000 AGXX40 KNHC 010830 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 430 PM EDT TUE SEP 01 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... WEAK TROUGH CONTINUES TO LINGER OVER NORTHERN GULF WATERS WITH MINOR IMPACT ON WIND AND SEAS EXCEPT CHANGES IN WIND DIRECTIONS. PRES GRADIENT REMAINS FLAT ACROSS ENTIRE GULF WITH LIGHT TO GENTLE BREEZE NOTED AND EXPECTED THROUGH FORECAST PERIOD. MODEL GUIDANCE MAINTAIN ISOBAR DIFFERENCE OF 2-3 MILLIBAR THROUGH SAT. CARIBBEAN AND TROPICAL N ATLC W OF 55W... TROPICAL WAVE ALONG 81W PROVIDES SUPPORT FOR FRESH BREEZE OVER WESTERN CARIBBEAN WITH MODERATE SWELLS BRINGING SEAS TO 6-7 FT. OUTSIDE THE INFLUENCE OF TROPICAL WAVE THE WINDS AND SEAS REMAIN QUITE TAME FOR THIS TIME OF THE YEAR. LOW PRES IN TROPICAL ATLC MAY HAVE FLATTEN PRES GRADIENT ACROSS EASTERN CARIBBEAN DIMINISHING TO A FRESH BREEZE FROM THE STRONG ONE WE HAD 24 HRS AGO. LOW ALSO PRODUCING STRONG WINDS AND SEAS WHICH SEEM TO SEEP THROUGH ATLC PASSAGES BETWEEN LESSER ANTILLES ISLANDS AND INCREASING N OF 15N E OF 66W. FURTHER DEVELOPMENT...POSSIBLY INTO TROPICAL CYCLONE...OF THIS SYSTEM EXPECTED OVER NEXT 48 HRS SO CARIBBEAN CONDITIONS NOT EXPECTED TO CHANGE UNTIL LOW PRES MOVES OUT OF AREA. FORECASTS CARRIES LOW PRES JUST N OFF PUERTO RICO SO SEEPAGE EXPECTED TO CHANGE TO MORE NORTHERN PASSAGES. QUIKSCAT SHOWS AREA OF NEAR GALE WINDS JUST N AND NW OF CONVECTIVE BURST WHICH IS SEPARATED TO THE NE FROM MAIN CENTER. INTERESTS ACROSS THE ANTILLES SHOULD MONITOR PROGRESS OF SYSTEM. SW N ATLC S OF 31N AND W OF 65W... ATLC STATIONARY SURFACE TROUGH FROM 30N71W TO 20N74W ASSOCIATED WITH UPPER LEVEL CIRCULATION AT 23N72W. TROUGH EFFECTIVELY MAINTAINS WEAK GRADIENT SINCE CENTRAL ATLC RIDGE HAS BACKED NE AS LOW PRES IN TROPICAL ATLC MOVES NW APPROACHING SE CORNER OF SW N ATLC BASIN. GENTLE BREEZE EXPECTED W OF 70W WHILE SE CORNER STARTS GETTING IMPACT FROM LOW PRES IN TROPICAL ATLC... POSSIBLE TROPICAL CYCLONE WITHIN NEXT 48 HRS. MODEL GUIDANCE SPLIT ON INTENSITY...TRACK AND TIMING OF LOW PRES WITH GFS DIFFERING SUBSTANTIALLY FROM EUROPEAN...NOGAPS AND NAM AND THESE DIFFERING AMONG THEMSELVES IN INTENSITY WHILE MORE IN LINE WITH W-NW TRACK. FORECAST LEANING MORE INTO THESE THAN RELYING IN GFS...BUT WITH HIGH UNCERTAINTY. WARNINGS ATLC... .NONE CARIBBEAN... .NONE. GULF OF MEXICO... .NONE $$ FORECASTER WALLY BARNES