[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 202324
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE DEC 20 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
2315 UTC.

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

THE MONSOON TROUGH REMAINS INLAND OVER W AFRICA TO THE COAST OF
GUINEA NEAR 10N14W CONTINUING SW TO 7N18W. THE ITCZ CONTINUES
FROM 7N18W ALONG 4N30W 3N40W TO 4N47W. SCATTERED WEAK TO
MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF THE ITCZ
AXIS.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT IS MOVING ACROSS THE NW BASIN THIS EVENING
EXTENDING SW FROM THE COAST OF WRN LOUISIANA NEAR 30N93W TO THE
COAST OF MEXICO AND INLAND NEAR 24N98W. RADAR IMAGERY INDICATES
A STRONG LINE OF SHOWERS/THUNDERSTORMS ALONG THE FRONT AXIS WITH
SCATTERED SHOWERS 50 NM AHEAD AND BEHIND THE AXIS N OF 25N. NLY
WINDS UP TO 25 KTS ARE ALSO BEHIND THE FRONT WITH MOSTLY SSE
WINDS OF 15-20 KTS ACROSS THE REMAINDER OF THE BASIN. RADAR AND
SATELLITE IMAGERY ARE ALSO INDICATING ANOTHER AREA OF SCATTERED
SHOWERS ACROSS THE ERN HALF OF THE BASIN BETWEEN 85W-89W. THE
FRONT IS EXPECTED TO SLOWLY MOVE EWD OVER THE NEXT 24 HOURS
BEFORE STALLING AND RETREATING BACK TO THE NW BEFORE A SECOND
FRONT MOVES OFF THE COAST ON THURSDAY.

CARIBBEAN SEA...
A DISSIPATING COLD FRONT IS LYING ACROSS THE FAR NE CARIBBEAN
ISLANDS ALONG 18N TO 70W PRODUCING SCATTERED SHOWERS WITHIN 50
NM EITHER SIDE THE AXIS. THE FRONT IS EXPECTED TO STALL AND
CONTINUE DISSIPATING OVER THE NEXT 24 HOURS. ENE TRADEWIND FLOW
15-20 KTS IS ELSEWHERE ACROSS MUCH OF THE CARIBBEAN. LITTLE
CLUSTERS OF SCATTERED SHOWERS ARE EMBEDDED WITHIN THE TRADEWIND
FLOW WITH MORE CONCENTRATED ACTIVITY OVER THE SW CARIBBEAN DUE
TO SURFACE CONVERGENCE NEAR THE WEAKER MONSOON TROUGH EXTENDING
ACROSS PANAMA TO NRN COLOMBIA. THE MONSOON TROUGH HAS DIMINISHED
COMPARED TO THE PAST FEW DAYS...BUT AMPLE MOISTURE REMAINS
PRESENT. EXPECT STRONG TRADEWIND FLOW TO REMAIN ACROSS MUCH OF
THE BASIN AS HIGH PRESSURE OVER THE WRN ATLC CONTINUES TO CREATE
A STRONG PRESSURE GRADIENT. A SURFACE TROUGH AND ASSOCIATED
CONVECTION IS ALSO E OF THE WINDWARD ISLANDS AND IS EXPECTED TO
ADVECT WWD WHICH WILL IMPACT THE SRN WINDWARD ISLANDS.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL TROUGH CONTINUES TO SLOWLY PUSH EASTWARD
SUPPORTING A COLD FRONT ANALYZED INTO THE DISCUSSION AREA ALONG
NEAR 32N40W EXTENDING SW ALONG 22N50W TO THE NE CARIBBEAN AS A
DISSIPATING COLD FRONT ALONG 18N. ISOLATED SHOWERS ARE ONLY
WITHIN 50 NM EITHER SIDE OF THE AXIS. A 1027 MB HIGH IS BEHIND
THE FRONT COVERING THE REMAINDER OF THE WRN ATLC CENTERED NEAR
30N70W. FARTHER S IN THE TROPICAL ATLC...A SLOW MOVING SURFACE
TROUGH IS ABOUT 230 NM E OF THE MOST SRN LESSER ANTILLES...
ANALYZED FROM 13N53W TO 10N59W. SCATTERED SHOWERS ARE WITHIN 200
NM ON EITHER SIDE OF THE AXIS. THESE SHOWERS MAY DRIFT WWD AND
IMPACT THE SRN WINDWARD ISLANDS. THE REMAINDER OF THE ERN ATLC
IS EXPERIENCING MOSTLY FAIR WEATHER DUE TO SURFACE RIDGING
AROUND A 1034 MB HIGH NEAR 41N20W AND ANOTHER 1033 MB HIGH NEAR
38N13W. EXPECT THE FRONTAL SYSTEM IN THE CENTRAL ATLC TO MOVE NE
OVER THE NEXT SEVERAL DAYS.

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

$$

GARCIA



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