000 AGXX40 KNHC 190714 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 315 AM EDT TUE APR 19 2011 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. SOUTHWEST N ATLC W OF 55W... THE MODELS CONTINUE TO BE IN REASONABLE AGREEMENT WITH THE EVOLUTION OF THE UPPER LOW CURRENTLY OVER THE WESTERN PORTION OF THIS AREA. THE WEAKENED LOW ALOFT IS EXPECTED TO ACQUIRE A NEW BATCH OF VORTICITY INTO ITS WESTERN SIDE FROM THE UPPER TROUGH PASSING TO ITS NE. WHAT IS LEFT OF THE LOW WILL STRENGTHEN AS IT RETROGRADES W WED AND THU BEFORE BEING NUDGED EASTWARD BY ANOTHER DEEP LAYER TROUGH FRI AND SAT. THE LATEST 00Z MODEL RUNS ARE TRENDING TOWARD ALLOWING MORE OF THIS ENERGY TO RESIST THE UPPER TROUGH LATE IN THE PERIOD AND LINGER JUST E OF THE BAHAMAS. AT THE SURFACE...ALL OF THE MODELS AGREE ON CARRYING A DISTINCT SURFACE LOW NEAR 25N TO THE N OF PUERTO RICO BY WED NIGHT. AT THE SAME TIME...A COLD FRONT MOVING THROUGH THE FAR N ATLC WED WILL PUSH THE SUBTROPICAL HIGH SOUTHWARD TOWARD THE LOW...INCREASING THE PRES GRADIENT AND SUGGESTING STRONG WINDS ON THE N SIDE OF THE SYSTEM. A GALE WARNING WILL BE ISSUED IN THE NEXT PACKAGE FOR LATE WED JUST E OF THE SW N ATLC OFFSHORE ZONE AS A RESULT. THE 12 HOUR TREND IN THE GFS...UKMET...AND ECMWF IS FOR A MORE WESTERN LOW TRACK...WITH MOST OF THE MODELS CARRYING THE SYSTEM INTO THE SW N ATLC ZONE AROUND THU. THE GFS CONTINUES TO BE THE SLOWEST SOLUTION WHILE ITS PARALLEL RUN IS LESS THAN A DEGREE FARTHER W AT THAT TIME. THE 00Z ECMWF APPEARS TO BE A COMPROMISE BETWEEN THE SLOWER GFS AND THE OTHER MODELS WHICH ARE FASTER. ITS FORECAST WILL BE USED AS THE PRIMARY GUIDANCE FOR THE UPDATED OFFSHORES. THERE IS SOME CONCERN THAT THE GALE TRIGGER MAY HAVE BEEN PULLED TOO QUICKLY AS THE 00Z ECMWF HAS TRENDED SLIGHTLY WEAKER THAN ITS 12Z RUN AND THE 00Z GEFS SHOWS NO CHANCE OF GALES...BUT THE OVERALL AGREEMENT IN THE MODELS FOR A STRONGER SOLUTION AND A TIGHT PRES GRADIENT...AT LEAST UNTIL FRI WHEN A PORTION OF THE UPPER SUPPORT LIFTS NE...SEEM TO WARRANT A WARNING. CARIBBEAN SEA AND TROPICAL ATLC W OF 55W... RELATIVELY LIGHT WINDS WILL PERSIST OVER THE MUCH OF CARIBBEAN AND TROPICAL N ATLC THROUGH SAT WITH THE SUBTROPICAL HIGH AND TRADE WINDS DISTURBED BY THE PERSISTENT DEEP LAYER TROUGHING OVER THE WESTERN PORTION OF THE SW N ATLC AREA. RETURN FLOW HAS INCREASED OVER THE FAR NW CARIBBEAN AS THE PRES GRADIENT STRENGTHENED BETWEEN HIGH PRES ACROSS THE SW N ATLC AND EASTERN GULF OF MEXICO AND INCREASED TROUGHING OVER THE SOUTHERN PLAINS AND NE MEXICO. THE GFS HOLDS ONTO 20 KT WINDS HERE INTO FRI AND SAT AFTER THE ECMWF HAS DIMINISHED THESE CONDITIONS. THE GFS APPEARS TO BE A FAST OUTLIER WITH THE DEEP LAYER TROUGHING OVER NORTH AMERICA AT THAT TIME...SO THE FORECAST WILL MORE CLOSELY FOLLOW THE ECMWF HERE. MEANWHILE...SHIPS 9HXD9 AND THE 0258 UTC ASCAT PASS SHOW WINDS TO 25 KT NEAR THE COAST OF COLOMBIA. THESE WINDS SHOULD CONTINUE CLOSE TO THE COAST THROUGH WED WHEN THE WEAKENED RIDGING TO THE NE DISRUPTS THE PRES GRADIENT HERE. WINDS ARE ALSO EXPECTED TO REMAIN AT 20 KT IN THE WINDWARD PASSAGE THROUGH SAT. GULF OF MEXICO... RIDGING IS BUILDING OVER THE EASTERN GULF AND LOW LEVEL TROUGHING IS BUILDING OVER THE PLAINS AND NE MEXICO...BUT NO COLD FRONTAL BOUNDARY IS EXPECTED TO MAKE IT AS FAR S AS THE GULF OF MEXICO THROUGH SAT. THE PERSISTENTLY STRONG PRES GRADIENT WILL KEEP FRESH TO OCCASIONALLY STRONG SE WINDS OVER THE MUCH OF THE WESTERN AND CENTRAL GULF TODAY THROUGH WED. THERE ARE NUMEROUS OBSERVATIONS IN THE 20 TO 25 KT RANGE IN THE WESTERN GULF AND THE 0302 UTC ASCAT PASS CONFIRM THESE CONDITIONS. THE AREA OF FRESH TRADE WINDS WILL SHRINK PRIMARILY TO THE WESTERN GULF WED NIGHT AND THU AS THE COLD FRONT MOVES INTO THE LOWER MISSISSIPPI VALLEY AND HIGH PRES PINCHES OFF AHEAD OF THE FRONT OVER THE NE GULF...DISTURBING THE E TO W PRES GRADIENT. BY FRI...THE FRONT WILL LIFT AWAY FROM THE AREA AND THE PRES GRADIENT WILL BE REINVIGORATED BY N TO S TROUGHING BUILDING OVER THE PLAINS. WARNINGS.. ATLC... .GALE WARNING FROM 25N TO 29N BETWEEN 58W AND 65W. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER