000 AGXX40 KNHC 221756 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 155 PM EDT SUN APR 22 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 SURFACE LOW IS OVER NE FL ATTM AND LIFTING RAPIDLY NE WITH A SERIES OF BOUNDARIES ROTATING SE ACROSS THE GULF WATERS. THE FIRST BOUNDARY...ANALYZED AS THE COLD FRONT...WILL MOVE THROUGH THE FL STRAITS AROUND SUNSET TODAY. A SECOND REINFORCING BOUNDARY...ANALYZED AS A TROUGH...WILL SWEEP SE THROUGH THE EASTERN WATERS TONIGHT. AT LEAST 2 MORE REINFORCING BOUNDARIES WILL RACE S ACROSS THE GULF TONIGHT AND EARLY MON MAINTAINING NW-N 20-25 KT WINDS WHICH WILL DIMINISH FROM NW TO SE AND FINALLY BELOW 20 KT ALL WATERS LATE MON NIGHT. BY THEN A WEAK RIDGE WILL SHIFT SE OVER THE NW COASTAL PLAINS WITH THE LOW LEVEL WINDS DIMINISHING TO LIGHT AND VARIABLE OVER THE EXTREME NW PORTION. THE ASSOCIATED SURFACE HIGH WILL SHIFT RAPIDLY SE TO OVER THE N CENTRAL WATERS TUE NIGHT...AND REACH NEAR TAMPA BAY BY MIDDAY WED WITH A RIDGE EXTENDING W TO THE TX COASTAL BEND. GUIDANCE IS SUGGESTING THE ASSOCIATED SLY RETURN FLOW WILL INCREASE TO 20 KT OVER THE WESTERN GULF AS EARLY AS TUE NIGHT AND INCREASE TO 20-25 KT ALL WATERS W OF 90W BY LATE WED NIGHT AND CONTINUE THROUGH THU NIGHT...AND GRADUALLY INCREASE TO 20 KT IN E-SE FLOW ALL WATERS E OF 90W ON FRI. SW NORTH ATLC S OF 31N W OF 65W... THE COLD FRONT HAS MOVED OVER THE EXTREME NW WATERS WITH A SURFACE LOW RACING NE ALONG THE FRONTAL BOUNDARY. THIS WILL ACCELERATE THE COLD FRONT EASTWARD TONIGHT BUT PRECEDED BY A PRE-FRONTAL TROUGH WHERE THE MAJOR WIND SHIFT FROM S-SW WILL OCCUR. THE FRONT WILL REACH 31N74W TO CUBA AT 22N78W AT SUNRISE MON...FROM 31N67W TO WINDWARD PASSAGE AT SUNRISE TUE AND FROM 31N62W TO HISPANIOLA AT SUNRISE WED. THE N SEGMENT WILL CONTINUE E TO ALONG 31N59W TO 25N64W AT SUNRISE THU AND ALONG 31N57W TO 26N63W AT SUNRISE FRI. THE SOUTHERN SEGMENT STALLS THU AND WEAKENS AS THE REMNANTS DRIFT W BETWEEN HISPANIOLA AND CUBA THROUGH FRI. SOUTHERLY WINDS JUST AHEAD OF THE PREFRONTAL TROUGH WILL MAX AT 30 KT THROUGH TONIGHT WHILE 20-25 KT ELSEWHERE AS FAR S AS 22N. EXPECT THE POST FRONTAL WINDS TO MAX AT 30 KT EVEN AS FAR S AS THE FL STRAITS TODAY...BUT MAX AT 30 KT ONLY OVER THE NW WATERS BRIEFLY LATE TONIGHT. A SERIES OF SECONDARY TROUGHS WILL SWEEP E ACROSS THE NORTHERN WATERS MAINTAINING W-NW WINDS AT 20 KT THROUGH EARLY WED. A SURFACE HIGH WILL SHIFTING E ACROSS THE GULF OF MEXICO EARLY IN THE WEEK WILL CROSS CENTRAL FL ON WED INTO THE ATLC ALONG 28N WED NIGHT DROPING THE LOW WINDS TO 5-10 KT OVER THE AREA N OF 25N W OF 77W. THE SURFACE HIGH WILL THEN TURN NE AND RACE SE OF BERMUDA ON THU NIGHT LEAVING A RIDGE SW TO CENTRAL FL EARLY FRI...AND TO NE FL ON FRI NIGHT. A SWATH OF NE WINDS AT 20 KT WILL CONTINUE ACROSS THE SOUTHERN WATERS THROUGH FRI JUST TO W OF THE FRONTAL TROUGH. SW WINDS WELL N OF THE RIDGE...ALONG 31N...WILL INCREASE TO 15 PERHAPS 20 KT FRI NIGHT. CARIBBEAN SEA... A PREFRONTAL TROUGH PRECEDES A COLD FRONT ADVANCING THROUGH THE NW WATERS WITH THE MAJOR WIND SHIFT AND CONVECTION OCCURRING ALONG THE TROUGH. ALTHOUGH A SHIP REPORTED 30 KT IN THE WINDWARD PASSAGE EARLIER...EXPECT WINDS TO NOW MAX AT 25 KT EVERYWHERE W OF TROUGH. ALSO SLY FLOW E OF TROUGH HAS DIMINISHED BELOW 20 KT THUS DROPPED MENTION IN THIS MORNINGS PACKAGE. EXPECT FRONT TO MERGE WITH TROUGH FROM 22N78W TO 15N82W MON MORNING AND WEAKEN TO A FRONTAL TROUGH FROM 20N74W TO 14N80W TUE MORNING. BY THEN NLY WINDS WILL HAVE DIMINISHED TO 15-20 KT OVER NW CARIBBEAN AND ALONG THE COAST OF NICARAGUA. ELY WINDS WILL REMAIN AT 15 KT OVER THE E AND CENTRAL CARIBBEAN WATERS WITH SEAS TO MAX AT 6 FT IN E SWELL MAINLY ACROSS THE CENTRAL WATERS. TROPICAL N ATLC S OF 19N W OF 55W... SE-E TRADES AT 10-15 KT WITH SEAS IN THE 4-6 FT RANGE IN NE-E SWELL THROUGH THE PERIOD. 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