000
AXNT20 KNHC 221741
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
205 PM EDT FRI APR 22 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. 

...SPECIAL FEATURE...

AT 1500 UTC...A 1008 MB LOW IS CENTERED ABOUT 510 NM NNE OF 
PUERTO RICO AT 26.6N 63.6W WITH NEAR GALE FORCE WINDS N OF THE 
CENTER. A SECONDARY SURFACE SWIRL IS LOCATED 100 NM SW OF THE 
LOW CENTER NEAR 25.3N 64.7W INTERACTING WITH THE PRIMARY CENTER. 
A SURFACE TROUGH EXTENDS S FROM THE LOW CENTER TOWARDS PUERTO 
RICO ALONG 26N61W 23N61W 19N66W. WIDELY SCATTERED MODERATE 
CONVECTION IN BANDS IS N OF THE CENTER FROM 26N-30N BETWEEN 
60W-65W. A 1014 UTC WINDSAT PASS...AND A 1424 UTC ASCAT PASS 
CONFIRM 30 KT WINDS N OF THE CENTER. AN UPPER LEVEL LOW IS 
CENTERED DIRECTLY OVER THE SECONDARY SURFACE SWIRL. UPPER LEVEL 
DRY AIR IS WRAPPING AROUND THE WESTERN AND SOUTHERN PORTIONS OF 
THE SYSTEM. EXPECT THE SURFACE LOW CENTER TO TRACK SW TOWARDS 
HISPANIOLA AND WEAKEN OVER THE NEXT 24-48 HOURS WITH CONVECTION 
AND STRONGER WINDS N OF THE CENTER.    

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 7N11W EQ16W 4S30W EQ50W. 
ISOLATED MODERATE CONVECTION IS FROM EQ-2N BETWEEN 2W-8W... FROM 
3N-6N BETWEEN 8W-16W...AND FROM EQ-3N BETWEEN 20W-29W. FURTHER 
SOUTH...WIDELY SCATTERED MODERATE TO CONVECTION IS FROM 1S-10S 
BETWEEN 10W-30W. 

...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...ZONAL 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...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 THE E CARIBBEAN E OF 75W 
S OF HISPANIOLA. IN THE UPPER LEVELS...ZONAL FLOW DOMINATES 
THE AREA. UPPER LEVEL MOISTURE WITH BANDS OF SCATTERED HIGH 
CLOUDS ARE OVER THE CARIBBEAN S OF 18N. STRONG SUBSIDENCE IS 
OVER THE YUCATAN PENINSULA...NW CARIBBEAN...AND CUBA. 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...
A COLD FRONT IS OVER THE NW ATLANTIC FROM 32N68W TO 30N74W TO 
32N79W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THE FRONT. A 1008 
MB LOW IS CENTERED NEAR 26.6N 63.6W. SEE THE SPECIAL FEATURE 
SECTION ABOVE. ELSEWHERE...A 1029 MB HIGH IS CENTERED OVER THE 
CENTRAL ATLANTIC NEAR 34N37W. IN THE UPPER LEVELS...AN UPPER 
LEVEL LOW IS OVER THE W ATLANTIC NEAR 25N65W SUPPORTING THE E 
ATLANTIC SURFACE SYSTEM. A 70-90 KT SUBTROPICAL JETSTREAM 
EXTENDS FROM OVER E CUBA AT 20N77W TO 24N60W TO 20N30W PRODUCING 
A LOT OF WESTERLY VERTICAL WINDSHEAR OVER THE SURFACE LOW. 
EXPECT OVER THE NEXT 24 HOURS FOR...THE W ATLANTIC COLD FRONT TO 
MOVE SE OVER THE W ATLANTIC WITH SHOWERS...AND FOR THE SURFACE 
LOW CENTER TO TRACK SW TOWARDS HISPANIOLA AND WEAKEN WITH 
CONVECTION AND STRONGER WINDS N OF THE CENTER.    

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

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FORMOSA