[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 311730
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI DEC 31 2010

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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

THE ITCZ AXIS IS ANALYZED FROM THE COAST LIBERIA NEAR 05N09W
WESTWARD ALONG 2N20W 3N30W 2N40W EQ50W. CLUSTERS OF SCATTERED
WEAK CONVECTION ARE FROM THE EQUATOR TO 06N BETWEEN 24W AND 38W.
SCATTERED MODERATE CONVECTION IS WITHIN 100 NM OFF THE COAST OF
LIBERIA AND COTE D'IVOIRE BETWEEN 4W AND 10W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES DRY SW FLOW ALOFT ACROSS THE
BASIN...WITH AN UPPER LEVEL LONGWAVE MOVING NE ACROSS SOUTHERN
TEXAS AND CENTRAL ARKANSAS. THIS FEATURE SUPPORTS THE NEXT COLD
FRONT CURRENTLY OVER SE TEXAS AND SOON TO TO ENTER THE NW GULF
WATERS OVER THE NEXT FEW HOURS. SATELLITE DERIVED WINDS AND SFC
OBS ACROSS THE GULF INDICATE 15 KT TO 25 KT RETURN FLOW OVER
MOST OF THE WESTERN HALF OF THE BASIN W OF 90W...BECOMING NEAR
GALE FORCE RETURN FLOW N OF 25N BETWEEN 87W AND 92W. MOSTLY SSE
FLOW IS OBSERVED E OF 90W DUE TO ANTI-CYCLONIC FLOW AROUND THE
1025 MB HIGH OVER THE WESTERN ATLC. THIS SCENARIO IS ADVECTING A
WARM AND MOIST AIRMASS ACROSS THE N CENTRAL BASIN N OF 25N
BETWEEN 85W AND 95W. IN RESPONSE...MOSAIC DOPPLER RADAR IMAGERY
INDICATES SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS QUICKLY
MOVING INLAND INTO LOUISIANA...MISSISSIPPI...AND ALABAMA
BETWEEN 87W AND 92W. THE REMAINDER OF THE GULF IS UNDER MOSTLY
CLEAR SKIES THIS AFTERNOON. EXPECT CONVECTION TO CONTINUE TO
DEVELOP ACROSS MOST OF THE GULF...AHEAD OF THE COLD FRONT IN THE
NEXT 24 HOURS.

CARIBBEAN SEA...
THE SURFACE RIDGE OVER THE W ATLC COVERS A GREAT PORTION OF THE
NORTHERN HALF OF THE CARIBBEAN PROVIDING 15-20 KT ANTI-CYCLONIC
FLOW N OF 14N. A DISSIPATING STATIONARY FRONT EXTENDS ACROSS THE
CENTRAL ATLC...ENTERING THE EASTERN CARIBBEAN AS A REMNANT
CLOUD/SHEAR LINE ACROSS THE LEEWARD ISLANDS NEAR DOMINICA TO
14N71W. LOW LEVEL CONFLUENCE BETWEEN NE WINDS AND TRADEWINDS
ALONG THE SHEAR LINE ARE GENERATING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS WITHIN 55 NM ON EITHER SIDE OF THE SHEAR
AXIS. TRADE WINDS MOVING ACROSS THE SE CARIBBEAN ARE BANKING
SOME LOW LEVEL MOISTURE...PROVIDING FOCUS FOR SCATTERED SHOWERS
WITHIN 40 NM OFF THE COAST OF PANAMA AND COSTA RICA BETWEEN
80W-84W. THE UPPER LEVELS OF THE CARIBBEAN ARE DOMINATED BY A
BROAD UPPER LEVEL RIDGE GIVING THE CARIBBEAN A DRY SW FLOW
ALOFT...PROVIDING FAIR WEATHER CONDITIONS TO THE REMAINDER OF
THE BASIN.

ATLANTIC OCEAN...
A DISSIPATING BOUNDARY ENTERS THE DISCUSSION AREA AS A COLD
FRONT NEAR 32N28W...EXTENDING SW ALONG TO 23N40W...BECOMING
STATIONARY TO 16N60W. SCATTERED SHOWERS ARE WITHIN 40 NM ON
EITHER SIDE OF THE DISSIPATING COLD FRONT N OF 23N...WHILE
ISOLATED SHOWERS ARE WITHIN 20 NM EITHER SIDE OF THE DISSIPATING
STATIONARY FRONT. THIS SYSTEM HAS LOST ITS UPPER LEVEL SUPPORT
AND IT IS EXPECTED TO CONTINUE TO WEAKEN OVER THE NEXT 24 HOURS.
HOWEVER...A SECOND ROUND OF COLD AIR ADVECTION IS BEHIND THIS
BOUNDARY...ANALYZED AS A COLD FRONT EXTENDING ALONG 32N40W
27N48W 25N57W. THIS FRONT IS SUPPORTED ALOFT BY A RATHER FAST
MOVING SHORTWAVE EMBEDDED IN AN AREA OF DIFFLUENCE NOTED ON
WATER VAPOR IMAGERY FROM 30N TO 40N BETWEEN 34W AND 44W.
SCATTERED SHOWERS ARE WITHIN 85 NM AHEAD OF THE FRONT N OF 27N.
SURFACE RIDGING IS ELSEWHERE ACROSS THE WESTERN AND EASTERN
REGIONS OF THE ATLC ANCHORED BY A 1025 MB HIGH NORTHEAST OF THE
BAHAMAS NEAR 29N76W AND A 1022 MB HIGH N OF THE CANARY ISLANDS
NEAR 31N17W.

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

$$

GARCIA




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