000 AXNT20 KNHC 212308 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON MAR 21 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2300 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 06N10W 00N20W 01S35W 01S46W CROSSING 46W INTO SOUTH AMERICA. ISOLATED MODERATE CONVECTION IS OCCURRING FROM 05S TO 03N BETWEEN 14W AND 22W. ...DISCUSSION... GULF OF MEXICO... AS OF 2100 UTC...A 1025 MB SURFACE HIGH WAS LOCATED IN THE NE GULF OF MEXICO NEAR 29N85W. STABLE CONDITIONS PREVAIL IN THE POST-FRONTAL AIRMASS WITH NO DEEP CONVECTION OCCURRING. SOME SHOWERS ARE SEEN IN WESTERN CUBA ALONG THE TAIL END OF THE DECAYING COLD FRONT BOUNDARY. A SECOND AREA OF LOW-TOPPED RAINFALL IS OBSERVED IN THE BAY OF CAMPECHE ALONG THE CONVERGENCE OF EASTERLIES COMING ACROSS THE YUCATAN OF MEXICO AND NORTHERLIES FUNNELING ACROSS THE CHIVELA PASS. SURFACE WINDS ARE GENERALLY EASTERLY TO SOUTHEASTERLY 20 KT OR LESS. IN THE UPPER LEVELS...SUBSIDENT RIDGING DOMINATES OVER THE CENTRAL GULF OF MEXICO WITH SOME HIGH CLOUDINESS ADVECTING OVER THE NORTHERNMOST GULF FROM CONVECTION FORMING OVER NORTH MEXICO. DURING THE NEXT DAY...LITTLE CHANGE IS EXPECTED IN THESE CONDITIONS. CARIBBEAN SEA... A DISSIPATING FRONTAL BOUNDARY HAS REACHED CUBA TODAY WITH MINIMAL COOL AIR BUT SCATTERED SHOWERS ALONG THE NORTHERN HALF OF THE ISLAND...AS SEEN FROM THE CUBAN RADAR NETWORK. SOME LOW-TOPPED RAINFALL IS ALSO OCCURRING OVER THE NORTH AND EAST FACING SLOPES OF JAMAICA...HISPANIOLA AND PUERTO RICO. AS IS TYPICAL FOR THIS TIME OF YEAR...NO DEEP CONVECTION IS OBSERVED ACROSS THE CARIBBEAN OR CENTRAL AMERICA. A MODERATE PRESSURE GRADIENT BETWEEN A 1028 MB HIGH NEAR 34N72W OFF OF THE U.S. CAROLINAS AND LOW PRESSURE OVER SOUTH AMERICA IS PRODUCING 15 TO 25 KT NE SURFACE TRADEWINDS. IN THE UPPER LEVELS... ANTICYCLONICALLY-TURNING SOUTHWESTERLY WINDS PREVAIL...WHICH ARE ADVECTING SOME HIGH CLOUDINESS OVER THE SOUTHERN AND EASTERN PORTION OF THE CARIBBEAN FROM DEEP CONVECTION OVER SOUTH AMERICA. DURING THE NEXT DAY...LITTLE CHANGE IS EXPECTED IN THESE CONDITIONS. ATLANTIC OCEAN... THE MAIN FEATURE OF INTEREST IS A COLD FRONT THAT EXTENDS FROM 32N45W SOUTHWESTWARD TO 22N60W AND WESTWARD TO 22N72W NEAR THE TURKS AND CAICOS. FROM THERE THE BOUNDARY CONTINUES WESTWARD AS A DISSIPATING COLD FRONT INTO CUBA. PEAK WINDS NEAR 30N JUST WEST OF THE FRONT ARE AT 30 KT...THE ONE GALE REPORT OF 36 KT NNW WIND FROM SHIP WCPU APPEARS TO BE BIASED ABOUT 5 KT TOO HIGH. ELSEWHERE BEHIND THE FRONT...WINDS ARE NORTHERLY 15 TO 25 KT. NO DEEP CONVECTION IS OCCURRING IN ASSOCIATION WITH THE FRONT THOUGH SOME SHOWERS ARE BEING GENERATED WITHIN 120 NM OF THE FRONTAL BOUNDARY. HOWEVER...A LARGE AREA OF SCATTERED SHOWERS WITHIN 240 NM E OF A PRE-FRONTAL TROUGH AXIS ARE SEEN IN THE GEOSTATIONARY SATELLITE IMAGERY. THE TROUGH EXTENDS FROM 29N44W TO 25N42W TO 15N49W. SURFACE WINDS EAST OF THE TROUGH ARE ENHANCED WITH 20 TO 30 KT SE WINDS. A WEAK 1018 MB SURFACE HIGH IS AT 28N28W...WEST OF THE CANARY ISLANDS. BECAUSE OF THE WEAK HIGH...THE PRESSURE GRADIENT IS RELAXED WITH SURFACE WINDS THROUGHOUT MOST OF THE TROPICAL AND SUBTROPICAL NORTH ATLANTIC QUITE WEAK...5 TO 15 KT. IN THE UPPER LEVELS...A TROUGH EXTENDS FROM NORTH OF OUR AREA SOUTHWARD TO 32N48W TO 28N48W...WHICH IS PROVIDING SOME UPPER LEVEL SUPPORT FOR THE FRONT AND THE SURFACE TROUGH. ELSEWHERE...ZONAL WESTERLY FLOW PREVAILS NORTH OF A RIDGE EXTENDING ALONG ROUGHLY 07N ACROSS THE EQUATORIAL ATLANTIC. DURING THE NEXT DAY...THE FRONTAL BOUNDARY SHOULD CONTINUING MOVING SOUTHEASTWARD WITH THE PRE-FRONTAL TROUGH RETAINING ITS IDENTITY AHEAD OF THE FRONT. THE COLD FRONT SHOULD BECOME ILL-DEFINED WEST OF 65W...BUT MAY CONTINUE TO CAUSE SOME SHOWERS OVER THE GREATER ANTILLES. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LANDSEA