000 AGXX40 KNHC 060618 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 118 AM EST SAT DEC 6 2014 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: LATEST GFS BLENDED WITH PREVIOUS/OFFICIAL FORECAST. LATEST TAFB-NWPS USED TO ADJUST WAVE PARAMETERS. HIGH CONFIDENCE. WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW THE ADVISORY CRITERIA OF 20-25 KT AND 8 FT...RESPECTIVELY...THROUGH THE END OF THE FORECAST PERIOD ON WED NIGHT. TROUGHING OVER THE CENTRAL N ATLC HAS WEAKENED THE SUBTROPICAL RIDGE AND WEAKENED THE PRESSURE GRADIENT OVER THE GULF OF MEXICO. A WEAK COLD FRONT WILL MOVE INTO THE NW GULF SAT EVENING AND IS EXPECTED TO STRETCH FROM NAPLES FLORIDA TO BROWNSVILLE TEXAS SUN EVENING. THE FRONT WILL DISSIPATE OVER THE W GULF MON AS IT RETROGRADES NORTHWARD WHILE THE EASTERN PORTION PASSES THROUGH THE STRAITS OF FLORIDA AND DISSIPATES TUE. THE MODELS HAVE COME INTO BETTER AGREEMENT TODAY WITH THE STRENGTH AND TIMING OF THIS FRONT AND SHOW LOWERING THICKNESSES IN THE EASTERN GULF LATE TUE AND WED AS THE UPPER TROUGH AMPLIFIES OVER THE U.S. EAST COAST. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS/OFFICIAL FORECAST. LATEST TAFB-NWPS USED TO ADJUST WAVE PARAMETERS. HIGH CONFIDENCE. SHIP 9HA2583 HAS REPORTED 20-25 KT WINDS AND 9-11 FT SEAS IN THE ATLC APPROACH TO THE WINDWARD PASSAGE FROM 03Z-05Z. THIS IS CONSISTENT WITH EARLIER ASCAT PASSES OVER THE AREA. THE MODELS GENERALLY AGREE ON 25 KT WINDS IN THE WINDWARD PASSAGE. IT IS UNUSUAL FOR THE ECMWF AND UKMET TO BE THIS STRONG IN A NE FLOW REGIME HERE. CONFIDENCE IS HIGH IN FRESH TO STRONG WINDS PENETRATING FROM THE WINDWARD PASSAGE SOUTHWARD ALONG THE E COAST OF JAMAICA THROUGH LATE SAT. NONE OF THE MODELS HAD QUITE AS LARGE AN AREA OF FRESH TO STRONG NE WINDS AS THE 0258 UTC ASCAT-B PASS OVER THE AREA. THE GFS LOOKS ACCEPTABLE HERE...BUT WINDS WERE BUMPED UP. THE NWPS WAS SLIGHTLY HIGHER THAN THE MWW3 HERE AND WAS USED TO ADJUST THE WAVE FORECAST...WITH SEAS BUMPED UP FURTHER IN THE PASSAGE AND ATLC APPROACH. THE AFOREMENTIONED ASCAT PASS ALSO SHOWED 20-25 KT WINDS IN THE LEE OF CUBA. THE NAVGEM IS THE BEST INITIALIZED HERE WITH THE OTHER MODELS ON THE WEAK SIDE. THE GFS WAS GENERALLY GOOD...BUT WINDS WERE BUMPED UP YET AGAIN UNTIL SUN WHEN TROUGHING BUILDS N OF THE AREA AS A COLD FRONT FROM THE GULF APPROACHES THE REGION. THIS WEAK FRONT WILL DISSIPATE BEFORE MOVING INTO THE CARIBBEAN MON NIGHT. OTHERWISE...WINDS AND SEAS WILL REMAIN UNDER ADVISORY CRITERIA OVER THE ENTIRE AREA UNTIL WED WHEN 8-10 FT N SWELL IS EXPECTED TO SEEP INTO THE TROPICAL N ATLC WATERS. ...SW N ATLANTIC S OF 31N W OF 55W INCLUDING THE BAHAMAS... MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS/OFFICIAL FORECAST UNTIL MON THEN THE ECMWF ADDED TO THE BLEND. LATEST TAFB-NWPS AND MWW3 USED TO ADJUST WAVE PARAMETERS. MEDIUM CONFIDENCE. LOW PRES ALONG THE BROAD TROUGH CENTERED ALONG 50W WILL GRADUALLY DEEPEN AND MOVE N THROUGH SUN NIGHT. THE MODELS ARE IN REASONABLE AGREEMENT ON THIS FORECAST. DIFFERENCES COME INTO PLAY AS THE UPPER TROUGH SUPPORTING THIS SYSTEM BEGINS TO PHASE WITH A TROUGH APPROACHING FROM THE NW. THE GFS IS ON THE FAST END OF THE GUIDANCE TO SHIFT THE SURFACE LOW NORTHEASTWARD AND BRING THE COLD AIR IN BEHIND THE FRONT ASSOCIATED WITH THE NEW UPPER TROUGH SUN NIGHT AND MON. CONFIDENCE WANES FURTHER N MON NIGHT INTO TUE AS A NEW TROUGH AMPLIFIES OVER THE U.S. EAST COAST...SENDING THE AFOREMENTIONED PHASED TROUGH NEGATIVE TILT AND WEAKENING AS IT MOVES EASTWARD. THE GFS IS ON THE WEAK END OF THE GUIDANCE ENVELOPE WITH THE AMPLIFYING TROUGH AND ASSOCIATED LOW AND COLD FRONT OFF THE U.S. EAST COAST TUE AND WED. BLENDING THE GFS WITH THE 12Z/05 ECMWF BRINGS ITS SOLUTION CLOSER TO THE GLOBAL MODEL CONSENSUS AND THE 00Z GEFS MEAN FORECAST. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... NONE. $$ *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.