[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 042353
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN DEC 04 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 2300 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ONLY A SMALL PORTION OVER WATER FROM
THE COAST OF GUINEA NEAR 10N14W TO 8N17W. THE ITCZ CONTINUES
FROM 8N17W ALONG 3N30W 4N43W 3N51W. ISOLATED MODERATE/STRONG
CONVECTION IS WITHIN 250 NM N...100 NM S OF THE AXIS BETWEEN
26W-49W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE RIDGING CONTINUES TO DOMINATE THE GULF OF MEXICO WITH
AXIS FROM THE BIG BEND OF FLORIDA TO THE BAY OF CAMPECHE. THIS
PATTERN IS PROVIDING MAINLY 15-20 KT NE-E SURFACE FLOW ACROSS
THE BASIN AROUND THE RIDGE WITH LIGHTER WINDS ON THE WRN
PERIPHERY. PATCHES OF ISOLATED SHOWERS ARE EMBEDDED WITHIN THE
ANTI-CYCLONIC FLOW MAINLY N OF 24N. ALOFT...MOSTLY DRY AIR
COVERS THE AREA AROUND AN UPPER LEVEL RIDGE WITH AXIS EXTENDING
FROM THE BAY OF CAMPECHE TO CENTRAL FLORIDA AND INTO THE W ATLC.
A SWATH OF UPPER LEVEL MOISTURE LIES ON THE WRN SIDE OF THE
UPPER RIDGE BETWEEN THE RIDGE AND AN APPROACHING TROUGH OVER THE
WRN CONUS. THIS MOISTURE IS SUPPORTING A FEW UPPER LEVEL CLOUDS
OVER THE NW GULF ALONG WITH ISOLATED SHOWERS AT THE SURFACE DUE
TO AN APPROACHING COLD FRONT. THE AFOREMENTIONED UPPER TROUGH
OVER THE WRN CONUS SHOULD BEGIN TO PUSH EWD SUPPORTING THE
FRONTAL BOUNDARY NEAR THE TEXAS COASTLINE. THE FRONT IS EXPECTED
TO MOVE OVER THE NW GULF WATERS WITHIN 24 HOURS. NLY WINDS UP TO
25 KTS ARE EXPECTED BEHIND THE FRONT.

CARIBBEAN SEA...
MAINLY NELY FLOW COVERS THE WRN HALF OF THE CARIBBEAN AROUND THE
SURFACE RIDGE THAT COVERS THE FAR ERN CONUS...GULF OF
MEXICO...AND WRN ATLC. POSSIBLE ISOLATED SHOWERS ARE EMBEDDED
WITHIN THIS FLOW AND MORE CONCENTRATED NEAR THE CENTRAL AMERICAN
COASTLINE AND INLAND. ALOFT...DRY AIR AND SUBSIDENCE COVER THE
AREA W OF 70W AROUND AN UPPER LEVEL TROUGH WITH AXIS FROM
HISPANIOLA TO COLUMBIA. E OF 70W...DIFFLUENCE AROUND THE ERN
SIDE OF THE UPPER TROUGH IS HELPING SUPPORT SCATTERED
SHOWERS/THUNDERSTORMS E OF A LINE FROM THE VIRGIN ISLANDS TO THE
NW CORNER OF VENEZUELA. SOME OF THIS ACTIVITY IS ENHANCED BY A
SURFACE TROUGH EXTENDING FROM THE CENTRAL ATLC INTO THE NE
CARIBBEAN ALONG 19N63W TO 16N64W. THIS AREA INCLUDING MUCH OF
THE LEEWARD AND WINDWARD ISLANDS HAVE ALREADY RECEIVED LARGE
AMOUNTS OF RAIN OVER THE PAST SEVERAL DAYS. WITH MOISTURE
EXPECTED TO REMAIN OVER THIS AREA...THERE IS THE POTENTIAL FOR
FLOODING ESPECIALLY IN AREAS OF HIGH TERRAIN.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE IS MOVING OVER THE FAR WRN ATLC WITH AXIS
JUST E OF THE ERN UNITED STATES SEABOARD SUPPORTING SURFACE
RIDGING AROUND A 1037 MB HIGH S OF NOVA SCOTIA NEAR 42N64W. DRY
AIR ALOFT ACCOMPANIES THE UPPER RIDGE PROVIDING MOSTLY FAIR
WEATHER. AN UPPER LEVEL TROUGH TO THE E ALONG 32N61W TO
HISPANIOLA NEAR 19N69W IS SUPPORTING A FRONTAL BOUNDARY N OF THE
DISCUSSION AREA...TRANSITIONING INTO A SURFACE TROUGH ALONG
31N60W 23N63W 19N63W. SURFACE CONVERGENCE ALONG WITH UPPER LEVEL
DIFFLUENCE IS HELPING SUPPORT SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS MAINLY E OF THE SURFACE TROUGH WITHIN 300 NM. AN
UPPER LEVEL RIDGE IS E OF THE SURFACE TROUGH SANDWICHED BETWEEN
THE AFOREMENTIONED UPPER TROUGH AND AN UPPER LEVEL LOW NEAR
30N33W. THE UPPER LOW IS SUPPORTING A SECOND SURFACE TROUGH FROM
32N47W TO 27N43W. SCATTERED SHOWERS ARE FARTHER E OF THE TROUGH
FROM 24N-30N BETWEEN 31W-40W. TO THE S...ANOTHER SURFACE TROUGH
IS ALONG 17N46W TO 11N48W. ISOLATED SHOWERS ARE WITHIN 300 NM
EITHER SIDE OF THE AXIS. EXPECT THE SURFACE TROUGH IN THE
CENTRAL ATLC TO REMAIN THE MAIN ACTIVE WEATHER MAKER AS IT
REMAINS MOSTLY STATIONARY FOR THE NEXT 24 HOURS.

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

$$
WALTON





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