[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 100533
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SAT DEC 10 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 REMAINS INLAND ACROSS AFRICA EXTENDING TO THE
COAST OF NRN GUINEA NEAR 11N15W. THE ITCZ CONTINUES FROM 11N15W
ALONG 7N26W 8N41W 7N49W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 3N-8N BETWEEN 23W-40W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE RIDGING CONTINUES TO COVER THE GULF OF MEXICO TONIGHT
AROUND A 1035 MB HIGH OVER ERN NEBRASKA. DESPITE THE HIGH
PRESSURE...LOW-LEVEL CLOUDS AND POSSIBLE ISOLATED SHOWERS ARE
EMBEDDED WITHIN THE ANTI-CYCLONIC FLOW ESPECIALLY OVER THE ERN
GULF AND FAR WRN GULF NEAR THE COAST OF MEXICO. FROM SATELLITE
IMAGERY...IT APPEARS THAT A SURFACE TROUGH MAY HAVE FORMED IN
THE SE GULF WHICH COULD BE CONTRIBUTING TO THE SHOWER ACTIVITY.
ALOFT...A BROAD UPPER LEVEL TROUGH IS MOVING ACROSS THE BASIN
WITH AXIS FROM LOUISIANA TO THE YUCATAN PENINSULA. WATER VAPOR
IMAGERY INDICATES DRY AIR SE OF A LINE FROM NE FLORIDA NEAR
30N81W TO THE BAY OF CAMPECHE NEAR 21N97W. TO THE NW OF THIS
LINE...UPPER LEVEL MOISTURE IS PRESENT SUPPORTING SOME UPPER
LEVEL CLOUDS ACROSS THE NRN GULF. AS THE HIGH PRESSURE SYSTEM
OVER THE CENTRAL CONUS SHIFTS EWD AND STRENGTHENS SLIGHTLY THE
PRESSURE GRADIENT OVER THE GULF WITH ALSO STRENGTHEN. THIS WILL
CAUSE AN INCREASE IN NE-E WINDS OF 20-25 KTS BASIN-WIDE OVER THE
NEXT 24 HOURS. ISOLATED SHOWERS WILL ALSO LIKELY REMAIN OVER THE
FAR WRN AND ERN PORTIONS OF THE GULF.

CARIBBEAN SEA...
DRY AIR ALOFT OVER THE NW CARIBBEAN IS MAINTAINING MOSTLY FAIR
WEATHER EXCEPT FOR AN AREA OF SCATTERED SHOWERS NEAR A SHEAR
AXIS EXTENDING FROM 21N82W TO 15N84W. THE AXIS DEPICTS THE
DELINEATION BETWEEN 20 KT NLY WINDS TO THE W AND 10 KT NELY
WINDS TO THE E. THIS IS CREATING CONVERGENCE ALONG THE AXIS AND
SUPPORTING SCATTERED SHOWERS WITHIN 100 NM W OF THE AXIS. AN
AREA OF SCATTERED SHOWERS IS ALSO FROM 10N-12N BETWEEN 77W-79W
WITH ISOLATED SHOWERS S OF 16N BETWEEN 75W-83W DUE TO BROAD
CYCLONIC FLOW AROUND THE MONSOON TROUGH AXIS EXTENDING ACROSS
CENTRAL COSTA RICA TO NRN COLOMBIA. SHOWERS/THUNDERSTORMS ARE
ALSO IMPACTING PUERTO RICO AND THE NRN-MOST LEEWARD ISLANDS DUE
TO AN ELONGATED UPPER LEVEL TROUGH TO THE NW OF THE ISLANDS.
MOST CONDITIONS ARE EXPECTED TO REMAIN OVER THIS PORTION OF THE
BASIN FOR AT LEAST THE NEXT 24 HOURS. THE REMAINDER OF THE BASIN
IS UNDER MOSTLY FAIR CONDITIONS WITH 15-20 KT NE-E TRADEWIND
FLOW.

ATLANTIC OCEAN...
A SURFACE TROUGH CONTINUES TO IMPACT THE WRN ATLC ALONG 31N73W
27N77W 23N77W. SCATTERED SHOWERS ARE WITHIN 75 NM NW OF THE
AXIS. ALOFT...AN UPPER LEVEL RIDGE DOMINATES THE WRN ATLC
CENTERED NEAR 30N62W PROVIDING MOSTLY FAIR WEATHER BESIDES THAT
NEAR THE SURFACE TROUGH...AND SCATTERED SHOWERS NEAR THE NRN
LEEWARD ISLANDS DUE TO A WEAK ELONGATED UPPER TROUGH ALONG
23N69W TO 17N62W. FARTHER E...AN UPPER LEVEL LOW IS IMPACTING
THE CENTRAL ATLC CENTERED NEAR 23N48W. IT IS SUPPORTING A
SURFACE TROUGH ALONG 28N49W 22N27W 17N51W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE MAINLY E OF THE AXIS WITHIN
300 NM...WITH SIMILAR ACTIVITY WITHIN 150 NM TO THE W FROM
22N-26N. MOISTURE NEAR THE UPPER LOW IS ALSO BEING DRAWN ACROSS
THE ERN ATLC TO NRN AFRICA IN WLY FLOW ALONG AROUND A NARROW
UPPER LEVEL TROUGH EXTENDING FROM THE UPPER LOW TO THE MADEIRA
ISLANDS AN ACROSS WRN SPAIN. TO THE S...AN UPPER LEVEL RIDGE
DOMINATES THE TROPICAL ATLC SUPPORTING A 1033 MB HIGH WHICH IS
COVERING THE REMAINDER OF THE ERN ATLC. EXPECT THE TROUGH IN THE
CENTRAL ATLC TO DRIFT WWD OVER THE NEXT COUPLE OF DAYS WHILE THE
TROUGH IN THE WRN ATLC GRADUALLY DISSIPATES.

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

$$
WALTON




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