[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 011126
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST THU DEC 01 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 MONSOON TROUGH EXTENDS ACROSS AFRICA ENTERING THE E TROPICAL
ATLC NEAR 11N15W TO 9N18W. THE ITCZ NEAR 9N18W EXTENDING ALONG
6N26W 9N37W TO SOUTH AMERICA NEAR 6N57W. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 4N-10N E OF 30W TO
JUST INLAND OVER SW AFRICA NEAR 11W AND WITHIN 90 NM S O F THE
ITCZ BETWEEN 36W-42W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH IS DIGGING S OVER THE E GULF TO 25N MAINLY E OF
88W WITH ZONAL WESTERLY FLOW ALOFT PREVAILING ACROSS THE
REMAINDER OF THE AREA. DRY STABLE AIR AND STRONG SUBSIDENCE
CONTINUES TO DOMINATE THE AREA WITH SCATTERED COLD AIR
STRATOCUMULUS CLOUDS OVER THE FAR E GULF E OF 85W. MOSTLY CLEAR
SKIES ARE OVER THE REMAINDER OF THE GULF. A SURFACE RIDGE COVERS
THE GULF ANCHORED BY A 1026 MB HIGH OVER S OHIO. SURFACE RIDGE
WILL PERSIST THROUGH SAT. A COLD FRONT WILL MOVE INTO THE NW
GULF LATE SUN WITH GALE CONDITIONS EXPECTED IN SW GULF W OF THE
FRONT LATE MON.

CARIBBEAN SEA...
THE STATIONARY FRONT HAS WEAKEN INTO A SHEAR LINE EXTENDING FROM
CUBA NEAR CABO CRUZ OVER W OF JAMAICA TO 11N81W. ISOLATED
SHOWERS ARE POSSIBLE OVER THE NW CARIBBEAN W OF THE SHEAR LINE.
AN UPPER RIDGE DOMINATES THE NW CARIBBEAN W OF 70W WHILE A
NARROW UPPER TROUGH FROM THE W/CENTRAL ATLC EXTENDS S ACROSS THE
VIRGIN ISLANDS TO THE ABC ISLANDS. DRY STABLE AIR ALOFT AND
STRONG SUBSIDENCE COVERS ALL BUT THE FAR SE CARIBBEAN. THE
MONSOON TROUGH EXTENDS ACROSS THE SW CARIBBEAN FROM COLOMBIA
NEAR 11N75W TO ACROSS COSTA RICA INTO THE E PACIFIC REGION NEAR
10N84W AND IS POSSIBLY GENERATING ISOLATED SHOWERS WITHIN 75 NM
ALONG THE COAST OF COLOMBIA AND S OF 13N W OF 81W. A SURFACE
TROUGH IS E OF LESSER ANTILLES BUT CONTINUES TO GENERATE
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS E OF A LINE FROM THE
ISLAND OF SAINT LUCIA TO THE COAST OF VENEZUELA NEAR 11N64W TO
OVER THE WINDWARD ISLANDS. THIS IS LEAVING THE CENTRAL CARIBBEAN
WITH FAIR WEATHER AGAIN THIS MORNING. SHEAR LINE WILL DISSIPATE
LATE TONIGHT. SURFACE TROUGH LINGER E OF THE LESSER ANTILLES
THROUGH MON.

ATLANTIC OCEAN...
AN UPPER TROUGH IS MOVING INTO THE W ATLC N OF 25N W OF 75W WITH
RE-INFORCING SHOT OF COLD AIR OVER THE SE CONUS AND E GULF OF
MEXICO. A COLD FRONT REMAINS ACROSS THE W ATLC SUPPORTED BY AN
UPPER TROUGH WELL N OF THE DISCUSSION AREA ENTERING THE REGION
NEAR 32N67W 24N73W WHERE IT BECOMES STATIONARY CONTINUING ACROSS
THE S BAHAMA ISLANDS TO CUBA NEAR SAINT LUCIA. ISOLATED SHOWERS
ARE WITHIN 60 NM W OF THE COLD FRONT. A NARROWING UPPER TROUGH
IS IN THE W/CENTRAL ATLC EXTENDING AN AXIS THROUGH 32N66W SE
ALONG 24N57W THEN SW ACROSS THE VIRGIN ISLANDS INTO THE
CARIBBEAN SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM A 1006
MB SURFACE LOW NEAR 29N60W S TO 20N63W. A SECOND SURFACE TROUGH
IS IN THE W TROPICAL ATLC EXTENDING FROM 20N58W OVER BARBADOS TO
E TRINIDAD WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN
120/150 NM E OF THE SURFACE TROUGH S OF 14N. DRY STABLE AIR IS W
OF THE UPPER TROUGH WITH MOSTLY CLEAR SKIES W TO THE W ATLC
FRONT. A NARROW HIGH AMPLITUDE UPPER RIDGE TO THE E OF THE UPPER
TROUGH IS BEGINNING TO WEAKEN AND NOW EXTENDS AN AXIS FROM THE W
TROPICAL ATLC NEAR 14N44W TO BEYOND 32N56W PROVIDING DIFFLUENCE
ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS WITHIN 90/120 NM OF LINE FROM THE TROPICS NEAR
5N46W 13N54W TO 20N56W. DENSE CLOUD COVER WITH POSSIBLE ISOLATED
SHOWERS ARE WITHIN 150/200 NM OF LINE FROM 18N52W 27N54W TO
BEYOND 32N59W. AN UPPER TROUGH COVERS THE E ATLC N OF 20N E OF
40W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N23W
TO 27N34W. SCATTERED SHOWERS ARE WITHIN 45 NM SE OF THE FRONT.
THE REMAINDER OF THE E ATLC IS DOMINATED BY A SURFACE RIDGE
ANCHORED BY A 1034 MB HIGH ABOUT 550 NM W-NW OF THE AZORES.
WEAKENING COLD FRONT WILL DISSIPATE TONIGHT AS THE SURFACE
TROUGH TO THE E WILL MOVE N EARLY FRI AS THE LOW DISSIPATES. A
SURFACE RIDGE WILL BUILD BEHIND THE FRONT THROUGH MON.

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

$$
PAW






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