000 AGXX40 KNHC 230645 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 245 AM EDT SUN SEP 23 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... WEAK HIGH PRES IS IN PLACE OVER THE NORTHERN GULF THIS MORNING WITH A DEEP LAYER SOUTHERN STREAM TROUGH OVER FLORIDA AND A TROPICAL WAVE IN THE BAY OF CAMPECHE. THE WAVE WILL CONTINUE W WITH LITTLE FANFARE INTO EARLY MON BEFORE DISSIPATING OVER MEXICO...PRIMARILY SERVING AS A FOCUS FOR CONVECTION. A WEAK COLD FRONT WILL MOVE THROUGH THE NORTHERN GULF TODAY AND DISSIPATE OVER THE WESTERN GULF BY MON NIGHT AS THE EASTERN PORTION CONTINUES S INTO SOUTHERN FL AND THE KEYS WHERE IT SHOULD STALL ON TUE. EASTERLY WINDS WILL INCREASE TO A FRESH BREEZE AND SEAS TO 4-5 FT PRIMARILY OVER THE WEST CENTRAL GULF TONIGHT THROUGH MON AHEAD OF THE FRONT. THE MODELS ARE IN REASONABLE AGREEMENT ON THE TIMING AND STRENGTH OF THIS FRONT OVER THE GULF AS WELL AS THE OTHER FEATURES. THE FRONT WILL DISSIPATE OVER THE EASTERN GULF BY WED...LEAVING HIGH PRES NEAR SOUTH CAROLINA TO STEER THE LIGHT TO MODERATE WINDS OVER THE GULF. A BLEND OF THE 00Z GFS AND ECMWF WILL BE USED TO ADJUST THE FORECAST. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... THE SOUTHERN STREAM OF THE SPLIT UPPER JET FEEDING INTO THE DEEP LAYER TROUGH OVER THE EASTERN U.S. IS DIRECTING TROPICAL MOISTURE NEWD ACROSS FL AND THE WESTERN BAHAMAS. THIS SURFACE TROUGH WILL CONTINUE TO BE A FOCUS FOR CONVECTION UNTIL IT MERGES WITH THE INCOMING COLD FRONT. THE COLD FRONT IS EXPECTED TO MOVE SOUTHWARD ALONG THE E COAST OF FLORIDA TODAY THROUGH TUE WHEN IT WILL STALL OVER S FL. THE 00Z ECMWF HAS COME INTO BETTER AGREEMENT WITH THE GFS FORECAST ON THE TIMING OF THE FRONTAL BOUNDARY AS IT MOVES SEWD BY TRENDING SLOWER/MORE TO THE W. A BLEND OF THE 00Z ECMWF AND GFS WILL BE USED TO ADJUST THE FORECAST. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE 0238 UTC ASCAT PASS SHOWED STRONG EASTERLY WINDS ARE IN PLACE NEAR THE COAST OF COLOMBIA THIS MORNING. THESE WINDS ARE DRIVEN BY THE PRES GRADIENT BETWEEN RIDGING OVER THE SE U.S. AND LOWER PRES OVER MAINLAND SOUTH AMERICA. THE HIGH PRES IS EXPECTED TO BUILD AS THE COLD FRONT MOVES THROUGH THE GULF OF MEXICO TODAY INTO EARLY MON AND THEN WEAKEN. WINDS AND SEAS ALONG THE COAST OF COLOMBIA WILL ALSO DIMINISH AS THE PRES GRADIENT WEAKENS. THE 00Z GFS HAS A BETTER HANDLE ON THE CURRENT CONDITIONS THAN THE ECMWF AND CONSISTENTLY HAS BEEN SHOWING SLIGHTLY STRONGER WINDS NEAR COLOMBIA. IT WILL BE RELIED ON FOR ADJUSTMENTS TO THE FORECAST HERE. ELSEWHERE...A WEAK TROPICAL WAVE ANALYZED NEAR 53W HAS BECOME CONSIDERABLY HARDER TO FIND OVER THE PAST 24 HOURS AS IT HAS ENCOUNTERED 25-30 KT CONVERGENT MID LEVEL FLOW. BUOYS 41040 AND 41101 WERE REPORTING 19 KT NE WINDS AT 0600 UTC WITH 9 AND 8 FT SEAS...RESPECTIVELY. THE 2204 UTC JASON1 PASS CONFIRMED SEAS TO 9 FT BUT THE 0058 UTC ASCAT PASS DOES NOT SHOW WINDS TO 25 KT AT THE SURFACE. CONFIDENCE IS LOW IN TRACKING THE WAVE WESTWARD INTO THE CARIBBEAN...BUT THE FORECAST CALLS FOR THE WAVE TO PASS THROUGH THE TROPICAL N ATLC ZONE TODAY THROUGH MON...MOVE INTO THE CARIBBEAN MON NIGHT...AND PASS THROUGH THE CENTRAL CARIBBEAN BY THU. THIS IS SLIGHTLY FASTER THAN EARLIER THINKING. AGAIN...CONFIDENCE IS LOW HERE AND A BLEND OF THE 00Z GFS AND ECMWF WILL BE USED TO ADJUST THE WIND FORECAST. SEAS WILL RELY MORE HEAVILY ON THE WW3 AS ITS HIGHER WAVE HEIGHTS IN THE CARIBBEAN HAVE BEEN PERFORMING BETTER THAN THE ECMWF WAVE MODEL AS OF LATE. NOTE...GRIDDED MARINE FORECAST IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .NONE. CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER