[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED DEC 12 2012

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.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS ACROSS AFRICA TO THE COAST OF
LIBERIA. THE ITCZ EXTENDS FROM THE COAST OF LIBERIA NEAR 7N11W
ALONG 5N20W 3N36W TO 4N44W. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 3N TO INLAND OVER SW AFRICA
BETWEEN 2W-5W AND FROM 2N-7N BETWEEN 12W-19W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER TROUGH COVERS THE GULF N OF 25N W OF 84W WITH A
SHORT WAVE UPPER TROUGH MOVING THROUGH MISSISSIPPI TO GEORGIA. A
A BROAD UPPER RIDGE ANCHORED IN THE CARIBBEAN COVERS THE
REMAINDER OF THE GULF INTO THE W ATLC. A STATIONARY FRONT
EXTENDS ACROSS THE GULF FROM AN UPPER TROUGH WELL NE OF THE
DISCUSSION AREA ACROSS FLORIDA FROM DAYTONA BEACH TO TAMPA ALONG
24N88W TO 21N95W THEN S TO 19N95W. SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 90/120 NM NW OF THE
FRONT. A SURFACE TROUGH PRECEDES THE FRONT EXTENDING FROM 24N84W
TO INLAND OVER THE YUCATAN PENINSULA NEAR 21N87W TO NE GUATEMALA
WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 30 NM
EITHER SIDE OF THE TROUGH AXIS. STRONG SUBSIDENCE WITH DRY
STABLE AIR AND CLEAR SKIES ARE W OF A LINE FROM PENSACOLA
FLORIDA ALONG 26N91W TO MATAMOROS MEXICO. STATIONARY FRONT WILL
BEGIN TO MOVE REACHING FROM SW FLORIDA TO THE YUCATAN PENINSULA
THU THEN BECOME DIFFUSE ACROSS STRAITS OF FLORIDA THU NIGHT.
SOUTHERLY RETURN FLOW WILL INCREASE ACROSS THE W GULF FRI NIGHT
THROUGH SUN AHEAD OF THE NEXT COLD FRONT THAT WILL MOVE ACROSS
THE GULF MON AND TUE.

CARIBBEAN SEA...
BROAD UPPER RIDGE COVERS MOST OF THE CARIBBEAN ANCHORED IN THE
SE NEAR 12N79W. A LARGE UPPER TROUGH EXTENDS FROM THE CENTRAL
ATLC OVER THE FAR E CARIBBEAN E OF 66W TO OVER THE LESSER
ANTILLES. A SURFACE TROUGH THAT EXTENDS FROM THE GULF OF MEXICO
TO OVER THE YUCATAN PENINSULA NEAR 21N87W TO NE GUATEMALA IS
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 30 NM
EITHER SIDE OF THE TROUGH AXIS. NE TO E TRADE WINDS ARE USHERING
IN SOME ISOLATED LOW LEVEL SHOWERS ACROSS THE CARIBBEAN S OF 18N
E OF 83W. OTHERWISE THE CARIBBEAN REMAINS TRANQUIL THIS EVENING.
THE STATIONARY FRONT IN THE GULF OF MEXICO WILL ENTER THE FAR NW
CARIBBEAN FRI. FRESH TRADE WINDS ACROSS THE E/CENTRAL CARIBBEAN
WILL DIMINISH THROUGH FRI AS A RIDGE OVER THE ATLC SHIFTS E
AHEAD OF A COLD FRONT MOVING ACROSS THE W ATLC. GENTLE TO
MODERATE TRADE WINDS AND SUBSIDING SEAS WILL PREVAIL ACROSS THE
REGION FRI NIGHT THROUGH TUE.

ATLANTIC OCEAN...
THE UPPER RIDGE IN THE CARIBBEAN EXTENDS AN AXIS INTO THE W ATLC
ACROSS HISPANIOLA TO BEYOND 32N59W. A STATIONARY FRONT FROM AN
UPPER TROUGH WELL NE OF THE DISCUSSION AREA THROUGH 32N76W
ACROSS FLORIDA NEAR DAYTONA BEACH INTO THE GULF OF MEXICO.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS IS WITHIN 90 NM SE OF
THE FRONT AND NW OF THE FRONT TO OVER THE SE CONUS. AN UPPER LOW
IS IN THE CENTRAL ATLC NEAR 22N48W WITH AN UPPER TROUGH
EXTENDING S TO OVER THE SE CARIBBEAN AND THE COAST OF VENEZUELA
NEAR 11N65W SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 17N47W
TO 11N50W. AN UPPER RIDGE TO THE E EXTENDING FROM 12N30W TO
25N37W IS PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 250 NM OF
LINE FROM 25N39W TO 10N48W. A LARGE SURFACE RIDGE DOMINATES THE
ATLC N OF 20N BETWEEN AFRICA AND 75W ANCHORED BY A TRIO OF 1028
MB HIGHS NEAR 31N57W...32N46W...AND 32N37W. A REINFORCING SURGE
OF COOLER AIR WILL PUSH THE STATIONARY FRONT FROM 32N76W TO S
FLORIDA THU MORNING FROM 31N65W TO THE STRAITS OF FLORIDA FRI
MORNING THEN BECOMING DIFFUSE AS A STATIONARY FRONT FRI NIGHT
AND SAT.

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

$$
PAW




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