000 AXNT20 KNHC 031131 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED FROM THE SRN COAST OF LIBERIA NEAR 5N9W ALONG 2N20W 1N30W CROSSING THE EQUATOR NEAR 37W AND INTO NE BRAZIL TO NEAR 2S46W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-6N BETWEEN 12W-16W. SIMILAR ACTIVITY IS WITHIN 130 NM S OF THE AXIS BETWEEN 13W-16W...WITHIN 170 NM N OF THE AXIS BETWEEN 20W-32W...AND FROM 1S-3N BETWEEN 45W-49W. ...DISCUSSION... GULF OF MEXICO... THE GULF OF MEXICO REMAINS MOSTLY CLEAR UNDER THE INFLUENCE OF SURFACE RIDGING AROUND A 1019 MB HIGH CENTERED S OF THE FLORIDA PANHANDLE NEAR 28N85W. PATCHES OF LOW-LEVEL CLOUDS ARE ACROSS THE WRN HALF OF THE BASIN WITH FOG OVER SE TEXAS INDICATED BY SURFACE OBSERVATIONS AND SATELLITE DATA. A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE IN THE FAR SW GULF FROM 17N-23N BETWEEN 95W-97W INDICATED BY LIGHTNING DATA. THESE STORMS ARE ASSOCIATED WITH A DAMPENING SHORTWAVE UPPER TROUGH THAT EXTENDS FROM 27N94W TO 23N97W. 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...NWLY WINDS ARE ACROSS THE NRN GULF AROUND THE ERN SIDE OF AN APPROACHING UPPER RIDGE WITH SWLY WINDS ACROSS THE SRN GULF AROUND ANOTHER UPPER LEVEL RIDGE CENTERED OVER THE ERN CARIBBEAN. WATER VAPOR IMAGERY INDICATES STRONG DRY AIR IN THE CONVERGENCE ZONE BETWEEN THE NWLY AND SWLY WINDS. THE SWLY WINDS ALOFT ARE ALSO DRAWING SOME E PACIFIC MOISTURE ACROSS THE SRN GULF SUPPORTING HIGH CLOUDS. WITH THE 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. LIGHTNING DATA INDICATES A LINE OF SHOWERS/THUNDERSTORMS JUST OFF THE COAST OF COSTA RICA DUE TO THE COMBINATION OF ENHANCED MOISTURE AND WIND CONVERGENCE ALONG THE COASTLINE. 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 70W SUPPORTING A COLD FRONT WHICH ENTERS THE DISCUSSION AREA NEAR 32N53W CONTINUING SW TO THE SE BAHAMAS NEAR 23N73W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 45 NM EITHER SIDE OF THE FRONT N OF 26N...WITH SCATTERED SHOWERS ALONG THE FRONT ELSEWHERE. A WEAK 1018 MB HIGH IS NOTED BEHIND THE FRONT NEAR THE NE BAHAMAS PROVIDING FAIR CONDITIONS IN THE WAKE OF THE FRONT. FARTHER E...A BROAD SURFACE RIDGE COVERS THE MAJORITY OF THE CENTRAL AND ERN ATLC ANCHORED BY A [PAIR OF 1026 MB HIGHS NEAR 31N28W AND 29N37W 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 7N53W. 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