[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 272342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE DEC 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N11W TO
05N19W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
05N19W TO 04N35W TO 02N50W. SCATTERED MODERATE CONVECTION IS
FROM 02N-06N BETWEEN 20W-41W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL TROUGH IS LOCATED
OVER THE GREAT LAKES REGION WITH AXIS EXTENDING SOUTHWARD TO THE
SOUTHERN MISSISSIPPI RIVER VALLEY AND INTO THE GULF TO A BASE
NEAR 26N92W. THIS TROUGH SUPPORTS A COLD FRONT ANALYZED FROM NE
FLORIDA NEAR JACKSONVILLE TO TAMPA BAY AND INTO THE SE GULF
ALONG 28N83W TO 23N88W TO 20N93W. ISOLATED SHOWERS ARE OCCURRING
WITHIN 75 NM EITHER SIDE OF THE FRONT AND POSSIBLE ISOLATED
SHOWERS OCCURRING OVER THE SW GULF S OF 23N W OF 92W. THE
REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF MOSTLY WESTERLY
ZONAL FLOW ALOFT AND A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH
CENTERED OVER THE RIO GRANDE RIVER VALLEY NEAR 29N101W. WITH THE
COLD FRONT EXPECTED TO PUSH EAST OF THE BASIN BY EARLY WEDNESDAY
AND HIGH PRESSURE TO SLIDE EASTWARD FROM TEXAS TO THE SE
CONUS...NORTHERLY WINDS WILL PERSIST AND CONDITIONS ARE EXPECTED
TO REMAIN FAIR THROUGH LATE WEDNESDAY INTO EARLY THURSDAY.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE EXTENDS ACROSS THE CARIBBEAN SEA WITH AXIS
FROM NORTHERN VENEZUELA NEAR 10N67W NW TO NEAR 18N83W. WATER
VAPOR IMAGERY INDICATES VERY DRY AIR AND SUBSIDENCE OVER MUCH OF
THE BASIN THIS EVENING WHICH IS RESULTING IN RATHER TRANQUIL
CONDITIONS AT THE SURFACE. HOWEVER...FRESH TO STRONG E-NE TRADES
CONTINUE GENERALLY BETWEEN 70W-80W AND THIS OVERALL PATTERN IS
FORECAST TO PERSIST THROUGH EARLY FRIDAY AS A RIDGE WILL
POSITION ITSELF IN THE SW NORTH ATLC AND INCREASE THE TRADES DUE
TO AN INCREASED PRESSURE GRADIENT. THE TRADES WILL REMAIN STRONG
BASIN-WIDE THROUGH THE UPCOMING WEEKEND.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY THIS
EVENING ACROSS THE GREAT LAKES REGION AND THIS TROUGH SUPPORTS A
COLD FRONT ANALYZED AT 27/2100 UTC FROM 34N79W TO THE FLORIDA
COAST NEAR 29N81W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING
WITHIN 150 NM EAST OF THE FRONT. THE REMAINDER OF THE SW NORTH
ATLC IS UNDER THE INFLUENCE OF A 1023 MB SURFACE HIGH CENTERED
JUST EAST OF BERMUDA NEAR 33N66W. FARTHER EAST...AN UPPER LEVEL
LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NORTH OF THE
DISCUSSION AREA NEAR 37N51W AND AN ASSOCIATED TROUGH AXIS ALONG
52W. THE COLD FRONT IS ANALYZED FROM 32N48W TO 28N50W TO 24N60W
TO 24N65W THEN AS A DISSIPATING COLD FRONT ON THE SOUTHERN
PERIPHERY OF THE AFOREMENTIONED SURFACE RIDGE TO 26N72W. WITH
MOISTURE REMAINING LIMITED WITH THIS FRONT...ONLY POSSIBLE
ISOLATED SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE BOUNDARY.
THE MAIN IMPACT WITH THIS FRONT IS GALE FORCE NW WINDS TO 35 KT
NORTH OF 29N W OF THE COLD FRONT TO 55W. THESE CONDITIONS S OF
31N OVER THE FORECAST WATERS ARE ANTICIPATED TO DIMINISH BELOW
WARNING CRITERIA THROUGH THE OVERNIGHT HOURS. THE REMAINDER OF
THE EASTERN ATLC ALOFT IS DOMINATED BY AN UPPER LEVEL LOW
CENTERED NEAR 21N29W. MIDDLE TO UPPER LEVEL MOISTURE CONTINUES
TO BE DRAWN N-NE ON THE SOUTHEASTERN PERIPHERY OF THE UPPER
LEVEL LOW WITH ISOLATED SHOWERS OCCURRING FROM NORTH OF THE ITCZ
AXIS ALONG 05N TO 24N E OF 28W. WIDELY SCATTERED SHOWERS ARE
OCCURRING CLOSER TO THE UPPER LEVEL LOW CENTER FROM 19N-26N
BETWEEN 26W-33W. AT THE SURFACE N OF 20N...A SURFACE RIDGE AXIS
EXTENDS FROM 36N20W TO 23N42W.

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

$$
HUFFMAN



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