[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 132354
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU DEC 13 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 MOST OF AFRICA. THE ITCZ
EXTENDS FROM OVER LIBERIA INTO THE E TROPICAL ATLC NEAR 6N10W
ALONG 4N18W 3N30W TO 3N41W. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 4N-8N BETWEEN 12W-16W...
FROM 1N-5N BETWEEN 15W-39W...AND FROM 5N-9N BETWEEN 37W-45W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD LOW AMPLITUDE UPPER TROUGH COVERS THE GULF N OF 26N AND
INTO THE W ATLC SUPPORTING A COLD FRONT THAT AT 13/2100 UTC
EXTENDS THROUGH THE STRAITS OF FLORIDA NEAR 25N80W JUST S OF THE
FLORIDA KEYS TO 23N84W WHERE IT DISSIPATES ALONG THE N COAST OF
THE YUCATAN TO 21N93W AND CONTINUES DISSIPATING AS A STATIONARY
FRONT ALONG 21N95W TO THE COAST OF MEXICO NEAR THE ISTHMUS OF
TEHUANTEPEC. SCATTERED SHOWERS ARE WITHIN 30 NM ALONG THE FRONT
E OF 82W. STRONG SUBSIDENCE WITH DRY STABLE AIR AND MOSTLY CLEAR
SKIES ARE N OF A LINE FROM TAMPA FLORIDA TO CORPUS CHRISTI TEXAS
WITH THE EXCEPTION OF OVERCAST LOW CLOUDS N OF 27N W OF 85W TO
OVER NE FLORIDA. A BROAD UPPER RIDGE ANCHORED IN THE E PACIFIC
REGION COVERS THE REMAINDER OF THE GULF. A SURFACE RIDGE IS
BUILDING S OVER THE GULF BEHIND THE FRONT ANCHORED BY A 1030 MB
HIGH OVER TENNESSEE. COLD FRONT WILL BECOME STATIONARY TONIGHT
THEN DISSIPATE ACROSS THE STRAITS OF FLORIDA FRI. SOUTHERLY
RETURN FLOW WILL INCREASE ACROSS THE W GULF FRI NIGHT THROUGH
LATE SUN AHEAD OF THE NEXT COLD FRONT THAT WILL MOVE ACROSS THE
GULF MON AND TUE.

CARIBBEAN SEA...
BROAD UPPER RIDGE COVERS THE W CARIBBEAN W OF 70W ANCHORED IN
THE E PACIFIC REGION. A LARGE UPPER TROUGH EXTENDS FROM AN UPPER
LOW IN THE W TROPICAL ATLC OVER THE REMAINDER OF THE CARIBBEAN.
NE TRADE WINDS ARE USHERING IN SOME ISOLATED LOW LEVEL SHOWERS
MAINLY N OF 15N E OF 69W AND S OF 16N BETWEEN 74W-83W. OTHERWISE
THE CARIBBEAN REMAINS TRANQUIL THIS EVENING. THE COLD FRONT IN
GULF OF MEXICO WILL REACH THE NW CARIBBEAN FRI. FRESH TRADE
WINDS ACROSS E/CENTRAL CARIBBEAN WILL DIMINISH THROUGH FRI AS A
SURFACE RIDGE OVER THE ATLC WATERS SHIFTS E AHEAD OF THE NEXT
COLD FRONT THAT WILL MOVE INTO THE W ATLC TUE.

ATLANTIC OCEAN...
A BROAD LOW AMPLITUDE UPPER TROUGH COVERS THE W ATLC N OF 26N W
OF 70W SUPPORTING A COLD FRONT THAT AT 13/2100 UTC EXTENDS
THROUGH 32N70W ACROSS THE N BAHAMA ISLANDS TO THE STRAITS OF
FLORIDA INTO THE GULF OF MEXICO NEAR 25N80W. SCATTERED SHOWERS
ARE WITHIN 30/45 NM SE OF THE FRONT. AN UPPER LOW IS IN W
TROPICAL ATLC NEAR 19N50W WITH AN UPPER TROUGH COVERING THE AREA
FROM 10N-25N BETWEEN 45W-70W. SCATTERED SHOWERS/THUNDERSTORMS
ARE ASSOCIATED WITH THE UPPER LOW COVERING THE AREA FROM 18N-22N
BETWEEN 48W-51W. A SURFACE TROUGH IS SE OF THE UPPER LOW
EXTENDING FROM 19N45W TO 10N49W. A UPPER RIDGE TO THE E IS
PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS WITHIN 200 NM E OF THE SURFACE
TROUGH. A LARGE SURFACE RIDGE DOMINATES THE ATLC N OF 20N
BETWEEN AFRICA AND 60W ANCHORED BY A 1023 MB HIGH NEAR 30N33W. W
ATLC COLD FRONT WILL REACH FROM 32N64W TO THE STRAITS OF FLORIDA
FRI THEN DISSIPATE FRI NIGHT AND SAT. THE NEXT COLD FRONT WILL
MOVE INTO THE W ATLC TUE.

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

$$
PAW





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