000
AXNT20 KNHC 201122
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1115 UTC.

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

THE MONSOON TROUGH EXTENDS FROM THE COAST OF SIERRA LEONE NEAR 
8N13W TO 7N17W. THE ITCZ CONTINUES FROM 7N17W TO 5N30W TO 
3N51W. SCATTERED MODERATE CONVECTION IS FROM 3N-5N BETWEEN 
23W-27W. ISOLATED MODERATE CONVECTION IS FROM 3N-6N BETWEEN 
36W-47W.  

...DISCUSSION...

GULF OF MEXICO...
A 1026 MB HIGH IS CENTERED OVER THE W ATLANTIC NEAR 31N74W. 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. RADAR IMAGERY 
SHOWS SCATTERED SHOWERS S OF THE FLORIDA PANHANDLE FROM 29N-31N 
BETWEEN 86W-89W...AND ALONG THE COAST OF TEXAS N OF 26N BETWEEN 
95W-97W. A COLD FRONT IS JUST INLAND OVER S TEXAS. THERE IS AN 
IMMEDIATE 15 DEGREE DROP IN TEMPERATURES ACROSS THE FRONT. 
SCATTERED MODERATE CONVECTION IS WELL E OF THE FRONT ALONG THE 
BOARDER OF LOUISIANA N OF 30N BETWEEN 93W-95W. EXPECT THE COLD 
FRONT IN 24 HOURS TO EXTEND FROM SE LOUISIANA TO TAMPICO MEXICO 
WITH RAIN AND SHOWERS...AND PLENTY OF COLD AIR ADVECTION BEHIND 
THE FRONT. EXPECT SOUTHERLY RETURN FLOW OVER THE REMAINDER OF 
THE GULF. ALSO EXPECT SCATTERED MODERATE CONVECTION OVER THE E 
GULF E OF 88W DUE TO THE RETURN FLOW.  
  
CARIBBEAN SEA...
THE TAIL END OF A DISSIPATING COLD FRONT EXTENDS FROM N OF THE 
LEEWARD ISLANDS AT 20N60W TO N HISPANIOLA AT 19N73W. 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. A MONSOON TROUGH EXTENDS FROM N COLOMBIA TO COSTA 
RICA. ISOLATED 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...AND HONDURAS. SIMILAR SHOWERS ARE OVER 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 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 1026 MB HIGH IS CENTERED OVER THE W ATLANTIC NEAR 31N74W 
PRODUCING FAIR WEATHER. A COLD FRONT IS OVER THE CENTRAL AND 
WESTERN ATLANTIC FROM 30N47W TO N OF THE LEEWARD ISLANDS ALONG 
25N50W 20N60W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THE FRONT. 
A SURFACE TROUGH IS E OF THE LESSER ANTILLES FROM 15N52W 
TO 9N56W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THE TROUGH. A 
1032 MB HIGH IS CENTERED NEAR THE AZORES AT 39N22W. A RIDGE AXIS 
EXTENDS S FROM THE HIGH TO 22N40W. EXPECT THE COLD FRONT TO MOVE 
E TO THE EASTERN ATLANTIC OVER THE NEXT 24 HOURS TO 30N38W WITH 
CONVECTION.   

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

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FORMOSA