[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 131151
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...ITCZ/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N13W TO
04N19W TO 05N30W TO 02N51W. ISOLATED MODERATE CONVECTION IS
WITHIN 30 NM EITHER SIDE OF A LINE FROM 07N46W TO 06N55W.

...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 EXTENDING FROM THE SW GULF
NEAR 20N97W TO BEYOND THE MID-MISSISSIPPI RIVER VALLEY REGION.
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 WESTERN GULF NEAR 22N98W.
WITH E TO SE FLOW NOTED OVER PORTIONS OF THE WESTERN GULF...A
FEW ISOLATED SHOWERS ARE POSSIBLE W OF 90W THROUGH THE MORNING
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 FRONTAL BOUNDARY 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 MORNING WITH AN 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 CARIBBEAN. ON THE WESTERN PERIPHERY OF THE UPPER LEVEL
RIDGE...SOUTHERLY DIFFLUENT FLOW ALOFT CONTINUES TO SUSTAIN
SCATTERED SHOWERS AND ISOLATED TSTMS S OF 15N BETWEEN 71W-86W...
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 10N. 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 38N79W. 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
22N62W TO 32N65W WITH LOW-LEVEL CONVERGENCE MAXIMIZED EAST OF
THE AXIS GENERATING A BROAD AREA OF ISOLATED SHOWERS FROM
14N-23N BETWEEN 40W-61W...AND FROM 23N-32N BETWEEN 55W-62W. THE
REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE
OF A SURFACE RIDGE ANCHORED BY A 1030 MB HIGH CENTERED NEAR
34N34W.

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

$$
HUFFMAN




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