000 AGXX40 KNHC 200754 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 250 AM EDT FRI APR 20 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... IN THE SHORT TERM...WEAK HIGH PRES OF 1015 MB IS ANALYZED IN THE FAR N CENTRAL GULF NEAR 29N91W. A 101 MB LOW IS OVER THE FLORIDA PANHANDLE WITH A WEAKENING STATIONARY FRONT EXTENDING FROM IT SE TO OVER CENTRAL FLORIDA. A SURFACE TROUGH SHOWS UP WELL ON SHORTWAVE IR IMAGERY OVER THE SE PART OF THE GULF FROM NEAR 27N83W TO INLAND THE NE YUCATAN PENINSULA. BUOY OBSERVATIONS IN THE ERN GULF PICK UP ON THE NE TO SE WIND SHIFT ACROSS THE TROUGH. CURRENT WIND AND SEA CONDITIONS THROUGHOUT ARE RATHER ON THE LIGHT SIDE...EXCEPT IN THE FAR WRN PORTION OF THE GULF FROM 25N TO 28N W OF 95W WHERE SE WINDS WINDS HAVE INCREASED TO 15-20 KT. IN THE UPPER LEVELS...A SHORTWAVE TROUGH HAS JUST MOVED E OF FLORIDA INTO THE WRN ATLC LEAVING BEHIND RATHER ZONAL FLOW ALOFT. HOWEVER...THE ZONAL FLOW AND RATHER BENIGN SURFACE CONDITIONS WILL QUICKLY CHANGE IN THE MEDIUM TO LONG TERM DUE TO A VIGOROUS UPPER LEVEL TROUGH CURRENTLY DIPPING SWD ACROSS THE CENTRAL AND SRN PLAINS. THIS FEATURE IS ACCOMPANIED BY A SURFACE COLD FRONT THAT WILL RAPIDLY SWEEP SEWD ACROSS TEXAS AND INTO THE WRN GULF WATERS FRI NIGHT. THE UPPER LEVEL DYNAMICS ASSOCIATED WITH THIS FEATURE WILL BECOME ROBUST ENOUGH TO SPIN OFF A SURFACE LOW ALONG THE COLD FRONT NEAR 28N89W BY EARLY SAT WITH THE COLD FRONT EXTENDING FROM THE LOW SW TO NEAR THE NW YUCATAN PENINSULA. THE LOW WILL THEN MOVE TO NEAR 28N85W BY EARLY SAT EVENING WITH THE COLD FRONT TO THE NE YUCATAN PENINSULA. THE LOW WILL THEN TRACK ENE ACROSS N FLORIDA SAT NIGHT AND SUN PUSHING THE COLD FRONT TO SE OF THE AREA SUN AFTERNOON AS THE LOW TRACKS NE TO OFFSHORE THE SE U.S. MODELS SUGGEST THAT THE FRONT WILL MOST LIKELY BE PRECEDED BY DEEP CONVECTION. A SQUALL LINE WILL MOST LIKELY DEVELOP OUT AHEAD OF IT WITH TSTMS VERY CAPABLE OF PRODUCING VERY HAZARDOUS MARINE CONDITIONS. IN ADDITION...NLY WINDS OF 25-30 KT ARE FORECAST BEHIND THE FRONT WITH SOME POSSIBLE INSTANCES OF GUSTS TO GALE FORECAST ALONG PORTIONS OF THE WRN GULF FRI NIGHT INTO SAT. SEAS WILL BUILD TO LARGE VALUES 11 OR 12 FT IN THE ERN GULF BY SUN. CONDITIONS THEN SUBSIDE LATE SUN THROUGH EARLY NEXT WEEK AS WEAK HIGH PRES SETTLES IN OVER THE AREA. SW NORTH ATLC S OF 31N W OF 65W... HIGH PRES OF 1018 MB IS CENTERED NE OF THE BAHAMAS AT 28N70W WITH A