[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 130553
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST TUE DEC 13 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N12W TO
05N16W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
05N16W TO 05N30W TO 05N43W. NO SIGNIFICANT CONVECTION IS NOTED
ON SATELLITE IMAGERY.

...DISCUSSION...

GULF OF MEXICO...
WEST-NORTHWESTERLY UPPER LEVEL FLOW IS NOTED ON WATER VAPOR
IMAGERY ON THE EASTERN PERIPHERY OF AN UPPER LEVEL RIDGE ACROSS
THE SOUTH-CENTRAL CONUS WITH AXIS ALONG 95W. MOSTLY DRY AIR AND
OVERALL SUBSIDENCE IS NOTED WITH THIS UPPER LEVEL FEATURE ACROSS
THE GULF WHILE IT SUPPORTS A SURFACE RIDGE EXTENDING FROM THE
MID-ATLC STATES SOUTHWESTWARD FROM THE FLORIDA PANHANDLE NEAR
30N85W TO THE SW GULF NEAR 20N97W. WITH E TO SE FLOW NOTED OVER
PORTIONS OF THE WESTERN GULF...A FEW ISOLATED SHOWERS ARE
POSSIBLE W OF 90W THROUGH THE OVERNIGHT HOURS. OTHERWISE...THE
SURFACE RIDGE IS EXPECTED TO REMAIN MOSTLY STATIONARY THROUGH
WEDNESDAY...SHIFT EAST INTO THE SW NORTH ATLC THURSDAY...AND
ALLOW A WEAK COLD FRONT TO EMERGE OFF THE TEXAS AND LOUISIANA
GULF COAST BY LATE THURSDAY.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE CONTINUES TO INFLUENCE MUCH OF THE
CARIBBEAN THIS EVENING WITH AXIS EXTENDING FROM OVER VENEZUELA
NEAR 07N66W TO OVER EASTERN CUBA NEAR 20N76W. THIS ALONG WITH A
RELATIVELY WEAK PRESSURE GRADIENT ACROSS THE BASIN IS PROVIDING
FOR OVERALL BENIGN CONDITIONS EVERYWHERE EXCLUDING THE SW GULF.
ON THE WESTERN PERIPHERY OF THE UPPER LEVEL RIDGE...SOUTHERLY
DIFFLUENT FLOW ALOFT CONTINUES TO SUSTAIN SCATTERED SHOWERS AND
TSTMS S OF 15N BETWEEN 71W-85W...INCLUDING PORTIONS OF NORTHERN
COLOMBIA...PANAMA...COSTA RICA...AND NICARAGUA. MOST OF THIS
CONVECTIVE ACTIVITY IS FOCUSED ALONG THE MONSOON TROUGH AXIS
WHICH EXTENDS FROM THE E PACIFIC INTO THE SW CARIBBEAN ALONG
11N. LOOKING AHEAD...NE TRADES ARE EXPECTED TO REMAIN STRONGEST
OVER THE NW CARIBBEAN THROUGH THURSDAY AND THEN SPREAD EASTWARD
AS STRONGER SURFACE HIGH PRESSURE BUILDS IN ACROSS THE SW NORTH
ATLC WATERS.

ATLANTIC OCEAN...
UPPER LEVEL WESTERLY FLOW IS NOTED OVER THE SW NORTH ATLC
BETWEEN AN UPPER LEVEL RIDGE TO THE SOUTH OVER THE CARIBBEAN SEA
AND WEAK UPPER LEVEL TROUGHING LOCATED N OF 32N OVER THE NW
NORTH ATLC WATERS. MOSTLY DRY AIR AND STABLE CONDITIONS ARE
NOTED ON SATELLITE IMAGERY W OF 65W AS A 1033 MB HIGH REMAINS
ANCHORED OVER THE MID-ATLC STATES NEAR 38N78W. NE WINDS IN THE
RANGE OF 20 TO 25 KT RESULT AS A PRODUCT OF AN INCREASED
PRESSURE GRADIENT BETWEEN THIS HIGH AND SURFACE TROUGHING N OF
20N BETWEEN 60W-70W. THE ANALYZED SURFACE TROUGH IS LOCATED FROM
20N63W TO 32N65W WITH LOW-LEVEL CONVERGENCE EAST OF THE AXIS
GENERATING A BROAD AREA OF ISOLATED SHOWERS FROM 13N-24N BETWEEN
48W-62W...AND FROM 24N-32N BETWEEN 55W-62W. THE REMAINDER OF THE
CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE
RIDGE ANCHORED BY A 1032 MB HIGH CENTERED NEAR 34N35W.

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

$$
HUFFMAN




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