000 AGXX40 KNHC 301804 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 200 PM EDT WED MAR 30 2011 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... RADAR AND LIGHTNING DATA SHOW CLUSTERS OF THUNDERSTORMS MIGRATING ACROSS THE FAR NE GULF WATERS CURRENTLY...AHEAD OF A DYNAMIC SHORT WAVE TROUGH MOVING OVER THE LOWER MISSISSIPPI VALLEY. A FOLLOWING COLD FRONT EXTENDS ACROSS THE NW GULF...FROM VERMILION BAY LOUISIANA TO JUST SOUTH OF BROWNSVILLE TEXAS. BUOYS AND LAND BASED OBSERVATIONS WERE SHOWING 20 TO 25 KT NORTHERLY WINDS BEHIND THE FRONT THIS MORNING...BUT THIS IS STARTING TO DIMINISH. WINDSAT DATA ARE SHOWING 20 KT SOUTHERLY FLOW OVER THE N CENTRAL GULF...CONVERGING INTO THE LOW OVER THE NE GULF. THE FRONT WILL WEAKEN AS IT MOVES INTO THE SE GULF OVER THE NEXT DAY AND A HALF...WITH THE SUPPORTING UPPER TROUGH DEAMPLIFYING AS IT MOVES FROM THE CENTRAL PLAINS THROUGH THE CAROLINAS. HIGH PRES WILL BUILD W TO E ACROSS THE CENTRAL GULF FRI AND SAT BEHIND THE DECAYING FRONT. N OF THE RIDGE...A SECOND FRONT WILL SAG INTO THE NE GULF LATE FRI AND SAT...BUT STALL AND SHIFT N AGAIN BY SAT NIGHT IN RESPONSE TO DEEPENING LOW PRES OVER THE CENTRAL PLAINS. FRESH SE TO S FLOW WILL SET UP OVER THE WESTERN GULF LATE SAT...THEN SPREAD OVER MOST OF THE GULF THROUGH MON AS THE STRONG SURFACE LOW SHIFTS THROUGH THE MID MISSISSIPPI VALLEY. AN ASSOCIATED COLD FRONT WILL PUSH INTO THE NW GULF BY LATE MON NIGHT. CARIBBEAN AND TROP N ATLC W OF 55W... THE COMBINATION OF TROUGH OVER THE WESTERN GULF AND HIGH PRES OVER THE WESTERN ATLC IS RESULTING IN FRESH TO STRONG TRADES OVER THE EASTERN AND CENTRAL CARIBBEAN AND FRESH SE WINDS OVER THE NW CARIBBEAN. A WEAK SURFACE TROUGH ALONG THE LESSER ANTILLES WILL MOVE W BUT DAMPEN OUT THROUGH 36 HOURS. WINDS OVER THE WESTERN CARIBBEAN WILL DIMINISH THU THROUGH SAT AS A WEAK COLD FRONT MOVES INTO THE SOUTHERN GULF AND BECOMES DIFFUSE. FRESH TO STRONG WINDS WILL PERSIST FROM THE TROP N ATLC THROUGH THE CENTRAL CARIBBEAN THROUGH MON AS HIGH PRES REMAINS N OF THE AREA. SE WINDS OVER THE NW CARIBBEAN INCLUDING THE GULF OF HONDURAS WILL INCREASE SUN AND MON...IN RESPONSE TO TROUGHING TO THE NW AND HIGH PRES TO THE NE. CENTRAL ATLC HIGH PRES FORCES STRONG SE BREEZE ACROSS NW ZONE AND FRESH E TO SE WINDS ELSEWHERE OVER CARIBBEAN...EXCEPT ALONG COAST OF COLOMBIA WHERE IT REMAINS STRONG WITH 9 FT SEAS PREVAILING. WINDS DIMINISH THU THROUGH SAT AS WEAK COLD FRONT MOVES INTO SOUTHERN GULF AND BECOMES DIFFUSE. FRESH TO STRONG WINDS PERSIST FROM TROP N ATLC THROUGH CENTRAL CARIBBEAN THROUGH SUN AS HIGH PRES REMAINS N OF AREA. SW N ATLC... THE MAIN ISSUE CONTINUES TO BE THE PROBABILITY OF WINDS REACHING GALE FORCE N OF 30N IN THE WATERS BETWEEN N FLORIDA AND BERMUDA TONIGHT...THEN AGAIN ON THU EVENING. A LOW PRES CENTER OVER N CENTRAL GULF OFF THE WESTERN FLORIDA PANHANDLE WILL MERGE WITH ANOTHER LOW OVER THE LOWER MISSISSIPPI VALLEY...THEN DEEPEN AS THEY SHIFT NE TO THE NC OUTER BANKS TONIGHT. A TRAILING COLD FRONT WILL MOVE OFF THE N FLORIDA COAST THU NIGHT. OPERATIONAL GFS SHOWS SW FLOW AHEAD OF THE FRONT AND S OF THE LOW REACHING GALE FORCE N OF 30N NEAR 76W THIS AFTERNOON. 06Z ENSEMBLE GFS ALONG WITH THE 09Z SREF BOTH SHOW A BRIEF 20 PERCENT CHANCE OF GALES IN THIS AREA AROUND LATE AFTERNOON. CURRENT THINKING IS THAT GALES WILL REMAIN N OF THE FORECAST AREA FOR THIS TIME PERIOD...ALTHOUGH IT REMAINS CLOSE. A SECOND LOW PRES WILL FOLLOW THE FIRST INTO THE CAROLINAS. OPERATIONAL GFS FROM 06Z AND 00Z ECMWF INDICATE SW WINDS TO GALE FORCE BY THU EVENING DIRECTLY AHEAD OF THE COLD FRONT. SREF AND GFS ENSEMBLE OUTPUT ALSO HINTS OF A LOW CHANCE OF GALES FOR THIS TIME FRAME. AS WITH WED EVENING EVENT...THE BETTER CHANCE FOR GALES REMAINS N OF THE AREA. THE FRONT WILL STALL AND BECOME DIFFUSE FROM 31N65W TO S FLORIDA BY LATE FRI...AS A SECOND REINFORCING FRONT SAGS S OF 30N. THE SECOND FRONT WILL EXTEND FROM 28N65W TO CENTRAL FLORIDA BY EARLY SUN. GLOBAL MODELS AGAIN HINT AT A LOW CHANCE OF GALES AHEAD OF THIS FRONT LATE SAT...WITH THE BEST CHANCE WELL TO THE N. THE FRONT BECOMES DIFFUSE EARLY MON FROM 24N65W TO 27N74W. HIGH PRES BUILDS OVER THE AREA N OF 28N MON...WITH FRESH TRADES S OF 22N AND MODERATE TO FRESH SOUTHERLY RETURN FLOW N OF THE NORTHERN BAHAMAS BY LATE MON. WARNINGS.. ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER CHRISTENSEN