[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 110545
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SUN DEC 11 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0500 UTC.

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

THE MONSOON TROUGH EXTENDS ACROSS AFRICA TO THE COAST OF
GUINEA-BISSAU NEAR 11N15W CONTINUING SW TO 7N19W. THE ITCZ
CONTINUES FROM 7N19W ALONG 3N30W 2N43W. ISOLATED MODERATE/STRONG
CONVECTION IS WITHIN 250 NM N...120 NM S OF THE AXIS BETWEEN
19W-34W.

...DISCUSSION...

GULF OF MEXICO...
MAINLY NELY SURFACE FLOW COVERS THE GULF OF MEXICO TONIGHT
AROUND A 1035 MB HIGH CENTERED OVER SRN INDIANA. DUE TO THE
TIGHT PRESSURE GRADIENT...WINDY CONDITIONS PERSIST UP TO 25 KTS.
RADAR IMAGERY INDICATES SCATTERED SHOWERS ARE ACROSS THE NW GULF
LIKELY DUE TO WIND CONVERGENCE ALONG THE COASTLINE. ISOLATED
SHOWERS ARE ALSO ACROSS S FLORIDA AND POSSIBLE IN THE CENTRAL
GULF WHERE WIDESPREAD LOW-LEVEL CLOUDS ARE PRESENT.
ALOFT...MOIST WSWLY FLOW DOMINATES AROUND A BROAD UPPER LEVEL
TROUGH COVERING THE ERN CONUS. THE STRONG NELY SURFACE WINDS ARE
EXPECTED TO BEGIN DIMINISHING TO 15-20 KTS OVER THE NEXT 24-48
HOURS AS THE SURFACE RIDGE MOVES OFF TO THE E. ISOLATED SHOWERS
WILL ALSO LIKELY REMAIN ACROSS THE BASIN.

CARIBBEAN SEA...
DRY AIR ALOFT AROUND A BROAD UPPER RIDGE OVER THE CARIBBEAN IS
KEEPING MUCH OF THE BASIN UNDER CLEAR SKIES AND FAIR CONDITIONS.
HOWEVER...DUE TO A SHORTWAVE UPPER LEVEL TROUGH EXTENDING FROM
GUATEMALA INTO THE E PACIFIC...UPPER LEVEL DIFFLUENCE IS PRESENT
OVER THE AREA JUST E OF CENTRAL AMERICA. THIS ALONG WITH SMALL
AMOUNTS OF WIND SPEED CONVERGENCE IS HELPING PRODUCE SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF HONDURAS FROM 16N-19N
BETWEEN 84W-88W...AND E OF NICARAGUA...N OF COSTA RICA AND
PANAMA FROM 9N-16N BETWEEN 74W-83W. A SHEAR LINE REMAINS IN THE
NE CARIBBEAN ALONG 16N E OF 70W SUPPORTING ISOLATED SHOWERS FROM
16N-18N E OF 70W. 15-20 KT ENE WINDS ARE NOTED N OF THE AXIS
WHILE 5-10 KT WINDS ARE TO THE S. EXPECT SHOWERS/THUNDERSTORMS
TO REMAIN ACROSS THE FAR WRN CARIBBEAN AS WELL AS THE NE PORTION
OF THE BASIN AS A SURFACE TROUGH IN THE CENTRAL ATLC DRIFTS WWD.

ATLANTIC OCEAN...
A WEAK COLD FRONT IS IN THE W ATLC ENTERING THE DISCUSSION AREA
NEAR 32N75W TO JUST E OF CAPE CANAVERAL NEAR 28N81W. ISOLATED
SHOWERS ARE WITHIN 75 NM EITHER SIDE OF THE AXIS. THE FRONT IS
SUPPORTED BY AN UPPER LEVEL TROUGH OVER THE ERN CONUS. AN UPPER
LEVEL RIDGE IS TO THE E CENTERED NEAR 33N53W PROVIDING FAIR
WEATHER ACROSS THE REMAINDER OF THE W ATLC. ACROSS THE CENTRAL
ATLC...AN UPPER LEVEL LOW NEAR 22N54W SUPPORTS A SURFACE TROUGH
ALONG 27N58W 22N55W 16N60W CONTINUING AS A SHEAR LINE INTO THE
NE CARIBBEAN. GALE FORCE WINDS ARE NOTED E OF THE AXIS NEAR
25N51W AND EXPECTED TO CONTINUE THROUGH 1800 UTC. MOST OF THE
SHOWER ACTIVITY IS ALSO E OF THE AXIS WITH SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS FROM 15N-22N BETWEEN
42W-54W...AND FROM 22N-27N BETWEEN 47W-56W. SIMILAR ACTIVITY IS
ALSO WITHIN 150 NM N OF THE SHEAR AXIS. SURFACE RIDGING
DOMINATES THE ERN ATLC AROUND A 1034 MB HIGH NEAR 36N40W
SUPPORTED BY BROAD UPPER RIDGING COVERING THE NRN ATLC. AN UPPER
LEVEL TROUGH EXTENDS FROM THE CANARY ISLANDS TO E OF THE UPPER
LEVEL LOW IN THE CENTRAL ATLC. MAINLY WLY FLOW ALOFT COVERS THE
TROPICAL ATLC. EXPECT THE SURFACE TROUGH IN THE CENTRAL ATLC TO
DRIFT WWD OVER THE NEXT SEVERAL DAYS.

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

$$
WALTON





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