RIDGE SW TO THE STRAITS OF FLORIDA. THE PRES GRADIENT ON THE SRN PERIPHERY OF THE RIDGE IS MAINTAINING LIGHT TO MODERATE NE WINDS OVER THE SRN PORTION. SCATTERED SHOWERS AND TSTMS ARE THAT EARLIER WHERE OVER THE NW WATERS HAVE SINCE DIMINISHED. CHANGES ARE IN STORE FOR THE AREA IN NEAR FUTURE AS THE GULF OF MEXICO STORM SYSTEM DESCRIBED ABOVE MIGRATES EWD THROUGH THE UPCOMING WEEKEND. THE RESULTING TIGHT PRES GRADIENT AHEAD OF THE LOW AND COLD FRONT WILL BRING A SUBSTANTIAL INCREASE TO SLY WINDS N OF THE BAHAMAS BEGINNING TONIGHT AND PROGRESSIVELY SPREAD EWD THROUGH SUN. THESE WINDS ARE FORECAST TO REACH 30 KT IN THE NRN PORTION OF THE AREA...BUT MAY EASILY ATTAIN GUSTS TO GALE FORCE. RIGHT NOW...IT APPEARS THAT IF GUSTS TO GALE FORCE OCCUR THEY SHOULD NOT BE FREQUENT AS FORECAST JUST N OF THE WATERS. THE COLD FRONT WILL MOVE ACROSS THE NW WATERS SAT NIGHT AS THE ATTENDANT LOW TRACKS NE ALONG OR JUST OFFSHORE THE SE U.S. COAST WHILE DEEPENING. BY LATE SUN AFTERNOON...THE COLD FRONT WILL REACH FROM NEAR 30N78W TO W/CENTRAL CUBA...FROM NEAR 30N75W TO ERN CUBA BY EARLY MON...AND BEGIN TO WEAKEN AS IT REACHES A PSN FROM NEAR 30N68W TO WINDWARD PASSAGE BY TUE AFTERNOON. WINDS AND SEAS DIMINISH OVER THE AREA BEHIND THE FRONT AS HIGH PRES BUILDS IN OVER THE WATERS. CARIBBEAN SEA... WINDS REMAIN RATHER LIGHT ACROSS THE AREA...WITH NE-E WINDS OF 15 KT OVER THE ERN AND CENTRAL ZONES AND SE WINDS OF 10 KT IN THE WRN PORTION. MAX SEAS ARE 7 FT IN THE SW PART OF THE CARIBBEAN. SEAS WILL CONTINUE TO SUBSIDE THROUGH SUN UNDER THE LIGHT GRADIENT. THE SE WINDS IN THE WRN PORTION BEGIN TO VEER AROUND TO THE S AND SW ON SAT AS THE GULF OF MEXICO COLD FRONT APPROACHES THE NW PORTION. NWP MODELS SUGGEST THAT THE SOUTHERN PORTION OF THE FRONT WILL ENTER THE NW CARIBBEAN SAT AND SUN FOLLOWED BY 20 KT W-NW WINDS. THE FRONT WILL THEN WEAKEN AND GRADUALLY SLOW DOWN AS IT REACHES FROM CENTRAL CUBA TO GULF OF HONDURAS SUN...FROM ERN CUBA TO NE HONDURAS BY EARLY MON...AND FROM NEAR WINDWARD PASSAGE TO NEAR 14N82W BY TUE. 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 TUE. TROPICAL N ATLC S OF 19N W OF 55W... GENERALLY LIGHT E TRADES S OF 17N BECOME FRESH ON SAT AS HIGH PRES STRENGTHENS N OF AREA. NW-N WINDS OF 5-10 KT N OF 17N BECOME NE-E 10-15 KT LATER TODAY. SEAS WILL RANGE FROM 4-6 FT...WITH THE HIGHEST IN THE CENTRAL AND SRN PORTIONS. 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