000 AGXX40 KNHC 300734 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 234 AM EST WED DEC 30 2015 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...AND THE SW N ATLANTIC INCLUDING THE BAHAMAS. ...GULF OF MEXICO... MODEL PREFERENCE: BLEND OF GFS/NWPS WITH PREVIOUS FORECAST. HIGH CONFIDENCE THROUGH FRI THEN LOW CONFIDENCE OVER THE WEEKEND. THE WARM FRONT THAT HAS RAPIDLY PUSHED NORTHWESTWARD ACROSS THE GULF OVER THE PAST 24 HOURS IS EXPECTED TO SHIFT EASTWARD ACROSS THE NORTHERN GULF TODAY AND THU AS A WEAK SURGE OF COLDER AIR MOVES IN BEHIND THE FRONT. FRESH TO STRONG NE WINDS ARE EXPECTED IN THE NW GULF LATER TODAY. OBSERVATIONS OVER TEXAS WITHIN THIS COOLER AIRMASS DO NOT APPEAR TO BE DRAMATICALLY COLDER THAN THOSE TO THE EAST...SUGGESTING THE STRONG UKMET SOLUTION MAY BE OVERDONE. THE GFS IS STRONGER THAN THE ECMWF WITH THE WIND BEHIND THE FRONT IN THE WESTERN GULF TODAY AND THU. ITS COMPROMISE SOLUTION SEEMS REASONABLE. A STRONGER SURGE OF COLD AIR MOVES IN BEHIND THE FRONT LATE THU INTO THU EVENING. THE MODELS ARE IN REASONABLE AGREEMENT WITH THE FRONTAL POSITION THROUGH FRI NIGHT...WITH THE GFS HOLDING THE KINK IN THE FRONT OVER THE WESTERN GULF NEAR 24N AS OPPOSED TO NEAR 22N LIKE THE ECMWF/UKMET. THIS IS IN RESPONSE TO THE MORE AMPLIFIED MID-LEVEL RIDGE IN THE GFS OVER TEXAS AND THE W GULF FRI THROUGH EARLY SAT AHEAD OF ITS MORE AMPLIFIED SOUTHERN STREAM TROUGH. THE TREND IN THE MODELS IS TOWARD A SLOWER TROUGH HERE WHICH IS IN BEST AGREEMENT WITH THE GFS. THE GFS CARRIES GALES IN THE W CENTRAL GULF 18Z FRI THROUGH 18Z SAT AND IN THE SW GULF 06Z SAT THROUGH 18Z SAT. THE UKMET AND ECMWF SUGGEST NEAR GALE TO GALE CONDITIONS PERSISTING LONGER. THE GFS DEVELOPS WAVES ALONG THE FRONT IN ASSOCIATION WITH MID-LEVEL ENERGY RIDING THE SOUTHERN STREAM JET ON THE LEADING EDGE OF THE TROUGH BY LATE SAT. BOTH THE UKMET AND ECMWF HAVE TRENDED TOWARD MORE TROUGHING IN THE EASTERN GULF OVER THE WEEKEND DUE TO A WAVE ALONG THE SURFACE BOUNDARY. THIS GFS HOPPED ON THIS TREND EARLIER. THE GFS MAY HAVE SOME GRID-SCALE FEEDBACK ISSUES WHICH MAKE ITS SOLUTION LESS RELIABLE...BUT BLENDING IT WITH THE PREVIOUS FORECAST LESSENS THE NEGATIVE IMPACTS. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: BLEND OF GFS/NWPS GUIDANCE WITH PREVIOUS FORECAST. MEDIUM CONFIDENCE. THE 0254 UTC ASCAT-A PASS SHOWED 30-33 KT TRADE WINDS OFF THE NE COAST OF COLOMBIA. THE GFS SHOWS GALES HERE WHILE THE ECMWF AND UKMET DO NOT. IT GENERALLY PERFORMS BETTER UNDER STRONG TRADE WIND FLOW. THE RIDGE BUILDING BACK ACROSS THE SW N ATLC AND EASTERN GULF OF MEXICO HAS FORCED THE FRONT IN THE GULF NORTHWARD AS A WARM FRONT...BUT IT SHOULD SEE PULSES OF COLD AIR PUSH THE NORTHERN PORTION OF THE FRONT EASTWARD BEGINNING TODAY. GALE CONDITIONS SHOULD DIMINISH AFTER SUNRISE ON FRI AS THE LEADING EDGE OF THE GULF OF MEXICO COLD FRONT MOVES INTO THE SW N ATLC AND PUSHES THE RIDGE EASTWARD. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: BLEND OF GFS/NWPS GUIDANCE WITH PREVIOUS FORECAST. HIGH CONFIDENCE THROUGH FRI NIGHT AND LOW CONFIDENCE OVER THE WEEKEND. FRESH TO STRONG TRADE WINDS NEAR THE N COAST OF HISPANIOLA AND THE ATLC APPROACHES TO THE WINDWARD PASSAGE ARE THE RESULT OF THE PRESSURE GRADIENT BETWEEN SUBTROPICAL RIDGE STRETCHED FROM 31N65W TO DAYTONA BEACH AND LOWER PRESSURE OVER THE SOUTHERN CARIBBEAN. THIS GENERAL PATTERN IS EXPECTED TO PERSIST UNTIL EARLY FRI BEFORE DIMINISHING AS THE FRONT IN THE GULF OF MEXICO MOVES EASTWARD INTO THE NW PORTION OF THE ZONE...PUSHING THE SUBTROPICAL RIDGE EASTWARD. THE GFS IS PREFERRED WITH THE FRONTAL TIMING HERE. THE BIGGEST QUESTION MARK COMES OVER THE WEEKEND WHEN THE GFS DEVELOPS A STRONGER WAVE ALONG THE FRONT OVER THE BAHAMAS THAN THE GFS AND UKMET. THE GFS IS MORE CONSISTENT WITH THE FORECAST OF CARRYING A WAVE ALONG THE BOUNDARY AT THAT TIME THAN THE ECMWF AND UKMET RUNS. UNCERTAINTY COMES INTO PLAY WITH THE GRID-SCALE FEEDBACK SEEN IN THE GFS N OF THE BAHAMAS SUN. BLENDING THE 00Z GFS WITH THE PREVIOUS FORECAST HELPS LESSEN THE NEGATIVE IMPACTS OF THIS FEEDBACK. SEE THE GULF OF MEXICO SECTION FOR MORE DETAILS ON THE FORECAST FOR THIS FRONT. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... .GMZ017...W CENTRAL GULF FROM 22N TO 26N W OF 94W... GALE CONDITIONS POSSIBLE FRI NIGHT INTO SAT. .GMZ023...SW GULF S OF 22N W OF 94W... GALE CONDITIONS POSSIBLE FRI NIGHT INTO SAT. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... .AMZ031...CARIBBEAN FROM 11N TO 15N BETWEEN 72W AND 80W INCLUDING COLOMBIA BASIN... GALE WARNING EARLY TODAY INTO THU NIGHT. GALE CONDITIONS POSSIBLE THU NIGHT. .SW N ATLANTIC INCLUDING THE BAHAMAS... NONE. $$ *FOR DETAILED ZONE DESCRIPTIONS PLEASE VISIT: HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT: HTTP://WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP FOR ADDITIONAL INFORMATION PLEASE VISIT: HTTP://WWW.HURRICANE WARNINGS.GOV/MARINE $$ .FORECASTER SCHAUER. NATIONAL HURRICANE CENTER.