000 AGXX40 KNHC 121841 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 240 PM EDT SAT SEP 12 2009 GULF OF MEXICO...A STATIONARY FRONT LIES WITHIN 60 NM OF THE N GULF COAST FROM CEDAR KEY...FL TO A 1006 MB LOW PRES SYSTEM OFF THE TX COAST NEAR 28N96W. STRONGEST WINDS LIE JUST OFF THE CENTRAL GULF COAST BETWEEN THE BOUNDARY AND SHORE...WITH SEVERAL BUOY REPORTS SHOWING E WINDS AT 20 KT. SCATTERED MODERATE CONVECTION IS PLENTIFUL IN THE NORTHERN GULF AND CAN CURRENTLY BE FOUND IN TWO BATCHES. THE EASTERN AREA OF SHOWERS AND THUNDERSTORMS IS ASSOCIATED WITH A ZONALLY ELONGATED MID LEVEL VORTICITY MAX THAT IS EXPECTED TO SHIFT SE AWAY FROM THE GULF SUN...ROTATING AROUND THE BUILDING RIDGE OVER THE SE GULF. THE SECOND AREA IS OVER THE NW GULF IN THE MEAN...MOIST SOUTHERLY FLOW ON THE EASTERN SIDE OF A DEEPENING MID LEVEL LOW OVER TX ASSOCIATED WITH THE SURFACE LOW IN THE NW GULF. MEAN TROUGHING OVER THE NW GULF AND RIDGING OVER THE SE GULF SHOULD PERSIST SUN 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 TUE AND WED. THE GFS IS FASTER THAN THE MODEL CONSENSUS TO CARRY THE ANCHOR SURFACE LOW E INTO THE LOWER MISSISSIPPI VALLEY...SO A SLOWER FRONTAL SOLUTION THAN THE GFS WAS USED FOR THE FORECAST. SW N ATLC...A STATIONARY BOUNDARY LIES FROM 31N77W TO 1013 MB LOW PRES NEAR 29N80W TO DAYTONA BEACH...FL. THIS LOW PRES SYSTEM WILL PASS NE OUT OF THE FORECAST AREA SUN MORNING. MEANWHILE...THE ZONALLY ELONGATED SHORTWAVE ENERGY SUPPORTING THE CONVECTIVE ACTIVITY IN THE NE GULF OF MEXICO IS EXPECTED TO BREAK AWAY FROM THE INFLUENCE OF THE DEEP-LAYER LOW OVER TX AS RIDGING BUILDS OVER THE SE GULF OF MEXICO. THE ENERGY WILL MOVE SE OFF THE NE FL COAST AND INDUCE A NEW SURFACE LOW ALONG THE FRONTAL BOUNDARY OVER FORECAST WATERS SUN NIGHT. AT THE SAME TIME...NORTHERN STREAM TROUGHING OVER THE WESTERN N ATLC WILL AMPLIFY...TURNING THE STATIONARY BOUNDARY INTO A COLD FRONT. THE MODELS CONTINUE TO 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 THROUGH MON. THE FORECAST IS CONSIDERABLY MORE UNCERTAIN FOR TUE AND WED WITH THE MODELS GENERALLY AGREEING ON LEAVING A SURFACE LOW MEANDERING IN THE VICINITY OF THE NORTHERN BAHAMAS AS THE DEEP LAYER TROUGH MOVES NE INTO THE CENTRAL N ATLC. CARIBBEAN...A TROPICAL WAVE ALONG 86W WILL MOVE THROUGH THE GULF OF HONDURAS BY SUNSET. STRONGEST WINDS ARE S AT 20 KT IN THE YUCATAN CHANNEL. AND THE 1128 UTC QUIKSCAT PASS CONFIRMS 20 KT WINDS W OF 85W. THE SAME QUIKSCAT PASS SAW A SMALL AREA OF 20 TO 25 KT WINDS ALONG THE COAST OF COLOMBIA...BUT THESE WINDS IN THE CENTRAL CARIBBEAN SHOULD DIMINISH OVER THE WEEKEND AS THE HIGH PRES OVER THE CENTRAL N ATLC WEAKENS. STRONGER WINDS HAVE ALREADY SHIFTED INTO THE NW CARIBBEAN WHERE SE FLOW IS STEERED BETWEEN HIGH PRES OVER THE SE GULF OF MEXICO AND LOW PRES OVER THE WESTERN GULF...MAINTAINING WINDS TO 20 KT OVER FAR NORTHWESTERN WATERS THROUGH MON. WINDS UNDER 20 KT AND SEAS 5 FT OR LESS ARE EXPECTED OVER THE ENTIRE CARIBBEAN TUE AND WED. 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 LATER TODAY FOLLOWED BY NORTH SWELL ON SUNDAY 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 55W BY WED...WITH SIGNIFICANT SPREAD IN THE LATITUDE OF THE REMNANT TROUGH. THE OFFICIAL NHC FORECAST HAS A 20 KT REMNANT LOW AT 23N44W TUE MORNING AND THEN DISSIPATES THE SYSTEM. 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