000 AGXX40 KNHC 231736 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 140 PM EDT MON APR 23 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... A SECONDARY N SURGE...ANALYZED AS A COLD FRONT..IS IDENTIFIED BY A LINE OF LOW CLOUDS RACING SE AND ACCOMPANIED BY AN INCREASE IN N FLOW TO 20-25 KT AS PREVIOUSLY FORECAST OVER WATERS N OF 26N E OF 95W. EXPECT THIS BOUNDARY...AND ITS SLIGHTEST WIND SHIFT...TO BE DIFFICULT TO LOCATE WITHIN A FEW HOURS THUS DROPPED MENTION IN THIS MORNINGS TEXT FORECAST. ALTHOUGH N WINDS ARE DIMINISHING STILL HAVE REPORTS TO 20 KT OVER GULF S OF 26N E OF 90W...WITH SEAS STILL MAXING AT 11 FT...PRIMARILY DUE TO THE SUBSIDING NW SWELL. WINDS WILL DIMINISH BELOW 20 KT ALL WATERS BEFORE SUNRISE TUE AS A SURFACE HIGH SHIFTS OVER NW PORTION SURROUNDED BY LIGHT AND VARIABLE WINDS. THIS SURFACE HIGH WILL SHIFT RAPIDLY SE TO NEAR TAMPA BAY AT MIDDAY WED WITH A RIDGE EXTENDING W TO THE TX COASTAL BEND...AND CHANGE LITTLE THROUGH EARLY IN THE WEEKEND. THE ASSOCIATED SLY RETURN FLOW WILL INCREASE TO 20 KT OVER THE WESTERN GULF TUE EVENING AND GRADUALLY SPREAD E ACROSS ALL WATERS W OF 90W WED NIGHT. LATEST GUIDANCE HAS BACKED OFF ON STRENGTH OF THIS SLY FLOW...WITH ONLY BRIEF SURGES TO 25 KT THROUGH SAT...AND SEAS BUILDING TO ONLY 9 FT OVER THE FAR NW PORTION IN THE SE SWELL ON FRI AND SAT. SW NORTH ATLC S OF 31N W OF 65W... THE INITIAL COLD FRONT IS CURRENTLY APPROACHING BERMUDA AND HAS A SIGNIFICANT WIND SHIFT OVER E CUBA...AND IS STILL CONVECTIVE PER LIGHTNING DATA OVER THE CENTRAL WATERS...THUS WILL MAINTAIN BOUNDARY BUT SHOW TRANSITION TO A FRONTAL TROUGH. A SECONDARY SURGE...ALSO ANALYZED AS A COLD FRONT...IS RAPIDLY CATCHING UP WITH THE INITIAL BOUNDARY AND IS IDENTIFIED BY BKN-LOCALLY OVC LOW-MID CLOUDS EXTENDING SW ACROSS THE NW BAHAMAS TO THE N COAST OF CUBA. A THIRD BOUNDARY WILL ALSO SWEEP E ACROSS THE NORTHERN WATERS...ALL ENDING WITH A SINGLE FRONTAL TROUGH EXTENDING FROM JUST E OF BERMUDA TO HISPANIOLA ON WED...WITH WINDS ENHANCED TO 20 KT BOTH E AND W OF THE TROUGH...BUT ONLY ALONG THE NORTHERN SEGMENT. A SURFACE HIGH WILL SHIFT E ACROSS THE GULF OF MEXICO EARLY IN THE WEEK...AND WILL CROSS CENTRAL FL ON WED...INTO THE ATLC ALONG 28N WED NIGHT...DROPPING THE LOW WINDS TO VARIABLE AT 5-10 KT OVER THE CENTRAL WATERS. THE SURFACE HIGH WILL THEN TURN NE AND RACE SE OF BERMUDA ON THU NIGHT LEAVING A RIDGE SW TO CENTRAL FL EARLY FRI. THE RIDGE WILL SHIFT N FRI NIGHT AND SAT. A SWATH OF NE WINDS AT 20 KT WILL CONTINUE ACROSS THE SOUTHERN WATERS THROUGH FRI NIGHT JUST TO W OF THE WESTWARD DRIFTING FRONTAL TROUGH REMNANTS. SW-W WINDS WELL N OF THE RIDGE...ALONG 31N...WILL PULSE AT 15-20 KT WED-SAT AS A SERIES OF TROUGHS...OR WEAK COLD FRONTS...PASS E ACROSS THE EXTREME NORTHERN WATERS WELL N OF THE RIDGE AXIS. CARIBBEAN SEA... A COLD FRONT WELL DEFINED IN THIS MORNINGS E CUBAN OBSERVATION DATA EXTENDS SW ACROSS THE NW CARIBBEAN...WITH ITS SOUTHERN SEGMENT SLIGHTLY DIFFICULT TO ACCURATELY LOCATE. BUT UNSEASONABLE N WINDS DOMINATE THE CARIBBEAN W OF 80W. SEAS ARE MAXING AT 9 FT ACROSS THE NORTHERN PORTION OF THE YUCATAN PASSAGE...AND WILL LIKELY BUILD TO 8 FT ALONG THE N COAST OF NICARAGUA IN THE SOUTHERLY CARIBBEAN CURRENT...BUT REMAIN LESS THAN 8 FT WHERE THE N FLOW IS IN PHASE WITH THE COLOMBIA-PANAMA GYRE. THESE POST FRONTAL WINDS WILL CLOCK TO THE NE THROUGH TUE AND DIMINISH SOMEWHAT. THE GRADIENT WILL TIGHTEN AGAIN ON WED AS THE FRONTAL REMNANTS SHIFT W ACROSS THE THE NW PORTION AND ATLC HIGH PRESSURE BUILDS WESTWARD. ELY WINDS WILL REMAIN AT 15 KT OVER THE E AND CENTRAL CARIBBEAN WATERS WITH SEAS TO MAX AT 6 FT IN E SWELL THROUGH WED...THEN INCREASE WED NIGHT THROUGH SAT. TROPICAL N ATLC S OF 19N W OF 55W... E-SE TRADES WILL CONTINUE AT 10-15 KT WITH SEAS IN THE 4-6 FT RANGE IN NE-E SWELL THROUGH EARLY FRI...THEN INCREASE TO 15-20 KT FRI NIGHT AND SAT. 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 NELSON