[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 172345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 17 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 2330 UTC.

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

THE MONSOON TROUGH REMAINS INLAND ACROSS AFRICA. THE ITCZ
EXTENDS WESTWARD FROM THE COAST OF SIERRA LEONE NEAR 7N13W ALONG
6N20W 7N30W 6N40W TO 6N46W. SCATTERED MODERATE TO STRONG
CONVECTION IS WITHIN 130 NM ON EITHER SIDE OF THE AXIS BETWEEN
30W-46W.

...DISCUSSION...

GULF OF MEXICO...
A FRONTAL BOUNDARY CONTINUES TO SLOWLY SHIFT SE ACROSS THE NRN
GULF EXTENDING FROM NRN FLORIDA AS A COLD FRONT NEAR 28N82W
CONTINUING WSW ALONG 26N87W TO 26N92W...BECOMING STATIONARY AND
TURNING SWD ALONG 26N95W AND MOVING INLAND INTO MEXICO S OF
TAMPICO NEAR 21N97W. OVERCAST SKIES WITH LOW VISIBILITIES AND
ISOLATED SHOWERS ARE WITHIN 110 NM N AND W OF THE FRONTAL
BOUNDARY ALONG WITH NORTHERLY WINDS GUSTING TO 20 KTS. THE FRONT
LACKS ANY STRONG UPPER LEVEL SUPPORT DUE TO DRY WESTERLY FLOW
ALOFT COVERING MUCH OF THE BASIN THIS EVENING. MOSTLY FAIR
CONDITIONS ARE ELSEWHERE ACROSS THE GULF WITH A FEW PATCHES OF
CLOUDS AND POSSIBLE ISOLATED SHOWERS. DUE TO THE LACK OF UPPER
LEVEL SUPPORT...THE FRONT IS EXPECTED TO STALL AND DISSIPATE
OVER THE NEXT DAY OR SO AS HIGH PRESSURE BUILDS OVER THE REGION.

CARIBBEAN SEA...
SCATTERED SHOWERS AND THUNDERSTORMS ARE OVER THE SW CARIBBEAN
DUE TO MONSOONAL FLOW AROUND THE AXIS ANALYZED ACROSS WRN PANAMA
INTO NRN COLOMBIA. A 1010 MB LOW IS EMBEDDED IN THE MONSOONAL
GYRE NEAR 10N80W. THE ACTIVITY IS AFFECTING MOSTLY THE COASTAL
WATERS OF PANAMA...COSTA RICA...AND NICARAGUA WITHIN 130 NM. AN
UPPER LEVEL ANTICYCLONE IS NOTICED IN THE THE UPPER LEVEL CLOUD
FIELD W OF 72W...PROVIDING DIFFLUENCE ALOFT OVER THE SW
CARIBBEAN HELPING PRODUCE THE CONVECTION AROUND THE MONSOON
TROF. ACROSS THE S-ERN CARIBBEAN...A SHEAR LINE EXTENDS ACROSS
THE FAR SE CARIBBEAN ALONG 11N62W T0 12N71W DEPICTING A
WEAKENING DELINEATION BETWEEN NE AND ELY WINDS0 KTS. ISOLATED
SHOWERS ARE WITHIN 70 NM N OF THE AXIS. OTHERWISE...FAIR WEATHER
CONDITIONS ARE ELSEWHERE ACROSS THE DISCUSSION AREA THIS
EVENING. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS WITH
MOISTURE REMAINING OVER THE SW CARIBBEAN AND GENTLE TO MODERATE
NE WINDS OVER THE CENTRAL AND ERN CARIBBEAN.

ATLANTIC OCEAN...
WEAK UPPER LEVEL RIDGING CONTINUES TO COVER THE WRN ATLC
SUPPORTING A 1021 MB HIGH NEAR 27N67W...PROVIDING MOSTLY FAIR
WEATHER ASIDE A FEW AREAS OF STRATOCUMULUS CLOUDS THAT MAY
SOURCE A FEW ISOLATED SHOWERS W OF 58W. AN UPPER LEVEL LOW IS TO
THE E NEAR 27N50W REFLECTING A SURFACE 1009 MB LOW. TWO FRONTAL
BOUNDARIES ACCOMPANY THE LOW. THE MAIN FRONT IS NOW BECOMING
STATIONARY WITH AN OCCLUDED PORTION ALONG 27N52W TO 29N46W THEN
TURNING STATIONARY ALONG 23N45W TO 17N48W. A WEAK SURFACE TROUGH
CONTINUES FARTHER TO THE SW TO 12N51W. A SECONDARY COLD FRONT
EXTENDS FROM THE LOW CENTER ALONG 24N48W TO 21N51W. THE
STRONGEST ACTIVITY IS E OF THE MAIN FRONT N OF 17N WITHIN 70-140
NM. SCATTERED SHOWERS AND THUNDERSTORMS ARE ALSO NEAR THE LOW
CENTER FROM 24N-28N BETWEEN 47W-50W. THE REMAINDER OF THE ERN
ATLC IS EXPERIENCING MOSTLY FAIR WEATHER DUE TO SURFACE RIDGING
AROUND A 1034 MB HIGH S OF THE AZORES NEAR 35N25W. EXPECT THE
LOW PRESSURE SYSTEM IN THE CENTRAL ATLC TO REMAIN SOMEWHAT
STATIONARY WITH CONVECTION OVER THE NEXT DAY OR SO.

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

$$

GARCIA




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