000 AXNT20 KNHC 122353 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON MAR 12 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 2315 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF LIBERIA NEAR 5N9W TO 5N10W. THE ITCZ CONTINUES FROM 5N10W ALONG 1N20W CROSSING THE EQUATOR AT 32W TO THE COAST OF BRAZIL AT 4S44W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 2N-6N BETWEEN 8W-18W. SCATTERED MODERATE CONVECTION IS FROM EQ-4N BETWEEN 18W-26W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3S-2N BETWEEN 34W-43W. ...DISCUSSION... GULF OF MEXICO... MAINLY W-SW FLOW ALOFT COVERS THE GULF OF MEXICO THIS EVENING AROUND AN UPPER LEVEL RIDGE THAT HAS SHIFTED EWD OVER THE PAST 24 HOURS AND IS NOW ALONG THE ERN SEABOARD. AN UPPER LEVEL TROUGH IS N OF THE AREA SUPPORTING A LOW PRESSURE SYSTEM WHICH REMAINS TO THE N. HOWEVER...A FEW STRONG SHOWERS/THUNDERSTORMS ARE ALONG THE GULF COASTLINE FROM THE FLORIDA PANHANDLE TO LOUISIANA BETWEEN 87W-93W. THE REMAINDER OF THE BASIN IS UNDER MOSTLY CLEAR SKIES DUE TO SURFACE RIDGING EXTENDING FROM A 1032 MB HIGH IN THE W ATLC NEAR 34N70W. A FEW ISOLATED SHOWERS ARE IN THE SE GULF AND THE FLORIDA STRAITS AS SOME MOISTURE STREAMS IN FROM THE ATLC. E-SE WINDS COVER MUCH OF THE BASIN RANGING FROM 15-20 KTS IN THE ERN GULF TO 5-10 KTS IN THE WRN GULF. EXPECT SURFACE RIDGING TO REMAIN ACROSS THE BASIN FOR THE NEXT SEVERAL DAYS. CARIBBEAN SEA... DRY AIR IS COVERING MUCH OF THE CARIBBEAN IN MAINLY WLY FLOW ALOFT PROVIDING MOSTLY FAIR CONDITIONS. SOME UPPER LEVEL MOISTURE IS PRESENT OVER THE FAR SE CARIBBEAN AS THE FLOW BECOMES SWLY AROUND AN UPPER LEVEL RIDGE COVERING THE WRN TROPICAL ATLC E OF THE LESSER ANTILLES. THE MOISTURE IN THIS AREA HAS DIMINISHED SINCE YESTERDAY AS THE RIDGE HAS SHIFTED E...BUT ISOLATED SHOWERS STILL REMAIN OVER MUCH OF THE WINDWARD ISLANDS. AT THE SURFACE...TRADEWIND FLOW OF 15-20 KTS IS ACROSS MUCH OF THE BASIN REACHING 30 KTS NEAR THE COAST OF COLOMBIA. A FEW PATCHES OF SHOWERS/THUNDERSTORMS ARE NOTED OVER THE NRN ISLANDS INCLUDING JAMAICA...HISPANIOLA...AND PUERTO RICO. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... AN UPPER LEVEL RIDGE WITH AXIS UP THE ERN SEABOARD SUPPORTS A 1032 MB HIGH OVER THE W ATLC NEAR 34N70W PROVIDING MOSTLY FAIR CONDITIONS. A FEW LINES OF MOISTURE ARE STREAMING AROUND THE RIDGE INCLUDING ALONG A LINE FROM 24N60W TO 28N69W...AND ACROSS THE BAHAMAS AND FLORIDA STRAITS ALONG 22N70W TO 24N81W. ISOLATED SHOWERS ARE WITHIN 50 NM OF THESE LINES. AN UPPER LEVEL TROUGH COVERS THE CENTRAL ATLC WITH MAIN AXIS DOWN 45W TO THE N OF 25N. THE UPPER TROUGH SUPPORTS A 1009 MB LOW JUST N OF THE DISCUSSION AREA NEAR 34N46W. AN ASSOCIATED COLD FRONT DIPS S FROM THE LOW CENTER ALONG 30N47W 22N57W. MOST OF THE SHOWER ACTIVITY IS E OF THE SYSTEM IN THE AREA OF STRONGEST DIFFLUENCE ALOFT. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE N OF 24N BETWEEN 41W-47W. THE ERN ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1027 MB HIGH NEAR 36N31W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 29W. UPPER LEVEL RIDGING ALSO COVERS THE TROPICAL ATLC CENTERED NEAR 1N38W. A BROAD UPPER TROUGH EXTENDS INTO THE ERN TROPICAL ATLC ALONG 20W S OF 23N. SOME UPPER LEVEL MOISTURE IS STREAMING AROUND THE WRN SIDE OF THE UPPER RIDGE ACROSS THE SRN WINDWARD ISLANDS TO NEAR 18N44W. POSSIBLE ISOLATED SHOWERS ARE WITHIN THIS REGION. THE LAST VISIBLE SATELLITE IMAGES OF THE DAY ALSO INDICATE A PLUME OF DUST EXTENDING FROM THE AFRICAN COAST TO 42W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON