000 AGXX40 KNHC 111842 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 245 PM EDT FRI SEP 11 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO...STRONGEST WINDS CAN BE FOUND OVER THE NORTHERN GULF THIS AFTERNOON ON THE N SIDE OF A LOW PRESSURE TROUGH FROM SARASOTA...FL TO NEAR WESTERN CUBA THAT IS EATING INTO MEAN RIDGING OVER THE EASTERN GULF. WINDS TO 20 KT HAVE BEEN REPORTED GENERALLY N OF 28N AND E OF 90W OVER THE PAST FEW HOURS. SCATTERED MODERATE CONVECTION CAN BE FOUND OVER THE NORTH CENTRAL GULF IN THE MEAN...MOIST SOUTHERLY FLOW ON THE EASTERN SIDE OF A DEEPENING MID LEVEL LOW OVER TX. CONVECTIVE ACTIVITY IS EXPECTED IN THIS REGION THROUGH THE WEEKEND. THE MODELS AGREE ON LIFTING SOME OF THE MID LEVEL ENERGY ASSOCIATED WITH THE EASTERN GULF TROUGH THROUGH THE GULF OVER THE WEEKEND...STEERED NORTHWARD BY MEAN SOUTHERLY FLOW BETWEEN THE DEVELOPING DEEP-LAYERED LOW OVER TX AND THE RIDGING BUILDING INTO THE SE GULF. MEAN TROUGHING OVER THE NE GULF AND RIDGING OVER THE SE GULF SHOULD THEN PERSIST THROUGH TUE. HOWEVER...THE DEEP LAYERED LOW OVER TX SHOULD DRIFT NE EARLY NEXT WEEK AS A COLD FRONT MOVES IN AND THE UPPER LEVEL TROUGH SUPPORTING THE LOW TURNS NEGATIVE TILT. THIS WILL SHIFT THE PLENTIFUL SHOWER ACTIVITY EASTWARD IN THE NORTHERN GULF. THE CMC IS FASTER THAN THAN THE OTHER MODELS MOVING THE TX LOW NE INTO THE LOWER MISSISSIPPI VALLEY EARLY NEXT WEEK...SO ITS SOLUTION IS NOT PREFERRED. THE GFS AND ECMWF ARE IN REASONABLE AGREEMENT ON THE TIMING OF THE COLD FRONT SURGING S OF THE LOW INTO THE NW GULF ON MON/TUE...BUT THE GFS IS CONSIDERABLY FARTHER N WITH THE SURFACE LOW OVER E TX. A MODEL CONSENSUS REPRESENTED BY A BLEND OF THE ECMWF AND GFS WAS USED FOR THE FORECAST. SW N ATLC...A SURFACE TROUGH CAN BE FOUND THIS MORNING FROM NEAR 31N73W TO CAPE CANAVERAL...FL WITH A RIDGE AXIS EXTENDING FROM A 1020 MB HIGH PRES SYSTEMS NEAR 29N64W W ALONG 28W TO 29W TO 75W AND THEN TURNING SW INTO THE STRAITS OF FL. SHORTWAVE ENERGY ASSOCIATED WITH THE SOUTHERN END OF THE TROUGH OVER THE GULF OF MEXICO IS EXPECTED TO LIFT NORTHWARD THROUGH THE EASTERN GULF OVER THE WEEKEND AND THEN DROP SE OFF THE NE FL COAST AS IT ROUNDS THE HIGH PRES IN THE SE GULF OF MEXICO. AT THE SURFACE...THE ASSOCIATED TROUGH WILL TRANSITION TO A WAVY FRONTAL BOUNDARY AS IT IS DRAGGED NORTHWARD THROUGH THE FL PENINSULA AND THE MODELS AGREE UPON A SURFACE LOW BEING INDUCED ALONG THE STATIONARY BOUNDARY OFF THE NE FL COAST BY SUN NIGHT. THE 12Z MODELS HAVE COME INTO BETTER AGREEMENT ON A FORECAST THAT TAKES THE SURFACE WAVE FROM OFF N FL ON A SE TRACK ALONG THE STRENGTHENING BAROCLINIC BOUNDARY ASSOCIATED WITH THE LOW CURRENTLY OFF THE DELMARVA COAST AS IT FINALLY MOVES NORTHEASTWARD EARLY NEXT WEEK. MEANWHILE...THE BOUNDARY SHOULD WEAKEN OVER THE FL PENINSULA AS THE MAIN SURFACE LOW SHIFTS E AND THEN NE ON TUE. ELSEWHERE...THE REMNANTS OF THE WEAK SURFACE LOW PRES SYSTEM THAT HAD PERSISTED FOR THE LAST TWO DAYS N OF PUERTO RICO SHOULD BE STEERED NW ALONG THE SW SIDE OF THE AFOREMENTIONED HIGH PRES SYSTEM E OF THE AREA AND INTO THE LEADING EDGE OF THE TROUGHING STRETCHED ACROSS THE SW N ATLC...PUSHING ITS REMNANTS NE OUT OF THE AREA OVER THE WEEKEND. CARIBBEAN...A TROPICAL WAVE ALONG 80W WILL MOVE W THROUGH THE WESTERN CARIBBEAN TODAY AND SAT. STRONGEST WINDS ARE TO 20 KT IN THE CARIBBEAN AND LIE E OF THE WAVE. WINDS SHOULD DIMINISH IN THE CENTRAL CARIBBEAN OVER THE WEEKEND AS THE HIGH PRES OVER THE CENTRAL N ATLC WEAKENS. STRONGER WINDS WILL SHIFT INTO THE NW CARIBBEAN WHERE SE FLOW STEERED BETWEEN HIGH PRES OVER THE SE GULF OF MEXICO AND LOW PRES OVER THE WESTERN GULF WILL BRING WINDS TO 20 KT OVER FAR WESTERN WATERS SAT THROUGH MON. TUE LOOKS LOOKS TO BE A DAY OF WINDS UNDER 20 KT AND SEAS 4 FT OR LESS OVER THE ENTIRE CARIBBEAN. TROPICAL N ATLC...WEAK TRADES OF 15 KT OR LESS AND SEAS OF 4 TO 7 FT WILL PERSIST THROUGH THE PERIOD IN THE TROPICAL N ATLC ZONE. LONG PERIOD E SWELL FROM HURRICANE FRED SHOULD MOVE INTO THE ZONE OVER THE WEEKEND FOLLOWED BY NORTH SWELL ON MONDAY WHICH IS EXPECTED TO RAISE SIGNIFICANT WAVE HEIGHTS A FOOT OR TWO AS IT TRAVELS SOUTH THROUGH THE ZONE. FINALLY...MOST OF THE MODELS CARRY THE REMNANTS OF FRED EASTWARD TOWARD 45W TO 50 W ON TUE...WITH SIGNIFICANT SPREAD IN THE LATITUDE OF THE SURFACE LOW. THE OFFICIAL NHC FORECAST HAS THE 20 KT REMNANT LOW AT 23N49W WED MORNING. HOWEVER...WHAT IS LEFT OF FRED WILL BEGIN TO APPROACH THE BUILDING RIDGE AXIS TO ITS N BY MON AND THE EASTERLY WINDS ON THE NORTHERN SIDE OF THE REMNANT LOW ARE EXPECTED TO EXPAND UNDER THE TIGHT PRES GRADIENT. WARNINGS ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE $$ FORECASTER SCHAUER CLARK