000 AXNT20 KNHC 291746 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU APR 29 2010 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 1745 UTC... ...THE ITCZ... THE ITCZ IS CENTERED FROM FROM THE NORTHERN LIBERIA COAST NEAR 6N11W WESTWARD ALONG 5N20W 4N30W 3N40W INTO THE NORTHEASTERN COAST OF BRAZIL NEAR 1.5N50W. SCATTERED MODERATE TO STRONG CONVECTION IS IN THE COASTAL WATERS OF AFRICA NEAR COTE D'VOIRE...LIBERIA...AND SIERRA LEONE. MODERATE TO STRONG CONVECTION IS WITHIN 100 NM EITHER SIDE OF THE AXIS BETWEEN 16W AND 25W. ELSEWHERE WEST OF 33W...MODERATE TO STRONG CONVECTION IS WITHIN 160 NM ON EITHER SIDE OF THE AXIS. ...DISCUSSION... GULF OF MEXICO... MARINE OBSERVATIONS ACROSS THE BASIN SHOW A MODERATE SOUTHEASTERLY COMPONENT ACROSS THE BASIN. AN UPPER LEVEL RIDGE OF HIGH PRESSURE IS BUILDING OVER THE REGION...SUPPRESSING ANY DEEP CONVECTION NORTH OF 25N. HOWEVER...A BROAD UPPER LEVEL LONGWAVE IS MOVING ACROSS THE GULF...NOTED BY STRONG SUBSIDENCE OF DRY AIR NORTH OF 24N WEST OF 90W...MOVING SOUTHEASTWARD. MOIST UNSTABLE AIR FROM CENTRAL AMERICA IS MOVING OVER THE SOUTHEAST CORNER OF THE BASIN. THIS SHARP CONTRAST BETWEEN DRY SUBSIDENT AIR AND MOIST UNSTABLE AIR IS LEADING TO AN AREA OF WEAK TO MODERATE CONVECTION EAST OF 90W SOUTH OF 24N. DOPPLER RADAR IMAGERY INDICATES SHOWERS IN THIS REGION MOVING INTO SOUTHERN FLORIDA AND THE FLORIDA STRAIGHTS. OVER THE NEXT 24 HOURS...COMPUTER MODELS CONTINUE TO BRING SHOWERY WEATHER OVER THE SOUTHEAST CORNER OF THE BASIN INCLUDING THE SOUTHERN FLORIDA PENINSULA. THE CARIBBEAN SEA... ABUNDANT MID TO UPPER LEVEL MOISTURE FROM CENTRAL AMERICA AND EASTERN TROPICAL PACIFIC CONTINUES TO MOVE OVER THE FAR NORTHWEST BASIN...FUELING A LINGERING SURFACE TROUGH THAT CROSSES CENTRAL CUBA AND CONTINUES WEST-SOUTHWESTWARD INTO FAR WESTERN BASIN...ENTERING CENTRAL AMERICA THROUGH BELIZE TO CENTRAL GUATEMALA. MODERATE TO STRONG CONVECTION IS WITHIN 120 NM ON EITHER SIDE OF THE BOUNDARY WEST OF 84W...AND WITHIN 60 NM EITHER SIDE OF THE BOUNDARY EAST OF 84W. THIS FRONTAL BOUNDARY IS EXPECTED TO START WEAKENING OVER THE NEXT 24 HOURS. ONLY A FEW SHOWERS MAY REMAIN OVER THE AREA...ESPECIALLY OVER CUBA. PART OF THE ITCZ IS OVER NORTHERN COLOMBIA...PANAMA...COSTA RICA...AND SOUTHERN NICARAGUA...AFFECTING THE WATERS NEAR THE COAST OF THESE COUNTRIES. COMPUTER MODELS CONTINUE TO SHOW CONVECTION IN THIS REGION THE REST OF THE WORK WEEK. ELSEWHERE ACROSS THE CARIBBEAN SEA EAST OF 75W...FAIR WEATHER IS OBSERVED ACROSS THIS REGION WITH A SURFACE PRESSURE GRADIENT COMPARATIVELY WEAK...AND LIGHT TO MODERATE TRADE WINDS. ATLANTIC OCEAN... AN UPPER LEVEL RIDGE OF HIGH PRESSURE IS SLOWLY ENTERING THE FAR WESTERN ATLANTIC. THE SURFACE HIGH PRESSURE SYSTEM IS NEAR 29N75W. THEREFORE...FAIR WEATHER IS OBSERVED NORTH OF 24N WEST OF 60W. A COLD FRONT ENTERS THE CENTRAL ATLANTIC AREA OF DISCUSSION EXTENDING WEST-SOUTHWEST ALONG 32N50W 25N60W 22N70W BECOMING A SURFACE TROUGH THAT CROSSES THE SOUTHERN BAHAMAS AND CONTINUES OVER CENTRAL CUBA. MODERATE CONVECTION IS WITHIN 90 NM ON EITHER SIDE OF THE COLD FRONT AND 60 NM ON EITHER SIDE OF THE SURFACE TROUGH. THIS FRONTAL SYSTEM IS SUPPORTED BY A BRAD UPPER LEVEL SHORTWAVE TROUGH THAT PASSES THROUGH THE WESTERN ATLANTIC. AN UPPER LEVEL RIDGE OF HIGH PRESSURE COVERS MOST OF THE EASTERN BASIN SUPPRESSING DEEP CONVECTION EAST OF 45W. THE STRONGEST AREA OF SURFACE HIGH PRESSURE IS NEAR 36N30W. COMPUTER MODELS INDICATE THE COLD FRONT WILL SLOWLY DETACH FROM THE SURFACE TROUGH AND CONTINUE TO MOVE EASTWARD WITH CONVECTION AHEAD OF IT. THE SURFACE TROUGH WILL REMAIN NEAR THE SAME AREA AND WEAKEN WITH LESS ACTIVITY EMBEDDED IN IT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA