000
AXNT20 KNHC 281733
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
205 PM EDT THU APR 28 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 1730 UTC.

...THE ITCZ...

FROM THE COAST OF SIERRA LEONE NEAR 7N12W...SW TO NEAR 3N20W TO 
NEAR THE EQUATOR AROUND 1N32W. THEN..IT RESUMES ALONG THE 
COASTAL WATERS OF BRAZIL NEAR 3S38W TO 2N50W. A BROAD AREA OF 
NUMEROUS MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS IS FROM 
5S-7N BETWEEN 10W-21W. SIMILAR CONVECTION IS OCCURRING WITHIN 80 
NM N OF THE ITCZ AXIS BETWEEN 20W-31W...AND WITHIN 100 NM ON 
EITHER SIDE OF THE AXIS BETWEEN 42W-51W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT IS MOVING EASTWARD ACROSS THE GULF AT ABOUT 15 KT. 
THIS BOUNDARY IS ANALYZED ENTERING THE FLORIDA COAST NEAR 30N84W 
EXTENDING SW ALONG 27N87W TO 25N92W WHERE IT BECOMES NEARLY 
STATIONARY INTO THE BAY OF CAMPECHE NEAR 20N95W. SATELLITE 
IMAGERY ALONG WITH DOPPLER DATA SHOWED SCATTERED SHOWERS AND 
ISOLATED THUNDERSTORMS ALONG THE BOUNDARY N OF 25N. GUSTY 
NORTHERLY WINDS UP TO 25 KT ARE OBSERVED BEHIND THE FRONT. 
CONSEQUENTLY...SOUTHERLY...RETURN FLOW UP TO 25 KT IS AHEAD OF 
THE FRONT. A SURFACE TROUGH PARALLELS THE WESTERN COAST OF THE 
YUCATAN PENINSULA. OTHER THAN CYCLONIC CURVATURE AROUND THE 
TROUGH...NO CONVECTION IS NOTED ON SATELLITE IMAGERY. LOOK FOR 
THE COLD FRONT TO CONTINUE TO TRACK EAST WITH CONVECTION OVER 
THE NEXT 24 HOURS. IN THE MEAN TIME...SURFACE RIDGING BUILDS 
BEHIND THE FRONT. 

CARIBBEAN SEA...
MOST OF THE CARIBBEAN SEA W OF 70W IS EXPERIENCING FAIR WEATHER 
CONDITIONS DUE TO DRY AND STABLE AIR ALOFT MOVING ACROSS THE 
AREA. AT SURFACE...SURFACE AND MARINE OBSERVATIONS INDICATE 
15-20 KT TRADE WINDS TURNING N WESTWARD W OF 77W N OF 14N. THE 
OVERALL FLOW CONTINUES TO ADVECT LOW LEVEL MOISTURE FROM THE 
TROPICAL ATLANTIC INTO THE EASTERN CARIBBEAN NOTED ON TOTAL 
PRECIPITABLE WATER IMAGERY. WITHIN THIS AREA OF LOW LEW LEVEL 
MOISTURE...A SURFACE TROUGH IS ANALYZED RIGHT OVER THE LESSER 
ANTILLES FROM MARTINIQUE TO TRINIDAD AND TOBAGO. THIS SYSTEM IS 
GENERATING SCATTERED SHOWERS AND THUNDERSTORMS TO THE ISLANDS S 
OF MARTINIQUE. HOWEVER...THE CONVECTION ASSOCIATED TO THIS AREA 
OF MOISTURE EXTENDS TO THE N CENTRAL BASIN...WITHIN 40 NM ON 
EITHER SIDE OF A LINE FROM 14N61W TO 17N71W. AS THIS AREA OF 
CONVECTION MOVES WEST...THIS GROUP OF ISLANDS WILL CONTINUE TO 
EXPERIENCE BAD WEATHER FOR AT LEAST THE NEXT 24 HOURS AS THE 
TROUGH MOVES WEST AT ABOUT 12 KT. ON A SECONDARY NOTE...SMOKE 
FROM THE FIRES IN CENTRAL AMERICA ARE AFFECTING VISIBILITIES 
DOWN TO LESS THAN 5 SM OVER THE FAR WEST CARIBBEAN SEA W OF 85W 
S OF 19N.

ATLANTIC OCEAN...
MOST OF THE DISCUSSION AREA IS DOMINATED BY A STRONG UPPER LEVEL 
RIDGE COVERING ALMOST THE ENTIRE ATLC BASIN. THIS UPPER RIDGE IS 
SUPPORTING A 1031 MB HIGH WOBBLING AROUND 34N56W. HOWEVER... 
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE ENTERING THE WEST 
ATLC AS AN UPPER LEVEL TROUGH MOVES OFF THE CONUS EASTERN 
SEABOARD SUPPORTING A COLD FRONT CURRENTLY OVER THE SE UNITED 
STATES AND GULF OF MEXICO. A WEAK 1009 MB LOW PRESSURE SYSTEM IS 
OVER THE FAR EAST ATLC NEAR 31N16W. A SURFACE TROUGH EXTENDS SSW 
FROM THE LOW CENTER TO NEAR 23N20W. NO SIGNIFICANT CONVECTION IS 
OBSERVED IN THE VICINITY OF THE LOW NOR THE SURFACE TROUGH. THIS 
SYSTEM WILL DISSIPATE OVER THE NEXT 12 TO 24 HOURS.

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

$$

GARCIA