[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211736
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI DEC 21 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...ITCZ/MONSOON TROUGH...

THERE IS CURRENTLY NO PORTION OF THE MONSOON TROUGH OVER THE
ATLC WATERS. THE ITCZ BEGINS OVER LAND AND CONTINUES TO THE
COAST OF LIBERIA NEAR 7N11W EMERGING OVER WATER ALONG 8N20W
5N30W 2N53W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
FROM 3N-6N BETWEEN 30W-42W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER TROUGH CONTINUES TO COVER THE EASTERN CONUS
EXTENDING INTO THE GULF OF MEXICO SUPPORTING A STRONG COLD FRONT
WHICH HAS MOSTLY MOVED EAST OF THE BASIN. AS OF 1500 UTC...THE
FRONT HAS PUSHED SE OF FLORIDA INTO THE NW CARIBBEAN CONTINUING
ACROSS THE YUCATAN PENINSULA INTO SOUTHERN MEXICO. A
DRY...COOL...AND STABLE AIRMASS IS LEFT IN ITS WAKE PROVIDING
CLEAR SKIES ACROSS FLORIDA AND THE NORTHERN GULF. SOME FAIR
WEATHER STRATOCUMULUS CLOUDS COVER THE SOUTHERN
GULF...ESPECIALLY THE BAY OF CAMPECHE. GALE FORCE WINDS ALSO
CONTINUE IN THE SW GULF...BUT ARE EXPECTED TO DIMINISH BELOW
GALE FORCE BY 1800 UTC. STRONG NW WINDS SPREAD OVER THE
REMAINDER OF THE BASIN REACHING 20-25 KT. SURFACE HIGH PRESSURE
IS BEGINNING TO BUILD IN ACROSS THE GULF BEHIND THE FRONT
CURRENTLY ANCHORED BY A 1033 MB HIGH OVER SOUTHERN TEXAS. THE
RIDGE IS EXPECTED TO SHIFT EAST OVER THE NEXT FEW DAYS BEFORE
ANOTHER FRONT ENTERS THE NW GULF IN THE MIDDLE OF NEXT WEEK.

CARIBBEAN SEA...
MOSTLY DRY AIR ALOFT COVERS THE CARIBBEAN AROUND A SMALL UPPER
RIDGE AXIS EXTENDING FROM THE YUCATAN PENINSULA TO CENTRAL CUBA
WITH ZONAL WESTERLY FLOW COVERING THE REMAINDER OF THE BASIN.
THIS DRY AIR IS PROVIDING MOSTLY FAIR CONDITIONS BASIN-WIDE.
HOWEVER...A FEW AREAS OF SHOWER ACTIVITY ARE PRESENT. A LINE OF
POSSIBLE SHOWERS IS IN THE NW CARIBBEAN ASSOCIATED WITH THE COLD
FRONT THAT HAS PUSHED THROUGH THE GULF OF MEXICO DURING THE PAST
DAY AND NOW EXTENDS FROM WESTERN CUBA TO THE YUCATAN PENINSULA.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE IN THE SW CARIBBEAN
ALONG THE COASTS OF NICARAGUA...COSTA RICA...AND PANAMA DUE TO
WIND CONVERGENCE AS 20-25 KT WINDS HIT THE COAST. FINALLY...AN
AREA OF SHOWERS/ISOLATED THUNDERSTORMS IS MOVING THROUGH THE
SOUTHERN WINDWARD ISLANDS SOUTH OF 14N WESTWARD TO 67W.
TRADEWIND FLOW OF 15-20 KT IS PRESENT ACROSS THE MAJORITY OF THE
AREA REACHING 25 KT NEAR THE COAST OF COLOMBIA. EXPECT THE FRONT
IN THE NW CARIBBEAN TO CONTINUE TO PUSH SE WITH STRONG NORTH
WINDS UP TO 25 KT BEHIND IT.

ATLANTIC OCEAN...
A STRONG COLD FRONT IS PUSHING THROUGH THE WEST ATLC SUPPORTED
BY A DEEP LAYER TROUGH OVER THE EASTERN CONUS. AS OF 1500
UTC...THE FRONT ENTERS THE DISCUSSION AREA NEAR 32N73W
CONTINUING TO THE BAHAMAS AT 27N78W TO CUBA AT 23N82W. A LINE OF
SHOWERS/THUNDERSTORMS IS ALONG THE FRONT AXIS WITH ISOLATED
SHOWERS WITHIN 60 NM. GALE FORCE WINDS ARE BOTH EAST AND WEST OF
THE FRONT NORTH OF 3ON. WEAK SURFACE RIDGING IS TO THE EAST
AROUND A 1018 MB HIGH NEAR 28N66W. THE HIGH IS SUPPORTED BY AN
UPPER LEVEL RIDGE ALONG 63W. A SECOND DEEP LAYER TROUGH IS
IMPACTING THE CENTRAL ATLC ALONG 45W SUPPORTING A COLD FRONT
ENTERING THE AREA NEAR 32N37W AND CONTINUING ALONG 23N47W 19N61W
AND DISSIPATING TO 19N68W. ISOLATED SHOWERS ARE ALONG THE AXIS.
GALE FORCE WINDS ARE WEST OF THE FRONT N OF 29N. A PRE-FRONTAL
SURFACE TROUGH IS EAST OF THE FRONT ALONG 31N37W 23N43W 18N51W.
SCATTERED SHOWERS ARE WITHIN 100 NM E OF THE AXIS. THE REMAINDER
OF THE EAST ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1028
MB HIGH SW OF PORTUGAL. THE SURFACE RIDGE IS SUPPORTED BY AN
UPPER LEVEL RIDGE ALONG 12W.

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

$$
WALTON






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