000 AGXX40 KNHC 210752 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 350 AM EDT SAT APR 21 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... THE UPPER TROUGH HAS PUSHED SEWD TOWARDS NE TEXAS...AND APPEARS RATHER VIGOROUS ON WATER VAPOR IMAGERY EARLY THIS MORNING. ITS ASSOCIATED COLD FRONT MOVED OFFSHORE THE TEXAS COAST LAST NIGHT AS WAS FORECAST. IT IS MAKING HEADWAY OVER THE FAR WRN GULF WATERS EARLY THIS MORNING AS IT EXTENDS FROM SW LOUISIANA TO FAR SE TEXAS. A SURFACE TROUGH EXTENDS FROM 29N86W SSW TO INLAND THE YUCATAN PENINSULA. BUOY AND OIL PLATFORMS SHOW SE-S WINDS OF 10-15 KT ELSEWHERE ACROSS THE GULF. AN ASCAT PASS FROM LAST NIGHT OVER THE CENTRAL GULF CORROBORATED WELL WITH THE OBSERVED WIND SPEEDS AND DIRECTIONS. SEAS ARE IN THE RANGE OF 2-4 FT... BUT BUILDING QUITE RAPIDLY BEHIND THE FRONT. BOTH SATELLITE AND RADAR DATA FROM LAST NIGHT AND EARLY THIS MORNING REVEAL SCATTERED TO NUMEROUS TSTM ACTIVITY WITH FREQUENT LIGHTNING OVER THE CENTRAL GULF AND WRN GULF PORTIONS N OF 23N BETWEEN THE COLD FRONT AND 89W...AND E OF THE SURFACE TROUGH FROM 23N TO 28N. AS FOR THE FORECAST...NWP MODELS ARE IN GOOD AGREEMENT WITH FORECAST PSNS OF THE FRONT AS IT PUSHES E ACROSS THE REMAINDER OF THE GULF IN THE VERY NEAR SHORT TERM. SIMILARLY TO YESTERDAY...WILL RELY MAINLY ON GUIDANCE FROM THE ECMWF AND NAM MODELS FOR THIS FORECAST AS PREFER THEIR CLEANER DEPICTIONS OF THE FRONT RACING ACROSS THE GULF. BASED ON THIS WILL FORECAST THE COLD FRONT TO REACH A PSN FROM NEAR THE MOUTH OF THE MISSISSIPPI RIVER TO THE WRN BAY OF CAMPECHE LATER THIS MORNING WITH LOW PRES DEVELOPING ON THE NRN PORTION OF FRONT IN THE N CENTRAL GULF NEAR A LOCATION OF 28N90W ATTAINED BY TAKING THE MEAN OF TWO LOWS SHOWN BY THE NAM WITH THE SECONDARY LOW NEAR 27N87W. WILL USE THE ECMWF INITIAL PRES OF 1006 MB AS ALSO SEEN IN THE GFS GUIDANCE. THE LOW AND TRACK ENE TO NEAR 28N86W 1004 MB BY EARLY TONIGHT WITH COLD FRONT TO EXTEND FROM IT SSW TO THE NW PART OF THE YUCATAN PENINSULA...THEN TRACK NE ACROSS N CENTRAL FLORIDA SUN PUSHING THE COLD FRONT SE ACROSS THE PENINSULA AND TO THE FAR SE GULF AND STRAITS OF FLORIDA BY IN THE AFTERNOON AND EARLY EVENING. NW WINDS OF 20-25 KT ARE FORECAST IN THE WAKE OF THE FRONT OVER MUCH OF THE ERN AND MIDDLE GULF PORTION INTO MON BEFORE DIMINISHING TO 15-20 KT. A REINFORCING SURGE OF NLY WINDS WILL SURGE INTO THE NORTHERN GULF MON THEN DIMINISH TUE AS HIGH PRES SETTLES IN OVER THE N CENTRAL GULF...ALLOWING SE RETURN FLOW WILL INCREASE OVER THE NW GULF WED. SW NORTH ATLC S OF 31N W OF 65W... THE OVERALL PATTERN OVER THE BASIN IS UNDERGOING CHANGES AS A RIDGE CURRENTLY EXTENDING FROM 28N65W TO THE STRAITS OF FLORIDA SHIFT NE THROUGH SUN NIGHT ALLOWING FOR THE ABOVE GULF OF MEXICO COLD FRONT TO MOVE INTO THE WRN PART OF THE ATLC AS THE ATTENDANT LOW PRES TRACKS NE WHILE DEEPENING. SCATTERED TO NUMEROUS SHOWERS AND TSTMS ARE ALREADY MOVING INTO THE FAR WRN WATERS N AND W OF THE BAHAMAS. THE TIGHTENING PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES OVER FLORIDA HAS ALLOWED FOR SLY WINDS TO INCREASE TO 15-20 KT N OF THE BAHAMAS. THESE WINDS WILL CONTINUE TO INCREASE WHILE SPREADING EWD THROUGH THE WEEKEND AHEAD OF THE APPROACHING GULF OF MEXICO FRONTAL SYSTEM. THESE SLY WINDS ARE FORECAST TO REACH 30 KT IN ZONES 111 AND 113 TONIGHT AND SUN AHEAD OF THE COLD FRONT. BRIEF GUSTS TO GALE FORCE ARE STILL POSSIBLE WITH THESE WINDS...BUT ARE FORECAST TO BE FREQUENT JUST N OF THE FORECAST WATERS WHERE GALE WARNINGS ARE ALREADY IN PLACE THERE BY OPC. SEAS IN