000 AXNT20 KNHC 112357 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED APR 11 2012 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2300 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF LIBERIA AT 6N11W TO THE EQUATOR AND 23W. THE ITCZ CONTINUES FROM EQ23W TO 1S28W CONTINUING BACK NWD TO THE EQUATOR AT 38W...AND BACK S AGAIN TO THE COAST OF BRAZIL AT 3S45W. SCATTERED MODERATE/STRONG CONVECTION IS OFF THE COAST OF AFRICA FROM 2S-7N BETWEEN 11W-20W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 1N-3N BETWEEN 29W-33W. ...DISCUSSION... THE GULF OF MEXICO... MOSTLY DRY AIR IN W-NW FLOW ALOFT COVERS THE GULF OF MEXICO THIS EVENING AROUND THE E SIDE OF AN UPPER LEVEL RIDGE COVERING THE CENTRAL CONUS ALONG 99W...AND THE W SIDE OF A BROAD UPPER LEVEL TROUGH COVERING THE ERN CONUS AND W ATLC ALONG 81W. THE UPPER RIDGE SUPPORTS A WEAK SURFACE RIDGE ACROSS THE NRN GULF AROUND A 1021 MB HIGH S OF LOUISIANA AT 28N91W. LIGHT ANTI-CYCLONIC FLOW IS AROUND THE HIGH CENTER WITH STRONGER RETURN FLOW ALONG THE TEXAS COAST. SKIES ARE MOSTLY CLEAR WITH A FEW WIDELY ISOLATED LOW-LEVEL CLOUDS OVER THE SE GULF AND FAR SW GULF WITH POSSIBLE ISOLATED SHOWERS. AN AREA OF SCATTERED SHOWERS/THUNDERSTORMS IS ALSO OVER SRN LOUISIANA ASSOCIATED WITH A STATIONARY FRONT THAT DRAPES ACROSS TEXAS TO LOUISIANA. EXPECT THE WEAK SURFACE HIGH OVER THE NRN GULF TO DISSIPATE OVER THE NEXT 24 HOURS AS A SURFACE HIGH TO THE N BUILDS S PROVIDING RIDGING ACROSS THE AREA. RETURN FLOW ALONG THE WRN IS ALSO EXPECTED TO INCREASE TO 20-25 KTS BY THE END OF THE WEEK AND THROUGH THE WEEKEND. THE CARIBBEAN SEA... DRY AIR ALOFT IN ZONAL WLY FLOW IS PROVIDING FAIR CONDITIONS ACROSS MUCH OF THE CARIBBEAN WATERS. HOWEVER...A SURFACE TROUGH EXTENDS ACROSS THE CENTRAL CARIBBEAN FROM S OF ERN CUBA AT 19N76W ACROSS JAMAICA TO 13N79W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE MAINLY N OF THE AXIS ACROSS ERN CUBA WITH MORE ISOLATED ACTIVITY OVER JAMAICA AND W OF JAMAICA FROM 18N-19N BETWEEN 79W-83W. A SECOND SURFACE TROUGH TO THE N OF HISPANIOLA IS ALSO BRINGING SHOWERS/THUNDERSTORMS TO THE ISLAND. ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE ALSO MOVING THROUGH THE LESSER ANTILLES ASSOCIATED WITH AN AREA OF LOW-LEVEL MOISTURE ADVECTING WWD FROM THE TROPICAL ATLC. BESIDES NEAR THE SURFACE TROUGH...THE REMAINDER OF THE AREA IS UNDER TRADEWIND FLOW OF 10-15 KTS WITH MOSTLY CLEAR SKIES. EXPECT THE SURFACE TROUGH TO REMAIN SOMEWHAT STATIONARY AND GRADUALLY DISSIPATE WITH THE TROUGH N OF HISPANIOLA ALSO REMAINING STATIONARY BEFORE BEING SWEPT UP BY A FRONTAL BOUNDARY OVER THE W ATLC. ENHANCED LOW-LEVEL MOISTURE WILL ALSO REMAIN OVER THE NRN CARIBBEAN INCREASING THE CHANCE FOR CONTINUED RAINFALL ACROSS THE NRN ISLANDS. THE ATLANTIC OCEAN... A LONGWAVE UPPER TROUGH COVERS THE ERN CONUS AND W ATLC ALONG 81W SUPPORTING A COLD FRONT THAT HAS DIPPED S INTO THE AREA ALONG 32N73W TO THE COAST OF FLORIDA AT 28N81W TO 28N83W...AS OF 2100 UTC. A LINE OF SHOWERS/THUNDERSTORMS IS E OF THE FRONT AXIS FROM 28N75W TO 32N70W CONTINUING N OF THE AREA. A SURFACE TROUGH IS N OF HISPANIOLA ALONG 20N71W TO 27N69W SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS OVER HISPANIOLA WITH SIMILAR ACTIVITY N OF THE AXIS FROM 27N-31N BETWEEN 64W-69W. AN AREA OF SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS IS ALSO E OF THE AXIS FROM 22N-28N BETWEEN 60W-69W. SOME OF THIS ACTIVITY IS ALSO INFLUENCED BY A SECOND FRONTAL BOUNDARY TO THE E. A STATIONARY FRONT ENTERS THE DISCUSSION AREA AT 32N53W TO 28N57W WHERE IT CONTINUES AS A DISSIPATING WARM FRONT TO 26N62W. THE SURFACE TROUGH IS EXPECTED TO REMAIN STATIONARY BEFORE BEING SWEPT UP BY THE COLD FRONT TO THE W. A BROAD UPPER RIDGE COVERS MUCH OF THE CENTRAL AND ERN ATLC WITH AXIS EXTENDING FROM E OF THE LESSER ANTILLES TO W OF THE AZORES ISLANDS NEAR 47N33W. THE UPPER RIDGE IS SUPPORTING SURFACE RIDGING AROUND A 1031 MB HIGH NEAR 38N37W...WHICH IS PROVIDING FAIR WEATHER ACROSS MUCH OF THE ERN ATLC. A NARROW UPPER LEVEL TROUGH COVERS THE FAR ERN ATLC WITH AXIS FROM PORTUGAL TO THE CANARY ISLANDS TO THE CAPE VERDE ISLANDS. THE UPPER TROUGH IS SUPPORTING SEVERAL SURFACE LOWS OVER LAND INCLUDING OVER NW AFRICA...SPAIN AND N OF SPAIN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON