000 AGXX40 KNHC 060721 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 321 AM EDT WED MAY 6 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. MODEL PREFERENCE: 00 UTC GFS BLENDED WITH PREVIOUS/OFFICIAL FORECAST. 00 UTC TAFB NWPS FOR WAVE PARAMETERS. HIGH CONFIDENCE. ...GULF OF MEXICO... AN UPPER TROUGH REACHES FROM THE NE GULF INTO THE NW CARIBBEAN. THIS CONTINUES TO ENHANCE SHOWERS AND THUNDERSTORMS OVER THE STRAITS OF FLORIDA...BUT FAIRLY DRY AIR IS IN PLACE ON THE WESTERN SIDE OF THE TROUGH OVER THE REMAINDER OF THE GULF. MODERATE TO OCCASIONALLY FRESH E TO SE WINDS ARE NOTED AT THE SURFACE ACROSS THE GULF SOUTH OF HIGH PRES OFF THE CAROLINA COAST. SEAS ARE GENERALLY 3 TO 5 FT IN THE EASTERN GULF AND 5 TO 7 FT OVER THE WESTERN GULF. LITTLE CHANGE IS EXPECTED THROUGH THE WEEKEND...WITH THE HIGH PRES BUILDING OVER THE NE GULF ALLOWING WINDS AND SEAS TO DIMINISH FURTHER IN THE EASTERN GULF. WINDS WILL PULSE TO 20 KT ALONG AND OFFSHORE OF THE NW PORTION OF THE YUCATAN PENINSULA DURING THE OVERNIGHT HOURS THROUGH THE FORECAST PERIOD. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: 00 UTC GFS BLENDED WITH PREVIOUS/OFFICIAL FORECAST. 00 UTC TAFB NWPS FOR WAVE PARAMETERS. HIGH CONFIDENCE. CLUSTERS OF THUNDERSTORMS PERSIST FROM GRAND CAYMAN THROUGH CENTRAL CUBA ASSOCIATED WITH AN UPPER TROUGH THAT CONTINUES TO EXTEND FROM THE NE GULF OF MEXICO THROUGH THE SW CARIBBEAN. THIS WILL DIMINISH THROUGH TONIGHT AS THE TROUGH AXIS SHIFTS SLIGHTLY EAST AND DEEP LAYER MOISTURE LESSENS. ELSEWHERE A TIGHT PRESSURE GRADIENT IS IN PLACE ACROSS THE SOUTH CENTRAL CARIBBEAN BETWEEN A SUBTROPICAL RIDGE AND COMPARATIVELY LOWER SURFACE PRESSURE ALONG NORTHWESTERN COLOMBIA. THIS PATTERN IS SUPPORTING FRESH TO STRONG NE TO E WINDS ALONG THE NORTHERN COASTS OF COLOMBIA AND VENEZUELA. A RECENT ASCAT SATELLITE PASS REVEALED 25 TO 30 KT WINDS OFF NE COLOMBIA. THE RESULTANT SEAS ARE 8 TO 12 FT ACCORDING TO A RECENT ALTIMETER SATELLITE PASS AND BUOY OBSERVATIONS. THE FORECAST CONTINUES TO CALL FOR THIS AREA OF FRESH TO STRONG TRADES TO PERSIST ACROSS THE CENTRAL CARIBBEAN THROUGH FRI WITH SEAS BUILDING TO 10 TO 13 FT AS THE SUBTROPICAL RIDGE BUILDS TO THE NORTHEAST. MODERATE TO FRESH TRADES WILL PERSIST ACROSS THE TROPICAL N ATLC WITH SEAS 5 TO 8 FT. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: BLEND OF 00 UTC GFS WITH 12 UTC ECMWF. MEDIUM CONFIDENCE THROUGH TONIGHT THEN HIGH CONFIDENCE. THERE IS MORE AGREEMENT AMONG MAJOR MODELS WITH REGARD TO DEVELOPING LOW PRES OVER THE BAHAMAS...BUT MINOR DIFFERENCES REMAIN. OBSERVATIONS FROM SOUTH FLORIDA AND THE BAHAMAS ALONG WITH SOUTH FLORIDA RADAR DISPLAYS INDICATE AN AREA OF LOW PRES BETWEEN WEST PALM BEACH AND GRAND BAHAMA ISLAND. IN ADDITION...EARLIER ASCAT SATELLITE IMAGERY INDICATED A SHARP TROUGH NE OF ABACO. THE LATEST GFS INITIALIZES WELL WITH BOTH THESE FEATURES...AND INDICATES THEY WILL MOVE TOGETHER IN A COMPLEX DUMBBELL PATTERN THROUGH LATE TODAY...EVENTUALLY COMING TOGETHER TONIGHT AS AN ELONGATED LOW CENTERED NEAR 31N78W. THE LATEST ECMWF INDICATES A SIMILAR PATTERN...BUT FAVORS THE NORTHERN ROTATION AS DOMINANT AND SHOWS A MORE ORGANIZED LOW A LITTLE TO THE SOUTHEAST OF THE GFS POSITION IN 24 HOURS WHICH IS ACTUAL MORE IN LINE WITH THE GFS ENSEMBLE. THE UKMET REMAINS SOMEWHAT OF AN OUTLIER...WITH A DEEPER LOW MORE TO THE NORTHEAST IN 24 HOURS. THE CLOSE PROXIMITY OF THE GFS AND EC FORECAST POSITION RAISE FORECAST CONFIDENCE AND POINT TO A SLOW DEVELOPMENT THROUGH TODAY WITH A DRIFT TO THE NORTH. THIS IS CORROBORATED BY GOOD AGREEMENT AMONG NHC BAM GUIDANCE. GIVEN THE INDICATIONS OFF SE FLORIDA OF THE SOUTHERN CIRCULATION...THE GFS MAY BE MORE CORRECT SHOWING A COMPLEX AND ELONGATED LOW. THE MAIN IMPACT WILL BE ROUGHLY THE SAME FOR MARINE INTERESTS...20 TO 30 KT WINDS WITH SEAS 8 TO 12 FT WITHIN 180 NM OF THE CENTER MAINLY OVER THE NORTHERN SEMICIRCLE. THUNDERSTORMS WILL PERSIST ACROSS THE AREA FROM CENTRAL CUBA TO NE OF THE BAHAMAS...GRADUALLY DIMINISHING FROM SOUTH TO NORTH THROUGH TONIGHT. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... NONE. $$ *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 CHRISTENSEN. NATIONAL HURRICANE CENTER.