000
AXNT20 KNHC 211719
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
205 PM EDT THU APR 21 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC. 

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N9W EQ21W 4S33W EQ50W. 
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 6N-1S BETWEEN 
6W-20W. ISOLATED MODERATE CONVECTION IS FROM EQ-4N BETWEEN 
20W-30W...AND FROM 4N-2S BETWEEN 40W-50W. WIDELY SCATTERED 
MODERATE CONVECTION IS FROM 2N-7S BETWEEN 30W-40W. 

...DISCUSSION...

THE GULF OF MEXICO...
10-20 KT SE RETURN FLOW DOMINATES FLORIDA AND THE GULF OF MEXICO 
WITH STRONGEST WINDS OVER THE W GULF W OF 90W...AND OVER THE 
STRAITS OF FLORIDA. FAIR WEATHER IS NOTED OVER THE ENTIRE GULF. 
IN THE UPPER LEVELS...NW FLOW PREVAILS. AN AREA OF UPPER 
LEVEL MOISTURE AND SCATTERED HIGH CLOUD ARE OVER THE COAST OF 
THE N GULF STATES. STRONG SUBSIDENCE IS OVER THE REMAINDER OF 
GULF. EXPECT...SOME AIR MASS SHOWERS AND THUNDERSTORMS OVER S 
MEXICO S OF 18N...IN THE AFTERNOON AND EVENING HOURS. 
OTHERWISE EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS.  

THE CARIBBEAN SEA...
10-20 KT TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH HIGHEST 
WINDS OVER THE WINDWARD PASSAGE. SCATTERED SHOWERS ARE OVER 
COSTA RICA...THE GULF OF HONDURAS...AND S OF HISPANIOLA. SIMILAR 
SHOWERS ARE OVER THE SE CARIBBEAN AND VENEZUELA S OF 12N BETWEEN 
60W-72W. MOSTLY FAIR WEATHER IS OVER THE REMAINDER OF THE 
CARIBBEAN. IN THE UPPER LEVELS...ZONAL FLOW DOMINATES THE AREA. 
UPPER LEVEL MOISTURE WITH BANDS OF SCATTERED HIGH CLOUDS ARE 
OVER THE CENTRAL CARIBBEAN FROM HONDURAS TO GUADELOUPE. STRONG 
SUBSIDENCE IS OVER THE REMAINDER OF THE SEA. EXPECT MORE SHOWERS 
OVER THE SE CARIBBEAN S OF 13N OVER THE NEXT 24 HOURS. ALSO 
EXPECT AIRMASS THUNDERSTORMS OVER W HONDURAS...EL SALVADOR...AND 
GUATEMALA OVER THE NEXT 24 HOURS.  

THE ATLANTIC OCEAN...
SURFACE RIDGING AND FAIR WEATHER DOMINATES THE W ATLANTIC W OF 
70W. A SURFACE TROUGH IS FURTHER E FROM 27N61W TO 21N65W. AN 
EMBEDDED 1009 MB LOW IS ON THE TROUGH AXIS AT 24N63W. ISOLATED 
MODERATE CONVECTION IS N OF THE LOW CENTER FROM 24N-28N BETWEEN 
56W-64W. A TIGHT SURFACE PRESSURE GRADIENT N OF THE LOW IS 
PRODUCING GALE FORCE WINDS WITHIN 180 NM OF THE NE QUADRANT. 
ELSEWHERE...A 1030 MB HIGH IS CENTERED OVER THE CENTRAL ATLANTIC 
NEAR 34N42W. IN THE UPPER LEVELS...AN UPPER LEVEL LOW IS OVER 
THE W ATLANTIC NEAR 29N67W SUPPORTING THE E ATLANTIC SURFACE 
SYSTEM. A 70 KT SUBTROPICAL JETSTREAM EXTENDS FROM OVER E CUBA 
AT 20N77W TO 23N60W TO 20N30W PRODUCING A LOT OF WESTERLY 
VERTICAL WINDSHEAR OVER THE SURFACE LOW. EXPECT OVER THE NEXT 24 
HOURS FOR...THE SURFACE LOW TO MOVE NW TO 26N63W WITH CONTINUED 
CONVECTION. WINDS ARE ALSO FORECAST DECREASE TO JUST BELOW GALE 
FORCE N OF THE CENTER IN ABOUT 6 HOURS.  

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

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FORMOSA