[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111143
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST TUE DEC 11 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO
08N19W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
08N19W TO 03N30W TO 04N47W TO 04N51W. ISOLATED MODERATE
CONVECTION IS FROM 04N-07N BETWEEN 10W-18W. SCATTERED MODERATE
CONVECTION IS FROM 07N-13N BETWEEN 36W-48W.

...DISCUSSION...

GULF OF MEXICO...
BROAD MIDDLE TO UPPER LEVEL TROUGHING IS OVER MUCH OF THE CONUS
WHICH IS PROVIDING THE GULF WITH SOUTHWESTERLY FLOW ALOFT. THE
TROUGHING SUPPORTS A COLD FRONT ANALYZED INTO THE GULF REGION
ACROSS THE FLORIDA PANHANDLE ALONG 30N85W TO 26N90W TO THE
MEXICO COAST NEAR 20N97W. ISOLATED SHOWERS ARE OCCURRING WITHIN
60 NM EITHER SIDE OF THE FRONT E OF 90W...AND ACROSS MUCH OF THE
WESTERN GULF NORTH OF THE FRONT W OF 90W. ANOTHER IMPACT WITH
THE FRONT IS 20 TO 25 KT NORTHERLY WINDS FOLLOW IN WAKE OF THE
FRONT S OF 26N. OTHERWISE...THE REMAINDER OF THE GULF IS UNDER
THE INFLUENCE OF WEAK PRE-FRONTAL TROUGHING WITH ISOLATED
SHOWERS AND TSTMS OCCURRING PRIMARILY EAST OF A SURFACE TROUGH
ANALYZED FROM 28N85W TO 23N88W TO 19N92W FROM 24N-28N E OF
86W...INCLUDING PORTIONS OF THE CENTRAL AND SOUTHERN FLORIDA
PENINSULA. THE COLD FRONT IS EXPECTED TO CONTINUE MOVING
EASTWARD INTO THE SW NORTH ATLC AND NW CARIBBEAN BY THURSDAY AS
HIGH PRESSURE BUILDS IN ACROSS THE GULF WITH PERSISTENT N-NE
WINDS.

CARIBBEAN SEA...
MUCH OF THE BASIN THIS MORNING IS UNDER TRANQUIL CONDITIONS AS
WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL RIDGE WITH AXIS
ALONG 73W IS PROVIDING A RELATIVELY DRY AND STABLE ATMOSPHERE. A
FEW ISOLATED SHOWERS AND TSTMS ARE HOWEVER OCCURRING OVER
PORTIONS OF THE SW CARIBBEAN S OF 11N DUE TO CLOSE PROXIMITY OF
THE MONSOON TROUGH AXIS WHICH EXTENDS FROM THE EASTERN PACIFIC
REGION ALONG 08N TO NORTHERN COLOMBIA NEAR 08N77W. OTHERWISE...A
FEW PASSING LOW-TOPPED ISOLATED SHOWERS ARE NOTED ON SATELLITE
IMAGERY ACROSS SW HISPANIOLA...THE ADJACENT WATERS SURROUNDING
THE WINDWARD PASSAGE...PUERTO RICO AND THE US/UK VIRGIN
ISLANDS...AND THE SE CARIBBEAN S OF 15N E OF 65W. WHILE
CONDITIONS ARE CONVECTIVELY QUIET...THE EXISTING PRESSURE
GRADIENT BETWEEN A STRONG CENTRAL ATLC RIDGE AND LOWER PRESSURE
ACROSS NORTHERN SOUTH AMERICA IS PROVIDING FOR ENHANCED EASTERLY
TRADE WIND FLOW IN THE RANGE OF 20 TO 30 KT. THESE TRADES ARE
EXPECTED TO PERSIST THROUGH LATE THURSDAY.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL RIDGE IS OVER THE SW NORTH ATLC WITH
AXIS EXTENDING NORTHWARD ALONG 73W FROM THE WESTERN CARIBBEAN
SEA. WATER VAPOR IMAGERY INDICATES FAIRLY DRY AIR REMAINS S OF
26N...HOWEVER WITH THE APPROACH OF A FRONTAL TROUGH CURRENTLY
OVER THE SE CONUS AND EASTERN GULF OF MEXICO...SCATTERED SHOWERS
AND TSTMS ARE OCCURRING ACROSS PORTIONS OF THE FLORIDA
PENINSULA...AND SW NORTH ATLC WATERS NW OF A LINE FROM 26N79W TO
32N74W. OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC AND
CENTRAL ATLC ARE UNDER THE INFLUENCE OF A 1027 MB HIGH CENTERED
NEAR 32N55W. A SURFACE RIDGE AXIS EXTENDS SW FROM THE HIGH TO
THE BAHAMAS AND CUBA. FARTHER EAST...AN UPPER LEVEL TROUGH IS
NOTED ON WATER VAPOR IMAGERY IN THE VICINITY OF 28N48W THAT
CONTINUES TO SUPPORT A STATIONARY FRONT ANALYZED FROM 32N23W TO
29N27W TO 25N28W THAT BECOMES A SHEAR LINE SW TO 10N60W.
ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM EITHER
SIDE OF THE STATIONARY FRONT. AS FOR THE SHEAR LINE...RECENT
SCATTEROMETER PASSES INDICATE THE PRESENCE OF THE AXIS WITH
STRONGER WINDS TO THE NORTH AND WIDELY SCATTERED SHOWERS AND
ISOLATED TSTMS OCCURRING WITHIN 240 NM EITHER SIDE OF THE SHEAR
LINE AXIS.

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

$$
HUFFMAN




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