000 AGXX40 KNHC 310717 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 217 AM EST THU DEC 31 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 NIGHT...THEN MEDIUM CONFIDENCE SAT THROUGH MON NIGHT. THE 0418Z ASCAT PASS SHOWED 25 KT N-NW WINDS ALONG THE MEXICAN COAST NEAR TAMPICO. BOTH THE 00Z GFS AND ECMWF HAVE WINDS IN THE 20-25 KT RANGE HERE...BUT THE CURRENT FORECAST GRIDS WILL NEED TO BE BUMPED UP TO MATCH THE OBSERVATIONS INITIALLY. A STRONGER SURGE OF COLD AIR MOVES IN BEHIND THE FRONT LATER TODAY AND TONIGHT. THE MODELS ARE IN EXCELLENT 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. GALES IN THE W CENTRAL GULF PERSIST FROM 18Z FRI UNTIL 18Z SAT IN THE GFS AND FROM 18Z FRI UNTIL 12Z SAT IN THE UKMET WHILE THE ECMWF DOES NOT SHOW GALES HERE. OVER THE CONUS...THE MODELS HAVE GENERALLY NOT BEEN AS COLD AS THE OBSERVATIONS WITH THIS AIR MASS. THE STRONGER SOLUTIONS SEEM MORE REASONABLE. PREFER TO LEAN TOWARD THE GFS AND UKMET...SHOWING A GALE FROM 18Z FRI UNTIL 15Z SAT. CONFIDENCE IN THE FORECAST WANES BY THE WEEKEND WHEN A SOUTHERN STREAM TROUGH BECOMES THE DOMINANT FORECAST FEATURE. THE MODELS HAVE TRENDED MORE AMPLIFIED OVER THE LAST FEW DAYS WORTH OF RUNS. THE GFS CONTINUES TO BE THE STRONGER SOLUTION. IT DRAGS A STRONGER FRONTAL WAVE THROUGH THE SOUTHERN GULF...REACHING S FLORIDA AROUND 06Z MON. THE ECMWF AND UKMET AGREE ON THIS TIMING...BUT ARE NOT AS STRONG. KEEPING WITH THE TREND...WILL ADJUST THE FORECAST TOWARD THE LATEST GFS. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: BLEND OF GFS/NWPS GUIDANCE WITH PREVIOUS FORECAST. HIGH CONFIDENCE THROUGH SUN...THEN MEDIUM CONFIDENCE. THE 0234 UTC ASCAT-A PASS SHOWED 30-33 KT TRADE WINDS OFF THE NE COAST OF COLOMBIA TO 14N. NONE OF THE MODELS SHOW THIS LARGE AN AREA OF NEAR GALE FORCE WINDS...BUT THE GFS IS THE CLOSEST. ASCAT-A GENERALLY UNDER-FORECASTS WINDS AT THIS SPEED...SO THE GALE WARNING REMAINS UP. ADJUSTMENTS WILL BE MADE TOWARD A STRONGER SOLUTION IN THE FORECAST GRIDS INITIALLY. THE GALE IS FORECAST TO END 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. THIS DIMINISHES WINDS AND SEAS ACROSS THE ENTIRE CARIBBEAN. MORE UNCERTAINTY COMES INTO PLAY BY MON AS THE COLD FRONT MOVES INTO THE NW CARIBBEAN. THE GFS IS FASTER TO MOVE THE FRONT INTO THE AREA. ITS SOLUTION IS PREFERRED OVER THE GULF OF MEXICO...AND IT WILL BE USED HERE TO ADJUST THE GRIDS. SEE THE GULF OF MEXICO SECTION FOR DETAILS. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: BLEND OF GFS/NWPS GUIDANCE WITH PREVIOUS FORECAST. MEDIUM CONFIDENCE. 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. THE MODELS ARE UNDER-FORECASTING THE WINDS HERE AND JUST NE OF THE CARIBBEAN WHERE SCATTEROMETER AND SURFACE OBSERVATIONS SHOW A SIZABLE AREA OF 20-25 KT WINDS. ADJUSTMENTS WILL BE MADE TO THIS ARE INITIALLY IN THE GRIDS. 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 SUN AND MON WHEN THE GFS DEVELOPS A STRONGER WAVE ALONG THE FRONT OVER THE BAHAMAS THAN THE ECMWF AND UKMET. THE ECMWF AND UKMET HAVE BEEN TRENDING STRONGER LIKE THE GFS. UNCERTAINTY COMES INTO PLAY WITH THE GRID-SCALE FEEDBACK SEEN IN THE GFS N OF THE BAHAMAS SUN NIGHT AND MON. 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. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... .GMZ017...W CENTRAL GULF FROM 22N TO 26N W OF 94W... GALE WARNING FRI INTO FRI NIGHT. GALE CONDITIONS POSSIBLE FRI NIGHT. .GMZ023...SW GULF S OF 22N W OF 94W... GALE WARNING FRI NIGHT. GALE CONDITIONS POSSIBLE FRI NIGHT INTO SAT NIGHT. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... .AMZ031...CARIBBEAN FROM 11N TO 15N BETWEEN 72W AND 80W INCLUDING COLOMBIA BASIN... GALE WARNING EARLY TODAY INTO FRI. .SW N ATLANTIC INCLUDING THE BAHAMAS... NONE. $$ *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.