[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI OCT 21 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1730 UTC.

...SPECIAL FEATURE...

A NEARLY STATIONARY 1008 MB LOW IS OVER THE SW CARIBBEAN NEAR
13N80W. THIS SYSTEM IS INTERACTING WITH A WEAK STATIONARY FRONT
TO ITS N...AND MONSOONAL FLOW TO ITS S. THIS COMPLEX SCENARIO
IS GENERATING A BROAD AREA OF SCATTERED HEAVY SHOWERS AND
THUNDERSTORMS W OF 79W. THE ASSOCIATED SHOWER ACTIVITY HAS
BECOME BETTER ORGANIZED...AND THERE IS A LIKELIHOOD THAT A
TROPICAL DEPRESSION WILL FORM DURING THE WEEKEND. LITTLE MOTION
IS ANTICIPATED IN THE SHORT TERM...BUT A SLOW NORTHWARD DRIFT
SHOULD BEGIN ON SUNDAY. THIS SYSTEM HAS A HIGH OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 14N17W TO 5N27W. A SMALL SECTION OF THE ITCZ DEVELOP
THIS MORNING AND WAS ANALYZED FROM 5N27W TO NEAR 5N37W.
SCATTERED MODERATE CONVECTION IS FROM 3N-20N E OF 27W. A BROAD
AREA OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS
AFFECTING THE COASTAL WATERS OF GUYANA...SURINAME...FRENCH
GUIANA S OF 12N BETWEEN 48W-60W. A SURFACE TROUGH IS ANALYZED
WITHIN THIS REGION FROM 13N53W TO INLAND OVER FAR NE GUYANA NEAR
8N60W. THIS AREA OF CONVECTION WILL LIKELY SPREAD OVER NRN
VENEZUELA AND THE SRN WINDWARD ISLANDS DURING THE NEXT FEW DAYS.

...DISCUSSION...

GULF OF MEXICO...
A COOL AND DRY AIRMASS CONTINUES TO DOMINATE THE WATERS ACROSS
THE GULF THIS AFTERNOON. BROAD SURFACE ANTICYCLONIC FLOW COVERS
THE AREA. AS THIS AIRMASS SPREADS OVER THE WARM WATERS OF THE
GULF...LOW LEVEL STRATOCUMULUS CLOUDS DEVELOP OVER MOST AREAS...
EXCEPT THE CENTRAL AND NRN GULF. IN THE UPPER LEVELS OF THE
ATMOSPHERE...STRONG SUBSIDENCE ALOFT COVERS THE ENTIRE GULF
SUPPORTING THE FAIR WEATHER ENVIRONMENT ACROSS THE AREA.
CONDITIONS ARE EXPECTED TO REMAIN CONSTANT OVER THE NEXT 24
HOURS. SURFACE RIDGE WILL CONTINUE TO BUILD ACROSS THE WRN GULF
THROUGH TUESDAY.

CARIBBEAN SEA...
CLUSTERS OF HEAVY SHOWERS AND THUNDERSTORMS CONTINUE TO AFFECT
THE NW AND SW BASINS OF THE CARIBBEAN SEA W OF 79W...ASSOCIATED
TO THE STATIONARY FRONT EXTENDING ALONG CENTRAL CUBA TO THE ERN
COAST OF HONDURAS...AND THE SPECIAL FEATURE LOW PRESSURE SYSTEM
LINGERING OVER THE SW BASIN NEAR 13N80W. SHORT RANGE COMPUTER
MODELS SUGGEST THE CONVECTION IN THIS REGION WILL LINGER OVER
THE NEXT 24 HOURS. ENE TRADE WIND FLOW IS CONVERGING WITH
MONSOONAL FLOW COMING FROM NRN SOUTH AMERICA...GENERATING A
SCATTERED SHOWERS WITHIN 100 NM OFF THE COAST OF COLOMBIA AND
VENEZUELA. OTHERWISE...FAIR WEATHER CONDITIONS PREVAIL ELSEWHERE
ACROSS THE AREA...AS A BROAD UPPER CYCLONE IN  THE SW ATLC DRAWS
DRY AND SUBSIDENT AIR ALOFT SUPPRESSING DEEP CONVECTION ACROSS
THE AREA.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH IS SLOWLY MOVING OFF THE ERN CONUS SEABOARD
SUPPORTING A STATIONARY FRONT ANALYZED ACROSS THE THE WRN ATLC
ALONG 31N70W TO ACROSS THE CENTRAL BAHAMAS NEAR LONG ISLAND INTO
THE CARIBBEAN ACROSS CENTRAL CUBA ALONG CAMAGUEY. SCATTERED
MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS ARE WITHIN 60 NM ON
EITHER SIDE OF THE BOUNDARY. AS THE UPPER LEVEL TROUGH PUSHES
EASTWARD...THE FRONT AND ASSOCIATED CONVECTION IS EXPECTED TO
CONTINUE TO SLOWLY PROGRESS ENE DURING THE NEXT 24 HOURS. AN
UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED 22N60W. THIS
CIRCULATION IS MOVING W-SW WITH WIDELY SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS FROM 19N-25N BETWEEN 53W-64W. AN AREA OF
BROAD ELONGATED TROUGHINESS AND LOWER PRESSURES IS IN THE
CENTRAL TROPICAL ATLC ANALYZED AS A SURFACE TROUGH EXTENDING SW
FROM A 1013 MB LOW NEAR 20N37W TO A SECOND 1008 MB LOW NEAR
16N44W THEN SOUTHWARD TO 11N46W. DESPITE THE LOCATION OF THIS
SYSTEM...BROAD AREA OF DIFFLUENCE IN THE MID AND UPPER LEVELS IS
DISPLACING THE CONVECTION WELL NE OF THE ANALYZED FEATURE FROM
21N-27N BETWEEN 20W-35W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

GARCIA



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