[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 152338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU DEC 15 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.

...THE ITCZ/THE MONSOON TROUGH...

THE ITCZ EXTENDS ACROSS FAR WRN AFRICA TO THE COAST OF LIBERIA
NEAR 6N11W CONTINUING ALONG 6N20W 4N30W 4N39W. ISOLATED MODERATE
CONVECTION IS WITHIN 250 NM N OF THE AXIS BETWEEN 20W-39W.

...DISCUSSION...

THE GULF OF MEXICO...
MOSTLY FAIR WEATHER IS ACROSS THE GULF OF MEXICO THIS EVENING
DUE TO SURFACE RIDGING AROUND A PAIR OF 1026 MB HIGHS OFF THE SE
UNITED STATES COAST WITH AXIS EXTENDING FROM NE FLORIDA TO THE
BAY OF CAMPECHE. MAINLY SE FLOW OF 10-15 KTS IS AROUND THE RIDGE
WITH A FEW AREAS OF LOW-LEVEL CLOUDS AND POSSIBLE ISOLATED
SHOWERS ESPECIALLY IN THE SE AND NW CORNERS OF THE BASIN.
ALOFT...AN UPPER LEVEL RIDGE COVERS THE AREA WITH AXIS EXTENDING
JUST E OF THE FLORIDA PENINSULA ALONG 79W. MOSTLY DRY AIR
ACCOMPANIES THE UPPER RIDGE WHICH IS HELPING MAINTAIN THE FAIR
SURFACE CONDITIONS. SURFACE RIDGING IS EXPECTED TO REMAIN OVER
THE ERN HALF OF THE BASIN WITH A COLD FRONT APPROACHING THE NW
CORNER EXPECTED TO MOVE OVER THE GULF WATERS OVERNIGHT WITH
STRONGER NLY WINDS UP TO 20 KTS BEHIND IT.

THE CARIBBEAN SEA...
MUCH OF THE NW CARIBBEAN IS EXPERIENCING MOSTLY FAIR WEATHER DUE
TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE EXTENDING FROM NW
VENEZUELA TO WRN CUBA. THIS PATTERN IS ALSO PROVIDING DIFFLUENCE
ALOFT OVER THE SW CARIBBEAN BETWEEN THE UPPER RIDGE AND A
HORIZONTALLY ALIGNED UPPER TROUGH OVER THE ERN PACIFIC.
DIFFLUENCE ALOFT COMBINED WITH SURFACE CONVERGENCE NEAR THE
MONSOON TROUGH EXTENDING ACROSS COSTA RICA TO NRN COLOMBIA IS
HELPING PRODUCE SCATTERED SHOWERS/THUNDERSTORMS S OF 13N BETWEEN
73W-85W. A DISSIPATING COLD FRONT IS MOVING ACROSS THE ERN
CARIBBEAN FROM 17N63W TO 15N77W SUPPORTING ISOLATED SHOWERS
WITHIN 75 NM EITHER SIDE OF THE AXIS ALONG WITH SLIGHTLY
STRONGER NELY WINDS UP TO 25 KTS TO THE N OF THE AXIS. A SURFACE
TROUGH IS TO THE S ALONG 13N61W TO 12N69W WITH ISOLATED SHOWERS
WITHIN 50 NM TO THE S OF THE AXIS. EXPECT THE FRONT TO DISSIPATE
WITHIN THE NEXT 24 HOURS WITH WINDS UP TO 25 KTS REMAINING OVER
THE CENTRAL CARIBBEAN.

THE ATLANTIC OCEAN...
UPPER LEVEL RIDGING COVERS THE FAR WRN ATLC SUPPORTING A PAIR OF
1026 MB SURFACE HIGHS NEAR 32N81W AND 33N73W WHICH ARE PROVIDING
MOSTLY FAIR WEATHER ACROSS THE WRN ATLC. A NARROW UPPER LEVEL
TROUGH IS ALONG 54W SUPPORTING A COLD FRONT ALONG 32N48W 21N56W
17N6W. GALE FORCE WINDS ARE NOTED TO THE E OF THE FRONT TO 44W N
OF 28N. MOST OF THE SHOWER ACTIVITY IS ALSO TO THE E UNDER THE
AREA OF DIFFLUENCE ALOFT. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE N OF 12N BETWEEN 44W-52W. A SURFACE TROUGH IS
S OF THE FRONTAL BOUNDARY ALONG 23N52W 16N53W 13N61W. POSSIBLE
ISOLATED SHOWERS ARE ALONG THE AXIS. FARTHER E...UPPER LEVEL
RIDGING COVERS THE MAJORITY OF THE E ATLC CENTERED NEAR 35N21W
SUPPORTING A 1033 MB HIGH NEAR 36N11W WHICH IS PROVIDING FAIR
WEATHER ACROSS MUCH OF THE AREA E OF 43W. AN UPPER LEVEL LOW IS
SOUTH OF THE UPPER RIDGE CENTERED NEAR 23N26W. AN UPPER LEVEL
JET TO THE S OF THE UPPER LOW CENTER IS SUPPORTING SOME UPPER
LEVEL CLOUDS TO THE N OF THE ITCZ REGION. EXPECT THE COLD FRONT
IN THE CENTRAL ATLC TO CONTINUE TO MOVE TO THE E OVER THE NEXT
COUPLE OF DAYS.

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

$$
WALTON






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