000 AGXX40 KNHC 170653 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 AM EDT SUN APR 17 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 ARE IN REASONABLE AGREEMENT WITH THE EVOLUTION OF THE UPPER LOW CURRENTLY OVER THE WESTERN PORTION OF THE AREA. THE LOW ALOFT IS EXPECTED TO WEAKEN MON AND TUE AS SOME OF THE VORT ENERGY ASSOCIATED WITH THE SYSTEM IS SIPHONED OFF TO THE E INTO ANOTHER DEEP LAYER LOW. AT THE SAME TIME...NEW ENERGY WILL BE DEPOSITED INTO THE WESTERN SIDE OF THE LOW BY AN UPPER TROUGH PASSING TO ITS N. WHAT IS LEFT OF THE LOW WILL RETROGRADE W WED AND THU BEFORE BEING NUDGED EASTWARD BY ANOTHER DEEP LAYER TROUGH FRI. THE 00Z ECMWF AND UKMET ARE SLIGHTLY DEEPER AT H5 WITH THIS LOW THAN THE GFS BY WED AND THU...BUT GFS HOLDS ONTO A STRONGER PRES GRADIENT AT THE SURFACE AND LARGER AREA OF FRESH WINDS OVER THE SW N ATLC OFFSHORE ZONE INTO THU THAN THE ECMWF. THE 06Z GEFS SHOWS LESS THAN A 10 PERCENT CHANCE OF WINDS OVER 20 KT BY SUNRISE THU...SO THE ECMWF WILL BE USED NEAR THE END OF THE FORECAST PERIOD. CARIBBEAN SEA AND TROPICAL ATLC W OF 55W... RELATIVELY LIGHT WINDS WILL PERSIST OVER THE CARIBBEAN AND TROPICAL N ATLC THROUGH MON WITH THE SUBTROPICAL HIGH AND TRADE WINDS DISTURBED BY PERSISTENT DEEP LAYER TROUGHING OVER THE WESTERN PORTION OF THE SW N ATLC AREA. BY TUE...RETURN FLOW IS EXPECTED TO INCREASE OVER THE NW CARIBBEAN AS DEEP LAYER AMPLIFIES OVER CENTRAL N AMERICA. THE GFS AND ECMWF ARE IN GOOD AGREEMENT ON BUMPING WINDS UP TO 20 KT IN THE GULF OF HONDURAS BY EARLY TUE CONTINUING THROUGH THE END OF THE PERIOD THU. MEANWHILE...THE 0200 UTC ASCAT PASS SHOWED WINDS TO 20 KT OFF THE COAST OF COLOMBIA. THESE WINDS SHOULD CONTINUE CLOSE TO THE COAST THROUGH WED MORNING...WITH THE MOST LIKELY TIME TO SEE FRESH WINDS BEING IN THE EARLY MORNING HOURS. GULF OF MEXICO... THE WEAKENING COLD FRONT STRETCHED FROM TAMPA BAY TO 23N89W WILL DISSIPATE TODAY. HIGH PRES BEHIND THIS FRONT WILL ANCHOR ITSELF E OF THE AREA THROUGH THU. DEEP LAYER TROUGHING WILL BUILD OVER THE PLAINS IN THE MEANTIME...BUT THE COLD FRONTAL BOUNDARY ASSOCIATED WITH THE NORTHERN STREAM TROUGHING IS NOT EXPECTED TO MAKE IT AS FAR S AS THE GULF OF MEXICO. THE PRES GRADIENT BETWEEN PERSISTENT RIDGING OVER THE EASTERN GULF AND TROUGHING OVER THE SOUTHERN U.S. PLAINS AND NE MEXICO WILL KEEP FRESH SE WINDS OVER THE MUCH OF THE WESTERN AND CENTRAL GULF MON THROUGH WED. THAT AREA WILL SHIFT PRIMARILY TO THE WESTERN GULF BY 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. THE 00Z ECMWF IS FASTER CARRYING THIS COLD FRONT SOUTHEASTWARD...BUT IT SEEMS TO MAKE LITTLE DIFFERENCE IN THE WIND FIELD OVER THE GULF. WARNINGS.. ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER