000 AGXX40 KNHC 011743 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 145 PM EDT THU NOV 01 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... HIGH PRES CENTERED AT 25N88W WILL DRIFT W-NW ALLOWING THE PORTION OF A COLD FRONT OVER THE CENTRAL WATERS TO CONTINUE SE AND PASS THROUGH FL STRAITS FRI AFTERNOON. BY THEN THE HIGH CENTER WILL BEGIN TO SHIFT NE REACHING THE FL BIG BEND AREA FRI NIGHT WITH A RIDGE EXTENDING WSW TO THE TX COASTAL BEND. E-SE RETURN FLOW WILL INCREASE 10-15 KT ACROSS THE SW AND W CENTRAL WATERS FRI NIGHT-SAT NIGHT...EXCEPT 15-20 KT BRIEFLY DURING THE EVENINGS ALONG NW YUCATAN COAST. THE HIGH WILL SHIFT E OF FL ON SUN WITH THE ANTICYCLONIC FLOW AROUND THE RIDGE DIMINISHING TO 5-10 KT ACROSS THE ENTIRE GULF. THE RIDGE WILL SHIFT A LITTLE S ON SUN NIGHT ALLOWING AN INITIALLY WEAK COLD FRONT...ACCOMPANIED BY 10-15 KT SW-W-NW WIND SHIFT...TO PASS THROUGH THE NORTHERN WATERS MON-MON NIGHT. LATEST GUIDANCE IS STRONGER WITH THE POST FRONTAL FLOW AND NOW SUGGESTS A REINFORCING 15-20 KT NLY SURGE WILL CREEP INTO N-CENTRAL WATERS TUE MORNING...THEN SPREAD RAPIDLY S ACROSS THE ENTIRE GULF BY TUE EVENING. THIS IS EXPECTED TO BE A SHORT TERM BLAST WITH THE NLY WINDS DIMINISHING AGAIN LATE TUE NIGHT INTO WED MORNING. BLENDED LATEST GFS/ECMWF WITH PREVIOUS PACKAGE. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE SOUTHERN SEGMENT OF A FRONTAL TROUGH IS WASHING OUT OVER AND JUST S OF THE WINDWARD PASSAGE WITH SHOWERS AND OCCASIONALLY A TSTM IGNITING BETWEEN E CUBA AND JAMAICA. THE NE FLOW ALONG THE FRONT HAS DIMINISHED TO 10-15 KT IN THE WINDWARD PASSAGE. A BROAD LOW LEVEL TROUGH IS ANALYZED N-S ALONG 77W AND IS ACCOMPANIED BY SIGNIFICANT CONVECTION OVER THE WATERS S OF 13N W OF 75W INCLUDING THE NLY APPROACHES TO THE PANAMA CANAL. THIS LOW LEVEL TROUGH IN UNDER AND AREA OF UPPER DIFFLUENCE ALONG THE W PERIPHERY OF AN UPPER RIDGE AND JUST AHEAD OF A STRONG UPPER TROUGH OVER THE NW CARIBBEAN. THIS UPPER SUPPORT IS EXPECTED TO PERSISTS AS THE THE TROUGH DRIFTS WESTWARD. GUIDANCE VARIES SOMEWHAT...BUT GENERALLY EXPECT A WEAK LOW PRES TO DEVELOP AT 11N ALONG THE TROUGH AXIS FRI-FRI NIGHT...THEN MEANDER ON SAT-SUN...POSSIBLE MAINTAINING A WEAK CIRCULATION AS IT PASSES ACROSS THE COAST OF NICARAGUA LATE SUN NIGHT. THIS TROUGH IS EXPECTED TO BE THE BOUNDARY BETWEEN N-NE 10-15 KT WINDS AND NE-E 15-20 KT TO E OF THE TROUGH THROUGH THE PERIOD. POPULATED LATEST GFS/ECMWF AND NWW3 WITH PREVIOUS PACKAGE FOR GRIDS. SOUTHWEST NORTH ATLC S OF 31N W OF 55W... A FRONTAL TROUGH EXTENDS FROM NEAR 31N63W TO THE WINDWARD PASSAGE AND A SECONDARY SURGE...ANALYZED AS A COLD FRONT... EXTENDS FROM 31N70W TO SE FL. NOTE THAT TWO MORE POST-FRONTAL TROUGHS ARE EVIDENT TO THE W OF THIS COLD FRONT WITH THE EASTERNMOST BOUNDARY OVER THE NW WATERS AND THE SECOND TROUGH APPROACHING THE GA COAST. EXPECT THE TROUGH OVER LAND TO BECOME THE MAIN FOCUS OVER THE NEXT FEW DAYS AS IT IS REINFORCED AND TRANSITIONS TO A COLD FRONT WHICH WILL SWEEP E AND EVENTUALLY OVERTAKE ALL THE WEAKENING BOUNDARIES. THIS STRONGER FRONT SHOULD REACH FROM BERMUDA TO THE FL STRAITS FRI AFTERNOON AND MERGE WITH ALL THE BOUNDARIES ALONG A LINE FROM 31N60W TO 19N68W SAT AFTERNOON. CONDITIONS WILL DIMINISH W OF THIS BOUNDARY OVER THE WEEKEND AS A WEAK SURFACE HIGH SHIFTS FROM THE NE GULF ACROSS N FL TO NEAR 30N74W WITH A RIDGE EXTENDING SE ACROSS THE SUBTROPICAL WATERS N OF THE BAHAMAS BY SUN NIGHT. THE SURFACE HIGH WILL RACE NE EARLY NEXT WEEK PASSING BERMUDA MON NIGHT WITH THE RIDGE RE-ORIENTATING SW TO CENTRAL FL GRADUALLY REDIRECTING DOMINATE W SWELL TO N-NE NEXT WEEK. BLENDED GFS/ECMWF WITH PREVIOUS OFFICIAL. 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 NELSON