000 AGXX40 KNHC 201815 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 215 PM EDT SAT SEP 20 2008 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO... CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. SW N ATLC... A PAIR OF SFC TROUGHS GOVERN THE PATTERN OVER THE SW N ATLC WITH THE MORE DOMINANT TROUGH OVER THE FAR NW PORTION OF THE AREA ALONG 31N77W TO 29N81W WHICH DIVIDES NE WINDS OF 20 KT FROM LIGHT E TO SE WINDS. TROUGH ALONG 31N71W TO 23N76W IS WEAKENING WITH TIME. THE FAR NW TROUGH SHOULD REMAIN IN PLACE THROUGH THE SHORT TERM AND PLAY A SIGNIFICANT ROLE IN THE LONG TERM. THE MAIN FCST ISSUE AS WAS THE CASE YESTERDAY IS THE DEVELOPMENT OF AN AREA OF STRONG NE WINDS OVER THE N PORTIONS OF THE AREA AND MODEL DIFFERENCES ON THE EVOLUTION OF THIS WIND FIELD. THE NOGAPS/NAM AND NOW THE GFS ARE IN AGREEMENT IN DEVELOPING A LOW OF TROPICAL ORIGIN ASSOCIATED WITH THE TROPICAL WAVE ALONG 66W AND MOVING IT NWWD INTO THE ZONE BY TUE AND MOVE IT NWD THROUGH THU. THE NOGAPS/NAM SOLUTIONS ARE DISCOUNTED OWING TO INITIAL PLACEMENT ERRORS OF THE INITIAL TROUGH AXIS. THE UKMET AND ECMWF TAKE THE NORTHERN EXTENT OF THE TROPICAL WAVE AND MERGE IT WITH A VIGOROUS BAROCLINIC SYSTEM OFF THE SE COAST BY LATE WED AND THU. THE GFS KEEPS THE TROPICAL LOW AND THE MID LATITUDE AS SEPARATE SYSTEMS. ALTHOUGH IT APPEARS THE GFS IS THE BEST COMPROMISE BETWEEN THE TWO MODEL CAMPS...WILL PLAN TO LEAN TOWARD THE UKMET/ECMWF SOLUTIONS UNTIL THE WAVE/LOW IN THE CARIBBEAN SHOWS FURTHER DEVELOPMENT. THUS WE ARE DEALING WITH A LOW CONFIDENCE FCST IN THE EXTENDED AT THIS TIME. IN ANY EVENT WILL HIGHLIGHT STRONG NE WINDS OF 20-25 KT POSSIBLY 30 KT OVER THE FAR NW PORTION OF THE AREA WITH BROAD SE WINDS OVER THE REMAINDER OF THE AREA. CARIBBEAN AND TROPICAL N ATLC... ALL EYES ARE ON A TROPICAL WAVE ALONG 66W AND ASSOCIATED 1010 MB LOW NEAR 15N66W AND THE AREA OF CONVECTION EXTENDING WELL E OF THE WAVE OVER THE LESSER ANTILLES AND THE WRN PORTIONS OF THE TROPICAL N ATLC. WAVE AND LOW SEPARATES NE-E WINDS OVER PUERTO RICO/U.S. VIRGIN ISLANDS FROM MODERATE S TO SW FLOW W OF THE LESSER ANTILLES. MODERATE E WINDS TO 20 KT N AND E OF THE WAVE AND LOW WILL PERSIST OVER THE N PORTIONS OF THE TROPICAL N ATLC ZONE THROUGH LATE SUN/EARLY MON. WAVE MOVES WWD WITH A BROAD WEAK PRESSURE PATTERN IN ITS WAKE AND SUB-NORMAL TRADES. GULF OF MEXICO... PERSISTENT TROUGH OVER THE FAR W GULF ALONG 96W SHOWS LITTLE IN THE WAY OF MOVEMENT. THIS TROUGH SHOULD SLOWLY WEAKEN THROUGH THE PERIOD BUT MAINTAIN ITSELF IN SOME FORM INTO MID-WEEK. THE TROUGH WILL DIVIDE NW TO N WINDS ALONG THE IMMEDIATE MEXICAN COAST FROM ELY WINDS OF 10-15 KT OVER THE REMAINDER OF THE GULF. THE ONLY CHANGE IN THIS OVERALL SCENARIO IS AN INCREASE IN NE WINDS TO 15-20 KT OVER THE N PORTIONS OF THE GULF E OF 90W WED BROUGHT ABOUT BY BUILDING HIGH PRESSURE OVER THE ERN CONUS. THESE WINDS WILL SPREAD OVER MOST OF THE NORTHERN GULF E OF 93W BY LATE THU. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER COBB. TROPICAL PREDICTION CENTER.