000
AXNT20 KNHC 041731
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON MAY 04 2009

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

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

...THE ITCZ...

THE ITCZ AXIS IS ALONG 6N8W 4N15W CROSSING THE EQUATOR NEAR 32W 
AND CONTINUING ALONG 2S36W INTO NE BRAZIL NEAR 3S46W. THE ITCZ 
IS VERY ACTIVE TODAY ACROSS THE BASIN E OF 40W. SCATTERED/ 
NUMEROUS STRONG CONVECTION IS WITHIN A 45 NM RADIUS OF 3.5N1.5W 
AND WITHIN A 60 NM RADIUS OF 3.5N16.5W. SCATTERED MODERATE/ 
STRONG CONVECTION IS WITHIN 120 NM OF LINE FROM 5N11W 2N26W WITH 
CLUSTERS OF SIMILAR CONVECTION FROM THE SW COAST OF AFRICA TO 
JUST S OF THE EQUATOR E OF 10W ACROSS THE PRIME MERIDIAN. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF 2N ACROSS 
THE EQUATOR BETWEEN 11W-15W AND FROM 4N TO S OF THE EQUATOR 
BETWEEN 27W-37W. 

...DISCUSSION...

GULF OF MEXICO...
BROAD DEEP LAYERED TROUGH COVERS THE E U.S. AND THE GULF OF 
MEXICO WITH THE ASSOCIATED COLD FRONT ENTERING THE GULF OF 
MEXICO OVER CENTRAL LOUISIANA NEAR VERMILION BAY SW INTO TEXAS 
JUST S OF CORPUS CHRISTI. LITTLE IN THE WAY OF SHOWERS ARE W OF 
THE FRONT...BUT HEAVY SHOWERS/STRONG THUNDERSTORMS ARE INLAND 
AND ALONG THE IMMEDIATE GULF COAST FROM PENSACOLA FLORIDA TO THE 
E SIDE OF VERMILION BAY LOUISIANA. A SURFACE RIDGE EXTENDS 
ACROSS THE FLORIDA PENINSULA FROM THE W ATLC OVER THE E GULF. 
THIS IS PRODUCING S TO SE WINDS OVER THE GULF EXPECT WITH 
NORTHERLY WINDS NW OF THE FRONT. THE FRONT IS EXPECTED TO STALL 
OVER THE NW GULF WATERS DURING THE NEXT 24 HOURS BEFORE 
WEAKENING SLIGHTLY AND LIFTING NORTHWARD AS A STATIONARY/WARM 
BOUNDARY. BROKEN/OVERCAST LOW LEVEL CLOUDS ARE NW OF THE FRONT 
WITH HIGH CIRRUS DEBRIS CLOUDS OVER THE NE GULF KEEPING THE 
REMAINDER OF THE GULF UNDER CLEAR SKIES THIS AFTERNOON. 

CARIBBEAN SEA...
BROAD UPPER RIDGE DOMINATES THE CARIBBEAN ANCHORED OVER 
VENEZUELA ADVECTING TROPICAL MOISTURE OVER THE AREA E OF 80W. A 
SURFACE TROUGH EXTENDS OVER THE E CARIBBEAN FROM THE VIRGIN 
ISLANDS S ALONG 65W TO JUST OFF THE NE COAST OF VENEZUELA 
PRODUCING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS 
OVER THE LESSER ANTILLES N OF 13N BETWEEN 58W-66W. THIS SURFACE 
TROUGH COUPLED WITH THE TROPICAL MOISTURE ARE GENERATING 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 14N BETWEEN 
64W-73W INCLUDING THE ABC ISLANDS. LIGHT TO MODERATE TRADE WINDS 
COVER THE CARIBBEAN MOSTLY DUE TO THE RELAXED PRESSURE GRADIENT 
LEAVING THE REMAINDER OF THE CARIBBEAN WITH SOME ISOLATED LOW 
LEVEL SHOWERS DOTTING THE AREA. 

ATLANTIC OCEAN...
THE ATLANTIC BASIN IS DOMINATED BY A SURFACE HIGH PRESSURE RIDGE 
ANCHORED WELL NORTH OF THE DISCUSSION AREA AND EXTENDING SW 
ACROSS BERMUDA AND THE FLORIDA PENINSULA TO OVER THE E GULF OF 
MEXICO. AN UPPER LOW IN THE W ATLC IS CENTERED NEAR 27N70W 
PROVIDING SUPPORT FOR A SURFACE TROUGH THAT EXTENDS FROM 29N70W 
TO 22N68W AND PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS 
WITHIN 120 NM OF A LINE FROM 24N62W 27N67W TO 27N71W. TROPICAL 
MOISTURE FROM THE CARIBBEAN IS BEING DRAWN N INTO THE UPPER LOW 
GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS 
S OF 24N FROM 60W-66W TO OVER THE LEEWARD/VIRGIN ISLANDS AND 
PUERTO RICO. A SECOND UPPER LOW IS IN THE E ATLC NEAR 29N39W 
PROVIDING SUPPORT FOR A SURFACE TROUGH THAT EXTENDS FROM 24N38W 
TO BEYOND 32N42W GENERATING SIMILAR ACTIVITY FROM 29N TO BEYOND 
32N BETWEEN 35W-41W. AN AREA OF AFRICAN DUST IS OVER THE E 
TROPICAL ATLC FROM 7N-23N E OF 40W. 

$$
WALLACE