[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 142343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED DEC 14 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

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

THE MONSOON TROUGH EXTENDS ACROSS AFRICA WITH THE ITCZ ENTERING
THE E TROPICAL ATLC NEAR 9N13W CONTINUING ALONG 9N17W 6N26W
6N40W TO 7N51W. ISOLATED MODERATE CONVECTION IS WITHIN 120 NM
EITHER SIDE OF THE ITCZ BETWEEN 25W-34W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE DOMINATES THE GULF THIS EVENING EXTENDING AND
AXIS FROM THE CARIBBEAN OVER W CUBA ALONG 83W TO OVER THE SE
GULF COAST. THE STRONG SURFACE RIDGE HAS SHIFTED E OVER THE PAST
24 HOURS BUT REMAINS OVER MUCH OF THE GULF AND ANCHORED BY A
1029 MB HIGH OVER E VIRGINIA. STRONG SUBSIDENCE AND DRY STABLE
AIR ALOFT COVERS THE GULF. HOWEVER THE FRESH EASTERLY SURFACE
FLOW COUPLED WITH REMNANT LOW LEVEL MOISTURE IS GIVING A PORTION
OF THE GULF PARTLY CLOUDY SKIES WITH ISOLATED SHOWERS WITHIN
60/75 NM OF LINE FROM 24N80W THROUGH THE STRAITS OF FLORIDA
ALONG 23N88W THEN N TO THE LOUISIANA COAST NEAR 29N91W.
REMARKABLY CLEAR SKIES ARE WITHIN 120 NM ALONG THE COAST OF THE
FLORIDA PENINSULA. SURFACE RIDGE ACROSS THE GULF WILL MOVE E AS
A COLD FRONT WILL MOVE OFF TEXAS THU EXTENDING FROM SW LOUISIANA
TO TAMPICO MEXICO FRI BEFORE STALLING FRI AFTERNOON AND THEN
DISSIPATING SAT. SURFACE RIDGE WILL THEN BUILD N OF THE AREA SUN
MOVING E ON MON.

CARIBBEAN SEA...
AN UPPER TROUGH OVER THE W ATLC DIPS S TO ALONG THE GREATER
ANTILLES SUPPORTING A WEAKENING COLD FRONT THAT ENTERS THE
CARIBBEAN ACROSS N HAITI NEAR 20N72W N OF JAMAICA TO 18N80W.
ISOLATED SHOWERS ARE WITHIN 60 NM SE OF THE FRONT. THE UPPER
LEVELS OF THE CARIBBEAN ARE DOMINATED BY A BROAD UPPER RIDGE
WITH THE AXIS EXTENDING FROM COLOMBIA NEAR 11N74W TO ACROSS W
CUBA INTO THE GULF OF MEXICO. THIS UPPER RIDGE IS DRAWING
TROPICAL MOISTURE N OVER THE S/CENTRAL CARIBBEAN AND COUPLED
WITH THE MONSOON TROUGH THAT EXTENDS FROM COLOMBIA NEAR 11N74W
ALONG 10N77W TO ACROSS PANAMA/COSTA RICA NEAR 10N83W INTO THE E
PACIFIC REGION ARE GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS S OF 12N W OF 72W TO INLAND OVER COLOMBIA TO COSTA
RICA. A SURFACE TROUGH IS ANALYZED FROM THE CENTRAL ATLC INTO
THE E CARIBBEAN OVER GUADELOUPE TO 13N67W WITH SCATTERED SHOWERS
WITHIN 45 NM EITHER SIDE OF THE TROUGH AXIS. THE REMAINDER OF
THE CARIBBEAN IS UNDER MOSTLY FAIR CONDITIONS THIS EVENING WITH
THE POSSIBLE ISOLATED LOW LEVEL SHOWER USHERED IN ON THE
EASTERLY TRADE WINDS. THE COLD FRONT WILL DISSIPATE LATER
TONIGHT. THE SURFACE RIDGE OVER THE GULF OF MEXICO AND SE US IS
PRODUCING FRESH TO STRONG NE TRADE WINDS ACROSS THE NW
CARIBBEAN. THESE CONDITIONS WILL GRADUALLY SHIFT E INTO THE
CENTRAL CARIBBEAN TONIGHT THROUGH THE WEEKEND ENCOMPASSING THE
MOST OF THE CARIBBEAN FRI AND SAT. WINDS WILL DIMINISH IN THE NW
CARIBBEAN THIS WEEKEND AS THE PRESSURE GRADIENT WEAKENS OVER
THAT REGION.

ATLANTIC OCEAN...
A BROAD UPPER TROUGH COVERS THE W ATLC TO THE GREATER ANTILLES
BETWEEN 55W-77W SUPPORTING A COLD FRONT THAT ENTERS THE REGION
NEAR 32N53W ALONG 24N61W TO 20N72W WHERE IT WEAKENS AS IT ENTERS
THE CARIBBEAN. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
WITHIN 120 NM E OF THE FRONT N OF 26N WITH SCATTERED SHOWERS
WITHIN 90 NM SE OF THE REMAINDER OF THE FRONT. STRONG SUBSIDENCE
AND DRY STABLE AIR COVER THE W ATLC W OF THE FRONT GIVING THAT
AREA FAIR CONDITIONS THIS EVENING. A SURFACE TROUGH IS AHEAD OF
THE FRONT EXTENDING FROM 25N57W ALONG 20N58W INTO THE E
CARIBBEAN ACROSS GUADELOUPE WITH SCATTERED SHOWERS WITHIN 60 NM
EITHER SIDE OF THE TROUGH AXIS. BROAD UPPER RIDGE COVERS THE
CENTRAL AND E ATLC ANCHORED NEAR 31N33W PROVIDING DIFFLUENCE
ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
WITHIN 150/175 NM OF LINE FROM 12N51W TO 26N53W. A SURFACE RIDGE
DOMINATES THE E ATLC N OF 20N E OF THE 45W ANCHORED BY A 1030 MB
HIGH E OF THE AZORES. THE COLD FRONT WILL MOVE INTO THE CENTRAL
ATLC LATER THIS EVENING AS THE SURFACE RIDGE BUILDS IN FROM THE
NW. THE RIDGE WILL MOVE SE THROUGH LATE SAT AS ANOTHER COLD
FRONT MOVES INTO THE W ATLC REACHING FROM 31N71W TO THE NORTHERN
BAHAMAS SUN MORNING THEN FROM 31N62W TO THE CENTRAL BAHAMAS LATE
SUN WHILE WEAKENING.

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

$$
PAW





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