THAT PART OF THE AREA ARE FORECAST TO BUILD UP TO 11 OR 12 FT SUN PER CONSENSUS OF GUIDANCE FROM THE VARIOUS WAVEWATCH MODELS. GUIDANCE FROM THE GLOBAL MODELS IS IN VERY CLOSE IN AGREEMENT FOR THE MEDIUM TO LONG TERM PERIODS OF THE FORECAST WITH RESPECT TO THE COLD FRONT PSNS AND RELATED WINDS. BASED ON THIS... WILL FORECAST THE FRONT TO ENTER THE FAR NW WATERS LATE TONIGHT AS THE ATTENDANT LOW TRACKS NE ALONG THE SE U.S. COAST WHILE DEEPENING INTO SUN. THE FRONT WILL REACH FROM NEAR 31N78W TO WRN CUBA BY EARLY SUN EVENING...FROM NEAR 31N74W TO CENTRAL CUBA BY EARLY MON MORNING...THEN BEGIN TO WEAKEN AS IT REACHES A PSN FROM NEAR 31N68W TO WINDWARD PASSAGE BY EARLY TUE MORNING...AND FROM 25N65W TO THE ERN PART OF THE DOMINICAN REPUBLIC BY EARLY WED MORNING. THE FRONT WILL THEN SLOWLY BECOME DIFFUSE E OF THE FORECAST WATERS LATER ON WED. WINDS AND SEAS DIMINISH OVER THE AREA BEHIND THE FRONT AS HIGH PRES BUILDS OVER THE CENTRAL PORTION OF THE FORECAST ATLC WATERS. CARIBBEAN SEA... BUOY OBSERVATIONS FROM THROUGHOUT THE BASIN ARE REPORTING NE-E WINDS OF 15 KT E OF 79W...AND SE WINDS OF 15 TO AT TIMES 20 KT W OF 70W. MAX SEAS HAVE LOWERED TO 6 FT IN THE SW PART OF THE CARIBBEAN. ELSEWHERE SEAS ARE IN THE RANGE OF 4-5 FT. NEAR TERM UPCOMING CHANGES WILL BE ATTRIBUTED TO THE CURRENT WRN GULF OF MEXICO COLD FRONT. HIGH PRES N OF THE AREA WILL SHIFT NE THROUGH SUN NIGHT ALLOWING FOR THE SRN PORTION OF THE COLD FRONT TO PUSH ESE AND INTO THE YUCATAN CHANNEL AND NW CARIBBEAN TONIGHT AS CONSISTENTLY DEPICTED BY THE NWP MODELS. PRIOR TO THIS... THE SE WINDS IN THE NW CARIBBEAN WILL BEGIN TO VEER AROUND TO THE S AND SW THIS MORNING AND AFTERNOON...AND INCREASE AS THE GULF OF MEXICO COLD FRONT APPROACHES THE NW PORTION. THE FRONT WILL BE FOLLOWED BY 20 KT W-NW WINDS. THE FRONT WILL REACH FROM WRN CUBA TO NEAR 18N86W BY EARLY SUN EVENING...THEN BEGIN TO WEAKEN AND GRADUALLY SLOW ITS FORWARD MOTION AS IT REACHES FROM CENTRAL CUBA TO GULF OF HONDURAS BY EARLY MON....FROM NEAR ERN CUBA AND THE WINDWARD PASSAGE TO NE HONDURAS BY EARLY TUE...AND BECOME DIFFUSE (BARELY A DISTINGUISHABLE FRONTAL FEATURE) IN THE NE PORTION LATER ON TUE INTO WED. HIGH PRES BEHIND THE FRONT WILL ALLOW FOR DIMINISHED NW-N 15 KT WINDS THROUGH THE YUCATAN CHANNEL TO GULF OF HONDURAS LATE MON...AND INTO MUCH OF TUE BEFORE VEERING AROUND TO THE NE-E LATER ON TUE AND WED AS HIGH PRES N OF THE AREA IN THE ERN GULF SHIFTS E. TROPICAL N ATLC S OF 19N W OF 55W... LIGHT NE-E WINDS PREVAIL THROUGHOUT...EXCEPT IN THE FAR SRN PORTION WHERE SLIGHTER STRONGER NE WINDS OF 15-20 KT ARE NOTED BY A COUPLE OF SHIP OBSERVATIONS AND AS HINTED BY A PARTIAL ASCAT PASS FROM LAST NIGHT. SEAS ARE IN THE RANGE OF 4-5 FT...EXCEPT TO 6 FT IN THE FAR SRN PORTION. LITTLE OVERALL CHANGE IS EXPECTED WITH THE CURRENT CONDITIONS THROUGH THE FORECAST PERIOD. THE COLD FRONT FEATURE DESCRIBED IN ABOVE SECTIONS SHOULD HAVE LITTLE IMPACT ON THIS PORTION OF THE ATLC AS IT APPROACHES THE FAR NW WATERS ON WED. NOTE... EFFECTIVE APR 3, 2012 AT 1800 UTC THE OFFSHORE WATERS FORECAST ZONES CHANGED FOR THE CARIBBEAN AND SW N ATLANTIC AND THE GULF OF MEXICO. ISSUANCE TIME FOR THE GULF OF MEXICO OFFSHORE WATERS FORECASTS IS REFERENCED TO THE EASTERN TIME ZONE. FOR DETAILS SEE WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF GRIDDED MARINE OUTPUT IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE (LOWER CASE). GULF OF MEXICO... .NONE. .CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. .SW N ATLC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE