000 AGXX40 KNHC 210730 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 330 AM EST SUN MAR 21 2010 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W GULF OF MEXICO... THE 0000 UTC GEFS SHOWS OVER AN 80 PERCENT CHANCE OF GALES AS FAR E AS 87W OVER FAR N WATERS AT 1200 UTC THIS MORNING BEHIND THE COLD FRONT THAT IS CURRENTLY STRETCHED FROM NEW ORLEANS TO 19N96W. THE SREF ENSEMBLES ARE NOT AS BULLISH...SHOWING ONLY A 15 PERCENT CHANCE OF GALES BUT THEY EXTEND THE CHANCE OF GALES EASTWARD TO 86W. MOST BUOY OBSERVATIONS IN THE NW GULF OF MEXICO ZONE THIS MORNING SHOW NW WINDS IN THE 25-35 KT RANGE WHILE OBSERVATIONS IN THE MIDDLE GULF ZONE GENERALLY RANGE FROM 20-30 KT IN SE WINDS AHEAD OF THE FRONT. THE 25 KM ASCAT PASS SHOWS WINDS IN THE WESTERN GULF TO JUST BELOW GALE FORCE AT 0356 UTC. CONFIDENCE IS REASONABLY HIGH THAT THE GALE IS OCCURRING OVER W WATERS KNOWING THAT THE ASCAT RUNS LOW WITH WINDS THIS STRONG. THIS SYSTEM WILL INTENSIFY THIS MORNING AS IT TRAVELS THROUGH THE NORTHERN MIDDLE GULF WHEN THE SHORTWAVE ENERGY ALOFT CURRENTLY OVER EASTERN TEXAS SWEEPS INTO THE SE SIDE OF THE UPPER LOW...TURNING THE UPPER TROUGHING NEGATIVE TILT. THE SURFACE WINDS ARE FORECAST BY THE MODELS TO INTENSIFY AS A TRIPLE POINT LOW DEVELOPS ALONG THE COLD FRONT THIS MORNING WHEN THE SHORTWAVE ENERGY ALOFT PASSES SOUTH AND THEN SE OF THE UPPER LOW. WHILE THE 1200 UTC ECMWF AND 0000 UTC UKMET DO NOT BRING WINDS TO GALE FORCE...THEY HAVE A SOLID AREA OF 30 KT WINDS THROUGH THE NW AND NORTHERN MIDDLE GULF UNTIL SUNSET AS HIGH PRES MOVES INTO THE SW GULF WHILE LOW PRES IS MAINTAINED TO THE N ASSOCIATED WITH THIS SLOW MOVING SYSTEM. CONFIDENCE IS HIGH ENOUGH IN THIS SCENARIO THAT THE GALE WARNING WAS EXTENDED E TO 87W WHICH MOVES IT INTO THE MIDDLE GULF ZONE. WINDS ASSOCIATED WITH THIS FRONT ARE EXPECTED TO DIMINISH BELOW 20 KT IN THE MIDDLE AND EASTERN GULF OVERNIGHT MON NIGHT. HIGH PRESSURE WILL SHIFT E ACROSS THE NORTHERN GULF MON AND TUE WITH RETURN FLOW INCREASING AGAIN IN THE W GULF TUE AND WED. THE NEXT SOUTHERN STREAM SYSTEM WILL MOVE THROUGH TEXAS AND INTO THE NW GULF THU...BUT IT WILL NOT BE AS STRONG AS THE PREVIOUS SYSTEM AND GALES ARE NOT EXPECTED. TROPICAL ATLC AND CARIBBEAN SEA... A FRONTAL TROUGH STILL LINGERS FROM THE WINDWARD PASSAGE SW TO 17N80W WITH WINDS SE OF THE FRONT GENERALLY IN THE 20 TO 25 KT RANGE ACCORDING TO THE 0210 UTC ASCAT PASS AND SHIP ZCDF4 REPORTED 30 KT WINDS IN THE ATLC OPENING OF THE WINDWARD PASSAGE AT 0300 UTC. THE ENVISAT PASS FROM 0245 UTC SHOWED SEAS TO 12 FT IN THE CARIBBEAN S OF 15N AROUND 69W. THE CLOSEST SHIP IS C6KD8 AT 0600 UTC WHICH REPORTED 10 FT SEAS. BOTH THE ENVISAT PASS AND THIS SHIP ARE 2-4 FT BELOW THE MWW3 GUIDANCE DESPITE THE GFS DOING A REASONABLY GOOD JOB WITH THE WIND FIELD. ADJUSTMENTS WILL BE MADE TO THE SHORT TERM FORECAST ACCORDINGLY. SHOWERS INDUCED BY THIS LINGERING BOUNDARY SHOULD BEGIN TO LIFT N AND DISSIPATE TODAY IN ADVANCE OF THE NEXT SYSTEM. THE COLD FRONT IN THE GULF WILL PASS THROUGH THE YUCATAN CHANNEL BY EVENING BRINGING 20-25 KT N WINDS BEHIND IT OVERNIGHT MON NIGHT THROUGH TUE EVENING WHEN WINDS WILL BEGIN TO DIMINISH. THE FRONTAL BOUNDARY WILL DISSIPATE OVER THE NW CARIBBEAN BY THU WHEN RETURN FLOW TURNS WINDS MORE SOUTHEASTERLY AHEAD OF THE SYSTEM PASSING INTO THE NW GULF OF MEXICO. TRADE WINDS IN THE TROPICAL N ATLC ZONE WILL DIMINISH BELOW 20 KT WED AS THE COLD FRONT CURRENTLY OVER THE GULF OF MEXICO MOVES EASTWARD NORTH OF THE AREA...SHOVING THE SUBTROPICAL RIDGE AND THE STRONGEST PRES GRADIENT EASTWARD. SW N ATLC W OF 65W... THE PRES GRADIENT BETWEEN RIDGING FROM BERMUDA THROUGH THE CENTRAL BAHAMAS INTO CENTRAL CUBA AND THE COLD FRONT IN THE GULF OF MEXICO HAS BROUGHT E TO SE WINDS IN THE 20-30 KT RANGE TO WATERS W OF THE BAHAMAS S OF 26N THE PAST FEW HOURS. THE MODELS GENERALLY DO NO SHOW WINDS OVER 20 KT HERE...SO ADJUSTMENTS WERE MADE TO THE NOW-CAST AND SHORT RANGE FORECAST ACCORDINGLY. THE UKMET AND GFS WAIT TO RAISE WINDS TO 25 KT AS THEY SHIFT MORE SOUTHERLY LATER THIS MORNING AHEAD OF THE FRONT. THE WINDS SHOULD BE DIMINISHING PRIOR TO THE ARRIVAL OF THE COLD FRONT THIS EVENING. WITH THIS SYSTEM TURNING NEGATIVE TILT ALOFT AND LIFTING NE AS IT REACHES THE ATLC...EXPECT THE STRONGEST WINDS TO SHIFT NORTHWARD. GALES ARE NOT EXPECTED IN THE SW N ATLC WITH THIS SYSTEM. THE GFS TRIES TO DEVELOP A LOW PRES WAVE ALONG THE BOUNDARY N OF THE BAHAMAS THIS AFTERNOON. THE OTHER MODELS DO NOT SHOW A CLOSED CIRCULATION WITH THIS SYSTEM...BUT THE CONSENSUS IS THAT WINDS WILL REMAIN AT 20-30 KT AHEAD OF THE COLD FRONT AT LEAST N OF 28N AS IT TRAVERSES THE ZONE. HIGH PRES BUILDS BEHIND THE FRONT AND WINDS DIMINISH WED AND BECOME VARIABLE THU AS THE NW SWELL PUSHES E OUT OF THE AREA. WARNINGS... ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .GMZ080...GALE WARNING TODAY. .GMZ082...GALE WARNING TODAY. .GMZ084...GALE WARNING TODAY N OF 26N W OF 87W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER