000 AXNT20 KNHC 282339 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED APR 28 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC... ...THE ITCZ... THE ITCZ IS CENTERED FROM N LIBERIA NEAR 7N12W ALONG 5N20W 4N30W 3N40W AND INTO NE BRAZIL NEAR EQ50W. ISOLATED MODERATE/STRONG CONVECTION IS WITHIN 100 NM N OF THE AXIS 22W-39W. SIMILAR ACTIVITY IS ALSO FROM 4N-6N BETWEEN 41W-47W. ...DISCUSSION... THE GULF OF MEXICO... SURFACE RIDGING CONTINUES TO BUILD ACROSS THE GULF OF MEXICO ANCHORED BY A 1019 MB HIGH S OF PANAMA CITY FLORIDA...AND A 1018 MB HIGH OVER W MISSISSIPPI KEEPING MUCH OF THE GULF COAST UNDER FAIR CONDITIONS. WATER VAPOR IMAGERY INDICATES MID TO UPPER LEVEL MOISTURE IS BEING DRAWN FROM THE E PACIFIC ACROSS THE YUCATAN AND INTO THE GULF OF MEXICO AROUND AN UPPER LEVEL RIDGE CENTERED N OF VENEZUELA SUPPORTING HIGH CLOUDS ACROSS MUCH OF THE AREA. TOTAL PRECIPITABLE WATER IMAGERY ALSO INDICATES ENHANCED MOISTURE ACROSS THE SW GULF WHERE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS RANGE FROM 20W-24W E OF 94W. EXPECT THE SURFACE RIDGE TO GRADUALLY SHIFT EWD ALLOWING SLY RETURN FLOW TO INCREASE ACROSS THE W GULF. MOISTURE ACROSS THE SW GULF SHOULD REMAIN IN PLACE SUPPORTING ISOLATED SHOWERS ACROSS THAT PORTION OF THE BASIN. THE CARIBBEAN SEA... A DISSIPATING STATIONARY FRONT CONTINUES TO LINE THE NW CARIBBEAN FROM ERN CUBA NEAR 21N77W TO THE YUCATAN PENINSULA AT 20N87W. SCATTERED SHOWERS ARE WITHIN 75 NM N OF THE AXIS. A CLUSTER OF THUNDERSTORMS ARE ALSO S OF THE FRONT ACROSS E CUBA. THE FRONT IS SUPPORTED BY AN UPPER LEVEL LONGWAVE TROUGH ACROSS THE W ATLC. HOWEVER...AN UPPER LEVEL RIDGE COVERS THE CARIBBEAN CENTERED N OF VENEZUELA. WATER VAPOR IMAGERY INDICATES UPPER LEVEL DRY AIR ACROSS THE MAJORITY OF THE BASIN E OF THE FRONT SUPPORTING GENERALLY FAIR WEATHER OVER THE REMAINDER OF THE AREA. SCATTERED SHOWERS/THUNDERSTORMS REMAIN OVER MUCH OF CENTRAL AMERICA...AND NRN COLOMBIA DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC ITCZ WHICH CROSSES SRN COSTA RICA AND LINES THE PANAMA COAST. EXPECT THE FRONT TO CONTINUE TO DISSIPATE WHILE MOISTURE REMAINS ACROSS CENTRAL AMERICA AND THE NW CARIBBEAN. THE ATLANTIC OCEAN... A DEEP LAYER TROUGH CONTINUES TO IMPACT THE WRN ATLC THIS EVENING WITH A DISSIPATING COLD FRONT EXTENDING FROM 31N61W ALONG 26N67W TO 23N71W WHERE IT BECOMES STATIONARY TO ERN CUBA NEAR 21N77W AND INTO THE NW CARIBBEAN. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 250 NM E OF THE FRONT N OF 25N...AND WITHIN 75 NM EITHER SIDE OF THE AXIS S OF 25N. A REINFORCING COLD FRONT IS W OF THE DISSIPATING FRONT ENTERING THE DISCUSSION NEAR 32N65W ALONG 27N70W 24N76W. THIS IS A FAST MOVING FRONT THAT WILL EVENTUALLY TAKE OVER THE DISSIPATING FRONT AND MERGE INTO ONE BOUNDARY. AN UPPER LEVEL LONGWAVE TROUGH COVERS THE W ATLC SUPPORTING THE FRONTAL SYSTEM. UPPER LEVEL DIFFLUENCE TO THE E OF THE UPPER TROUGH IS ALSO ENHANCING SHOWER/THUNDERSTORM ACTIVITY ALONG THE DISSIPATING SURFACE BOUNDARY. FARTHER E...A SURFACE RIDGE DOMINATES ANCHORED BY A 1030 MB HIGH NEAR 34N34W PROVIDING GENERALLY FAIR WEATHER ACROSS MUCH OF THE REMAINDER OF THE BASIN. HOWEVER...A SURFACE TROUGH...REMNANTS OF A FRONTAL BOUNDARY...PROTRUDES INTO THE RIDGE ALONG 29N22W 23N32W 20N44W. POSSIBLE ISOLATED SHOWERS ARE WITHIN 75 NM EITHER SIDE OF THE TROUGH. ALOFT...AN UPPER LEVEL RIDGE EXTENDS FROM THE CARIBBEAN TO THE NE ACROSS THE AZORES ISLANDS SUPPORTING THE SURFACE RIDGE ACROSS THE CENTRAL/E ATLC. A NARROW UPPER LEVEL TROUGH EXTENDS FROM THE CANARY ISLANDS TO THE NE BRAZIL COAST SUPPORTING THE SURFACE TROUGH. THIS UPPER LEVEL TROUGH IS MOST LIKELY ENHANCING CONVECTION ALONG THE ERN PORTION OF THE ATLC ITCZ. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON