000 AGXX40 KNHC 280551 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 200 AM EDT SAT APR 28 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... HIGH PRES CENTERED NEAR CEDAR KEY FL RIDGES W TO THE NE TX COAST. SLY RETURN FLOW IS AT 15-20 KT...LOCALLY 25 KT...OVER WATERS W OF 90W WHILE ELY WINDS CONTINUE AT 15-20 KT THROUGHOUT THE FL STRAITS. THE SURFACE HIGH WILL SHIFT N OVER THE FL PANHANDLE TODAY WITH THE RIDGE EXTENDING W ALONG 31N LATE TONIGHT. THE RIDGE WILL RE-ORIENTATE NE-SW FROM THE CAROLINAS TO N TX ON MON AND TUE...THEN SHIFT S AGAIN AND EXTEND E-W ALONG 32N ON WED. AN INVERTED TROUGH EXTENDS NORTHWARD FROM THE CARIBBEAN ACROSS THE CAY SAL BANK. GUIDANCE SUGGESTS THAT THIS BROAD TROUGH WILL DRIFT W ACROSS THE BAHAMA CHANNEL AND FL TO THE S OF 26N TONIGHT AND SUN...AND INTO THE E GULF WATERS LATE SUN NIGHT...REACHING ALONG 88W TUE...THEN WEAKENING OVER THE WESTERN GULF WATERS ON WED. THE GFS AND ECM ARE FAIRLY CLOSE ON THE TIMING...HOWEVER THE GFS IS MORE AGGRESSIVE AND STRENGTHENS THE LOW LEVEL WINDS TO 30 KT JUST W OF THE TROUGH AXIS. I WILL USE A BLEND OF GFS AND ECM...WITH WINDS MAXING AT 25 KT. A SURFACE LOW MAY DEVELOP ALONG THE TROUGH AXIS THROUGHOUT THE FORECAST CYCLE. SW N ATLC FROM 19N TO 31N W OF 55W... A LOW LEVEL TROUGH DIVIDES THE SUBTROPICAL ATLC RIDGE WITH THE WESTERN SEGMENT EXTENDING FROM BERMUDA TO NE FL ATTM. THE RIDGE WILL SHIFT N TODAY AND EXTEND E-W ALONG 31N LATE TONIGHT...THEN FURTHER WEAKEN AS A WEAK COLD FRONT SWEEPS SE PASSING OF BERMUDA LATE SUN NIGHT...AND ACROSS THE NE WATERS MON...AND E OF 55W ON MON NIGHT. ELY WINDS ARE CURRENTLY AT 15-20 KT ACROSS ALL WATERS S OF 25N TO THE E OF AN INVERTED TROUGH AMPLIFYING NORTHWARD FROM THE CARIBBEAN ACROSS THE CAY SAL BANK AND THE BAHAMA CHANNEL. THE TROUGH WILL STRENGTHEN TODAY AND TONIGHT AND MOVE W ACROSS FL AND THE FL STRAITS ON SUN. THE ELY WINDS WILL DIMINISH BELOW 20 KT FROM THE E ON MON AND TUE AND BE LESS THAN 20 KT ALL WATERS BY MIDDAY WED. CARIBBEAN SEA AND TROPICAL ATLC S OF 19N W OF 55W... A BROAD TROUGH OVER THE CARIBBEAN TO THE W OF 72W HAS ITS MEAN AXIS TO THE N OF 12N ALONG 80W AT THE MOMENT. THE TROUGH AXIS WILL MOVE W TO ALONG 83W LATE MON AND BE WELL W OF AREA EARLY TUE NIGHT. ELY TRADES ENHANCED TO 15-20 KT E OF 72W WILL CHANGE LITTLE THROUGH EARLY MON...THEN DIMINISH SOME TUE AND 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... .NONE. ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER NELSON