstorms are in an area of weak steering currents, and will move little over the next two days. Wind shear is a high 20 - 30 knots in the region, but is expected to drop to the moderate range on Friday, and remain moderate through the weekend. This should allow some slow development of the disturbance, and the GFS, UKMET, and NOGAPS models all develop the disturbance into a tropical depression by Monday. The most likely areas to be affected by this hypothetical storm are Honduras and Nicaragua, but we can't rule out a scenario where the storm moves northwards and threatens Cuba late next week, as the UKMET model is predicting. NHC gave the disturbance a 10% chance of developing into a tropical depression by Sunday in their 8 am Tropical Weather Outlook.

[CourierPR]

If there is a threat to Cuba late next week, then upper level winds could relax by then.

[cycloneye]

2 PM TWO=Up to 20%:

CLOUDINESS AND SHOWERS OVER THE WESTERN CARIBBEAN SEA ARE ASSOCIATED
WITH A BROAD AREA OF LOW PRESSURE CENTERED BETWEEN THE EASTERN TIP
OF HONDURAS AND JAMAICA. ALTHOUGH SURFACE PRESSURES ARE NOT FALLING
AT THIS TIME...ENVIRONMENTAL CONDITION ARE FAVORABLE FOR SLOW
DEVELOPMENT. THIS SYSTEM IS EXPECTED TO MOVE LITTLE AND HAS A LOW
CHANCE...20 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

[cycloneye]

12z UKMET:

NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 24 HOURS

FORECAST POSITION AT T+ 24 : 12.7N 81.1W



VERIFYING TIME POSITION STRENGTH TENDENCY

-------------- -------- -------- --------

12UTC 21.10.2011 12.7N 81.1W WEAK

00UTC 22.10.2011 12.9N 80.9W WEAK WEAKENING SLIGHTLY

12UTC 22.10.2011 12.4N 80.6W WEAK LITTLE CHANGE

00UTC 23.10.2011 14.1N 80.8W WEAK LITTLE CHANGE

12UTC 23.10.2011 15.1N 81.0W WEAK LITTLE CHANGE

00UTC 24.10.2011 16.3N 81.3W MODERATE INTENSIFYING SLIGHTLY

12UTC 24.10.2011 17.4N 81.3W MODERATE INTENSIFYING SLIGHTLY

00UTC 25.10.2011 18.4N 81.4W MODERATE LITTLE CHANGE

12UTC 25.10.2011 19.6N 81.8W STRONG INTENSIFYING SLIGHTLY

00UTC 26.10.2011 21.0N 81.7W STRONG INTENSIFYING SLIGHTLY

12UTC 26.10.2011 22.2N 82.1W STRONG WEAKENING SLIGHTLY

[CrazyC83]

This looks like a classic late October system. Will it manage to hide from the two intense fronts then just tuck behind them or will they just scoop this out?

Should be 96L soon anyway.

[tolakram]

Live visible loop: http://wwwghcc.msfc.nasa.gov/cgi-bin/ge ... umframes=5

[cycloneye]

HPC extended range forecast:

CMC AND UKMET ALONG WITH A CONSIDERABLE NUMBER OF ECMWF ENS
MEMBERS INDICATE THE POTENTIAL OF TROPICAL DEVELOPMENT IN THE NWRN
CARRIBEAN NEXT WEEK. HAVE ADJUSTED SFC PROGS FOR THIS FEATURE
SLOWER THAN THE OPERATIONAL CMC AND UKMET APPROACHING WRN
CUBA/YUCATAN CHANNEL MID NEXT WEEK.

HPC UPDATED PROGS USE A MIXTURE OF 00Z ECMWF/00Z GFS AND 00Z ECMWF
ENS MEANS DAYS 3-5 SUN-TUES AND 00Z ECMWF ENS MEAN DAYS 6-7
WED/THURS. SOME FRONTAL CHANGE ADJUSTMENTS MADE TO AFTN FINALS
WITH A SLOWER FRONT THRU THE SRN PLAINS AND APPROACHING THE
APPLCHNS DAY 7 THURS WITH ADDITIONAL ATTENTION MADE TO THE
POSSIBLE TROPICAL SYSTEM DEVELOPMENT AND THREAT TO THE WRN
CARRIBEAN.

ROSENSTEIN

[wxman57]

That HPC 7-day surface map looks most similar to the Canadian as far as position & timing, maybe a bit slower than the Canadian. Of course, the Canadian goes nuts as far as intensity. There's a chance it could track slowly northward, but even the Canadian has some quite strong westerly winds across the southern Gulf and south Florida by the middle of next week. Any storm moving out of the Caribbean next week would immediately move into quite a hostile environment.

Of course, the GFS model could be correct as well, taking a weak system westward into Central America early next week.

I'd say development chances (TS) are in the 60% range, with development most likely on Sunday rather than as early as Saturday (as some models forecast). With development now supported by all models except the Euro, and with a prime setup for development down there in place (storms developing on trailing end of cold front), it's hard to deny that development isn't more likely than not. I think you'll see the NHC slowly ramping up the chance of development as their 48hr development period extends into Sunday tomorrow.

[psyclone]

a michelle (2001 i think?) type track (not necesarily intensity) would seem a reasonable solution on this one.

[wxman57]

a michelle (2001 i think?) type track (not necessarily intensity) would seem a reasonable solution on this one.

It's possible, or it could get a little closer to Florida.

[SouthDadeFish]

It looks like a surface low is trying to develop in this area:



Still fairly broad at this time.

[cycloneye]

The TAFB 18z surface analysis has added a low pressure.

[Macrocane]

According to the models this will develop pretty soon, the only global that makes nothing with it is the ECMWF (it has only a trough), the rest of them has at least a tropical depression in 48 hours:

[cycloneye]

8 PM TWO:

A BROAD LOW PRESSURE AREA IS LOCATED OVER THE WEST-CENTRAL CARIBBEAN
SEA ABOUT 150 MILES EAST OF THE HONDURAS-NICARAGUA BORDER. ALTHOUGH
THIS LARGE DISTURBANCE IS SHOWING SOME SIGNS OF ORGANIZATION...ANY
FURTHER DEVELOPMENT SHOULD BE SLOW TO OCCUR DUE TO MARGINALLY
FAVORABLE UPPER-LEVEL WINDS AND PROXIMITY TO DRY AIR. THIS SYSTEM
HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS AS IT MOVES LITTLE OR DRIFTS SLOWLY
SOUTHWARD.