000 AGXX40 KNHC 180643 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 AM EDT MON APR 18 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 TODAY 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. AT THE SURFACE...THERE IS INCREASING AGREEMENT FOR A DISTINCT SURFACE LOW TO LIE 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. WHILE THE 00Z GFS DOES SHOW WINDS BRIEFLY REACHING GALE FORCE...THE 00Z ECMWF DOES NOT DESPITE BEING STRONGER WITH THE DEEP LAYERED LOW. THE 00Z GEFS SHOW NO CHANCE OF GALE FORCE WINDS DEVELOPING OVER THE AREA THROUGH THE ENTIRE PERIOD. FOR NOW...A BLEND OF THE GFS AND ECMWF WILL BE USED FOR THE FORECAST. THIS CAPS WINDS AT 30 KT. CARIBBEAN SEA AND TROPICAL ATLC W OF 55W... RELATIVELY LIGHT WINDS WILL PERSIST OVER THE CARIBBEAN AND TROPICAL N ATLC THROUGH TODAY 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 IS EXPECTED TO INCREASE OVERNIGHT TONIGHT OVER THE NW CARIBBEAN AS THE PRES GRADIENT BUILDS 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 AND ECMWF ARE IN GOOD AGREEMENT ON BUMPING WINDS UP TO 20 KT IN THE GULF OF HONDURAS TONIGHT CONTINUING THROUGH THU. THE ECMWF BACKS OFF ON WINDS HERE FRI BECAUSE IT ALLOWS A STRONGER LOW MOVING THROUGH THE SW N ATLC TO DISRUPT THE RIDGE. MEANWHILE...SHIPS PINX...ELZL5...C6T2064...AND 9HXD9 ALL REPORTED WINDS AT OR ABOVE 20 KT OFF THE COAST OF COLOMBIA AT 0600 UTC. THESE WINDS SHOULD CONTINUE CLOSE TO THE COAST THROUGH WED WHEN THE WEAKENED RIDGING TO THE NE DISRUPTS THE PRES GRADIENT HERE. GULF OF MEXICO... 1017 MB HIGH PRES LIES OVER THE NE GULF OF MEXICO NEAR 29N86W AT 0000 UTC AND LOW LEVEL TROUGHING IS BUILDING OVER THE PLAINS...BUT NO COLD FRONTAL BOUNDARY IS EXPECTED TO MAKE IT AS FAR S AS THE GULF OF MEXICO THROUGH FRI. 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 TODAY THROUGH WED. SO FAR...IT IS PRIMARILY THE ELEVATED PLATFORM OBSERVATIONS THAT AREA REPORTING 20 KT OF WIND OR HIGHER. WINDS SHOULD INCREASE TO 20 KT AT 10 METERS ABOVE THE SURFACE LATER THIS MORNING. THE AREA OF FRESH TRADE WINDS WILL SHRINK PRIMARILY TO THE WESTERN GULF WED NIGHT THROUGH FRI 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. WARNINGS.. ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER