000
AXNT20 KNHC 200519
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0515 UTC.

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

THE MONSOON TROUGH REMAINS INLAND OVER W AFRICA TO THE COAST OF 
SIERRA LEONE NEAR 8N13W CONTINUING SW TO 7N16W. THE ITCZ 
CONTINUES FROM 7N16W TO 4N30W TO 3N51W. ISOLATED MODERATE 
CONVECTION IS FROM 3N-6N BETWEEN 22W-27W.  

...DISCUSSION...

GULF OF MEXICO...
A 1027 MB HIGH IS CENTERED OFF THE COAST OF SOUTH CAROLINA NEAR 
31N75W. A RIDGE AXIS EXTENDS W FROM THE HIGH TO THE NW GULF OF 
MEXICO NEAR 30N94W. 15-20 KT SE RETURN FLOW IS OVER THE GULF 
WITH MOSTLY FAIR WEATHER. RADAR IMAGERY SHOWS HOWEVER 
SCATTERED SHOWERS S OF THE FLORIDA PANHANDLE FROM 29N-31N 
BETWEEN 87W-88W. A COLD FRONT IS INLAND OVER E TEXAS. SCATTERED 
RAIN AND SHOWERS ARE E OF THE FRONT N OF 28N BETWEEN 93W-97W. 
THERE IS AN IMMEDIATE 20 DEGREE DROP IN TEMPERATURES ACROSS THE 
FRONT. EXPECT THE COLD FRONT IN 24 HOURS TO EXTEND FROM SW 
LOUISIANA TO S OF MATAMOROS MEXICO WITH RAIN AND SHOWERS AND 
PLENTY COLD AIR ADVECTION BEHIND THE FRONT. EXPECT SOUTHERLY 
RETURN FLOW AND FAIR WEATHER OVER THE REMAINDER OF THE GULF. 
  
CARIBBEAN SEA...
THE TAIL END OF A COLD FRONT N HISPANIOLA AT 20N70W TO CENTRAL 
CUBA AT 22N79W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THE FRONT. 
15-30 KT TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH STRONGEST 
WIND ALONG THE COAST OF N COLOMBIA. WIDELY SCATTERED MODERATE 
CONVECTION IS OVER N COLOMBIA...PANAMA...AND COSTA RICA MOSTLY 
DUE TO THE MONSOON TROUGH. BROKEN TO OVERCAST LOW CLOUDS WITH 
ISOLATED SHOWERS ARE FURTHER N OVER NICARAGUA...HONDURAS...EL 
SALVADOR...AND BELIZE. SIMILAR SHOWERS ARE OVER W CUBA. MORE 
SHOWERS ARE OVER THE WINDWARD ISLANDS AND THE COAST OF N 
VENEZUELA S OF 13N E OF 68W. EXPECT OVER THE NEXT 24 HOURS FOR 
THE COLD FRONT TO WEAKEN AND DRIFT E TO PUERTO RICO AND THE 
VIRGIN ISLANDS WITH SHOWERS. ALSO EXPECT MORE SHOWERS TO ADVECT 
FROM THE ATLANTIC TO THE WINDWARD ISLANDS AND N VENEZUELA. 
LASTLY EXPECT CONTINUED CONVECTION OVER THE SW CARIBBEAN DUE TO 
THE MONSOON TROUGH.   

ATLANTIC OCEAN...
A 1027 MB HIGH IS OFF THE COAST OF SOUTH CAROLINA NEAR 31N75W 
PRODUCING FAIR WEATHER. A COLD FRONT IS OVER THE CENTRAL AND 
WESTERN ATLANTIC FROM 30N49W TO N OF HISPANIOLA ALONG 21N60W 
20N70W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THE FRONT. A 
PREFRONTAL TROUGH IS OVER THE CENTRAL ATLANTIC FROM 30N45W TO 
24N47W. SCATTERED SHOWERS ARE WITHIN 15 NM OF THE TROUGH. 
ANOTHER SURFACE TROUGH IS E OF THE LESSER ANTILLES FROM 14N53W 
TO 9N60W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THE TROUGH. A 
1033 MB HIGH IS CENTERED OVER THE AZORES NEAR 39N24W. A RIDGE 
AXIS EXTENDS S FROM THE HIGH TO 24N37W. EXPECT THE COLD FRONT TO 
MOVE E TO THE EASTERN ATLANTIC OVER THE NEXT 24 HOURS TO 30N40W 
WITH CONVECTION.   

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

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FORMOSA