000 AGXX40 KNHC 210641 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 245 AM EDT FRI MAR 21 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. UPPER LEVELS...A STRONG SHORTWAVE HAS MOVED E OFF THE CONUS BUT STILL TRAILS UPPER TROUGH SW ACROSS N FL INTO SW GULF OF MEXICO. AN UPPER ANTICYCLONE IS NEAR 23N67W RIDGING SW OVER THE NW CARIBBEAN AND GULF OF HONDURAS. THE UPPER RIDGE WILL SHIFT E TO ALONG 55W EARLY NEXT WEEK AS THE TROUGH SWINGS E AND IS REINFORCED BY A SECONDARY TROUGH THAT WILL SWING THROUGH THE DISCUSSION AREA SUN THROUGH TUE. LOW LEVELS...A COLD FRONT EXTENDS FROM 31N70W SW ACROSS THE NW BAHAMAS AND THE STRAITS OF FL TO A WEAK FRONTAL WAVE LOW AT 23N86W 1014MB...WITH A FRONTAL TROUGH CONTINUING S QUASI STATIONARY ACROSS THE YUCATAN PENINSULA. SURFACE HIGH PRES 1024 MB HAS BUILT IN THE WAKE OF THE FRONT OVER COASTAL LA. HIGH PRES IS OVER THE ATLC NEAR 27N59W 1022 MB. EXPECT THE SURFACE LOW OVER THE SE GULF TO DRIFT N DRAGGING THE FRONT BACK N AS A WEAK WARM FRONT OVER THE NW BAHAMAS AND STRAITS OF FL THROUGH SAT. THEN THE LOW WILL MOVE NE...OR PERHAPS JUMP...ACROSS FL SAT NIGHT TO NEAR 27N76W WHILE TRAILING A FRONTAL TROUGH SW OVER THE SE GULF OF MEXICO. A SECONDARY COLD FRONT WILL MOVE INTO THE AREA ALONG 31N79W ACROSS N FL TO SE TX SUNSET SAT. THIS SECOND FRONT WILL MERGE WITH THE INITIAL BOUNDARY AND EXTEND FROM BERMUDA ACROSS THE CENTRAL BAHAMAS TO BELIZE SUNRISE MON AND MOVE SE OF ATLC AREA TUE WHILE LOSING IDENTITY OVER THE CARIBBEAN...AS HIGH PRES BUILDS ACROSS THE ENTIRE AREA. GULF OF MEXICO...NE WINDS AT 20 KT OVER THE NE WATERS WILL DIMINISH THIS AFTERNOON. SOME UNCERTAINTY ON STRENGTH OF WINDS OVER N SEMICIRCLE OF LOW PRES AS IT DRIFTS N TONIGHT AND SAT. WILL GO WITH 15 KT AND SUBSIDING SEAS AROUND 6 FT SAT MORNING. ONLY EXPECTING NORTHERLY WINDS TO INCREASE TO 20 KT BEHIND THE SECOND FRONT WITH SOUTHERLY RETURN OVER THE GULF W OF 90W SUNSET TUE. SW N ATLC...SW FLOW AHEAD OF FRONT IN 20-25 KT RANGE WITH SEAS TO 12 FT CONFIRMED BY ALTIMETER PASS LATE THU. W OF FRONT N TO NE WINDS 20 KT. WINDS WILL DIMINISH TO 15 KT OR LESS ALL AREAS TONIGHT AS FRONT STALLS. EXPECT WINDS INCREASE AGAIN TO 15 TO 20 KT NEAR FRONTAL WAVE LOW PRES SAT NIGHT AND SUN AND CONTINUE TO INCREASE TO 20 TO 25 KT BEHIND SECOND COLD FRONT MON MAINLY OVER WATERS S OF BERMUDA. LARGE NORTHERLY SWELLS CURRENTLY E OF BAHAMAS WILL PASS SE OF THE AREA TONIGHT. CARIBBEAN AND TROPICAL N ATLC...NE TO E TRADES OVER THE CENTRAL CARIBBEAN WILL GRADUALLY DIMINISH LATE THIS WEEKEND AS HIGH PRES N OF THE AREA WEAKENS AND SHIFTS E. LARGE LONG PERIOD N SWELL STILL PROPAGATING THROUGH EXPOSED ATLC PASSAGES NE CARIBBEAN. THE LARGEST SWELL WILL PASS SE OF TROPICAL ATLC ZONE SAT WITH SEAS BELOW 10 FT ALL AREAS SUN NIGHT. NE TO E TRADES AT 15 TO 20 KT ALL WATERS MON NIGHT AND TUE. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER NELSON