000 AGXX40 KNHC 290653 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 250 AM EDT TUE APR 29 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. UPPER LEVELS... A RATHER STRONG SHORTWAVE TROUGH HAD MOVED INTO THE NW GULF OF MEXICO...AND IS SUPPORTING A LATE SEASON BONAFIDE COLD FRONT THAT CURRENTLY EXTENDS FROM THE FLORIDA SW COAST TO THE NE YUCATAN PENINSULA. STILL ABUNDANT UPPER LEVEL MOISTURE EXISTS AHEAD OF THE TROUGH SE OF A LINE FROM 30N86W TO 25N91W TO 22N98W...AND IS BEING ADVECTED EWD ACROSS MUCH OF THE MIDDLE AND ERN GULF AND ACROSS FLORIDA. THE TROUGH IS FORECAST BY NWP MODELS TO MOVE INTO THE NW ATLC LATE TONIGHT...THEN BEGIN TO FLATTEN OUT AS IT MOVES E OF THE SW N ATLC LATE WED NIGHT. LARGE N ATLC CYCLONIC VORTEX HAS ITS ASSOCIATED LONG WAVE TROUGH ALOFT DIGGING SW INTO TRPCL ATLC FROM 22N55W TO 11N60W. HIGHLY AMPLIFIED RIDGING BEHIND THIS TROUGH IS SLIDING EWD WITH ASSOCIATED DRY AIR CURRENTLY PRESENT OVER MUCH OF THE SW N ATLC AND NRN CARIBBEAN SEA GRADUALLY BEING REPLACED BY THE UPPER LEVEL MOISTURE SPILLING IN FROM THE GULF OF MEXICO. SURFACE... GULF OF MEXICO...THE COLD FRONT MENTIONED ABOVE BROUGHT GALE WINDS TO THE FAR WRN PORTION OF THE SW GULF YESTERDAY...BUT QUIKSCAT DATA FROM AROUND 0030 UTC LAST NIGHT INDICATES THAT WINDS IN THAT PART OF THE GULF HAVE DIMINISHED TO BELOW GALE FORCE AS HAD BEEN PROJECTED BY THE GFS MODEL. HIGHEST WINDS NOTED BY THIS PASS ARE NE AT 25 KT S OF ABOUT 23N AND W OF 95W. WINDS ELSEWHERE ACROSS THE WRN GULF ARE N-NE 20 KT...AND N 10-15 KT ACROSS REMAINDER OF THE GULF. MODELS SUGGEST THAT A WEAKER COLD FRONT WILL MOVE INTO THE TEXAS AND LOUISIANA COAST LATE FRI NIGHT AND SAT MORNING. SW N ATLC... THE GULF OF MEXICO COLD FRONT EXTENDS NE ACROSS S FLORIDA AND N TO ALONG 80W. WINDS AHEAD OF IT HAVE INCREASED TO 20 KT AS SEEN IN A FEW SHIP REPORTS OVER THE NW PORTION. THESE WINDS WILL SPREAD E ACROSS THE NRN PART OF THE AREA THROUGH LATE THIS AFTERNOON AS THE FRONT REACHES FROM 31N67W TO VICINITY OF SE BAHAMAS TONIGHT AND WEAKENS. IN ADVANCE OF THE FRONT... MODELS ARE FAIRLY GOOD AGREEMENT THAT HIGH PRES OF 1021 MB ANALYZED NEAR 29N68W WILL SHIFT SE OF THE AREA BY EARLY THIS EVENING AS IT WEAKENS. TIGHT PRES GRADIENT OVER THE FAR SRN WATERS IS RESULTING IN E WINDS OF 15-20 KT BETWEEN THE SE BAHAMAS AND GREATER ANTILLES ISLAND CHAIN. EXPECT THESE WINDS TO DECREASE TO 10 KT BY TONIGHT AS THE HIGH WEAKENS. BY SAT MORNING...A NEW HIGH CENTER MOVES INTO THE NE PART OF THE AREA THEN QUICKLY MOVES E OF THE AREA BY LATE SAT NIGHT...ALLOWING SLY FLOW TO INCREASE OVER THE FAR NW PART ON SAT. CARIBBEAN AND TROPICAL ATLC... NWP MODELS STILL SUGGEST THAT FRONT WILL HAVE LITTLE IMPACT ON WINDS IN THE CARIBBEAN...EXCEPT FOR BRINGING NE WINDS OF 10 KT TO THE NW SECTION THIS MORNING THROUGH TONIGHT. WITH ATLC HIGH SHIFTING EWD AND WEAKENING...TRADES OVER MUCH OF THE AREA WILL BE IN THE LIGHT RANGE EXCEPT FOR S OF 14N INCLUDING THE IMMEDIATE S AMERICAN COAST WHERE NE-E WINDS OF 15-20 KT WILL CONTINUE THROUGH THU...AND REMAIN UNCHANGED NEAR THE COLOMBIAN COAST THROUGH SAT. WARNINGS... ATLC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. .FORECASTER AGUIRRE. TROPICAL PREDICTION CENTER.