000 AXNT20 KNHC 030534 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SUN APR 03 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED FROM THE SRN COAST OF LIBERIA NEAR 4N8W ALONG 2N20W 1N30W CROSSING THE EQUATOR NEAR 33W AND INTO NE BRAZIL TO NEAR 3S42W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 100 NM S OF THE AXIS BETWEEN 11W-14W...AND WITHIN 120 NM N OF THE AXIS BETWEEN 18W-31W. ...DISCUSSION... GULF OF MEXICO... THE GULF OF MEXICO REMAINS MOSTLY CLEAR UNDER THE INFLUENCE OF WEAK SURFACE RIDGING AROUND A 1018 MB HIGH CENTERED NEAR MOBILE ALABAMA. PATCHES OF LOW-LEVEL CLOUDS ARE ACROSS THE WRN HALF OF THE BASIN AS WELL JUST N OF WRN CUBA. SURFACE OBSERVATIONS FROM CUBA INDICATE THAT ISOLATED SHOWERS/THUNDERSTORMS ARE ASSOCIATED WITH SOME OF THESE CLOUDS. A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO IN THE FAR SW GULF FROM 19N-23N BETWEEN 96W-100W INDICATED BY LIGHTNING DATA. THESE STORMS ARE ASSOCIATED WITH A SHORTWAVE UPPER TROUGH THAT EXTENDS DOWN THE ERN MEXICO COASTLINE FROM 26N96W TO 19N98W. WEAK ANTI-CYCLONIC SURFACE FLOW IS AROUND THE HIGH PRESSURE CENTER ACROSS THE NE GULF WITH MAINLY E-SE WINDS OF 10-15 KT ACROSS THE REMAINDER OF THE BASIN. ALOFT...MAINLY ZONAL WLY FLOW DOMINATES WITH SOME CONVERGING SW AND NW WINDS BETWEEN THE BASE OF A LONGWAVE UPPER TROUGH OVER THE W ATLC AND AN UPPER LEVEL RIDGE OVER THE CARIBBEAN. WATER VAPOR IMAGERY ALSO INDICATES STRONG DRY AIR IN THIS CONVERGENCE ZONE. WITH A LONGWAVE UPPER RIDGE APPROACHING THE AREA...SURFACE RIDGING ALONG WITH MOSTLY FAIR WEATHER WILL REMAIN DURING THE NEXT DAY OR SO BEFORE THE NEXT UPPER TROUGH AND ASSOCIATED FRONTAL SYSTEM APPROACH THE AREA LATE MONDAY. SE RETURN FLOW IS EXPECTED TO INCREASE AHEAD OF THIS FRONT. CARIBBEAN SEA... THE CARIBBEAN ALSO REMAINS UNDER MOSTLY FAIR CONDITIONS UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE CENTERED JUST N OF ERN VENEZUELA NEAR 12N63W. MAINLY SWLY FLOW ALOFT COVERS THE WRN HALF OF THE BASIN AROUND THIS UPPER RIDGE WHICH IS DRAWING UPPER LEVEL MOISTURE FROM THE E PACIFIC ACROSS THIS PORTION OF THE BASIN SUPPORTING HIGH CLOUDS. THE ERN HALF OF THE BASIN IS UNDER THE INFLUENCE OF VERY DRY AIR WHICH IS SUPPORTING CLEAR SKIES. FRESH ELY TRADEWINDS ARE ACROSS THE MAJORITY OF THE BASIN. TOTAL PRECIPITABLE WATER IMAGERY SHOWS ENHANCED MOISTURE OVER THE NW CARIBBEAN AND OFF THE COASTS OF PANAMA AND COSTA RICA. WHILE NO EVIDENCE OF SHOWERS IS PRESENT AT THIS TIME...THE POSSIBILITY OF ISOLATED SHOWERS REMAINS DUE TO THIS ENHANCED MOISTURE. EXPECT LITTLE CHANGE OVER THE NEXT 24 HRS. ATLANTIC OCEAN... A DEEP LAYER TROUGH IS IMPACTING THE W ATLC WITH A LONGWAVE UPPER TROUGH OFF THE ERN SEABOARD ALONG 75W SUPPORTING A COLD FRONT WHICH ENTERS THE DISCUSSION AREA NEAR 32N54W CONTINUING SW TO THE SE BAHAMAS NEAR 23N74W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90 NM EITHER SIDE OF THE FRONT N OF 27N. POSSIBLE ISOLATED SHOWERS ARE ALONG THE REMAINDER OF THE FRONT. FARTHER E...A BROAD SURFACE RIDGE COVERS THE MAJORITY OF THE CENTRAL AND ERN ATLC ANCHORED BY A 1028 MB HIGH NEAR 30N35W WHICH IS PROVIDING MOSTLY FAIR CONDITIONS ACROSS THE AREA. ALOFT...AN UPPER LEVEL RIDGE EXTENDS NE FROM THE ERN CARIBBEAN TO THE AZORES ISLANDS. THE FAR E ATLC IS COVERED BY AN UPPER LEVEL TROUGH WITH AXIS EXTENDING W OF PORTUGAL ACROSS THE MADEIRA ISLANDS WITH A PORTION THEN EXTENDING SW TO NRN SOUTH AMERICA NEAR 7N55W. UPPER LEVEL MOISTURE IS BEING DRAWN NE AROUND THE ERN SIDE OF THE TROUGH SUPPORTING HIGH CLOUDS NEAR AND N OF THE WRN HALF OF THE ITCZ. THIS UPPER TROUGH ALSO SUPPORTS A FRONTAL SYSTEM ACROSS SPAIN AND INTO NW AFRICA. BROAD UPPER RIDGING COVERS THE TROPICAL ATLC S OF 17N E OF 43W. EXPECT THE FRONTAL SYSTEM IN THE W ATLC TO CONTINUE TO MOVE EWD OVER THE NEXT COUPLE OF DAYS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON