000 AGXX40 KNHC 200655 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 155 AM EST WED DEC 20 2006 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... HIGH PRESSURE CENTERED OVER THE MIDWEST WITH ASSOCIATED RIDGE BUILDING EWD TO THE MID-ATLC HAS RESULTED IN THE ADVERTISED INCREASE IN WINDS OVER THE E-CENTRAL PORTIONS OF THE GULF. BUOY 42001 AND SOMBRERO KEY CMAN SITES HAVE REPORTED 23-25 KT WINDS OVER THE PAST HOUR. THE 0002 UTC QUIKSCAT PASS INDICATED THE SAME NARROW BELT OF 20 KT WINDS NOTED EARLIER FROM THE STRAITS OF FLORIDA NW TOWARDS THE LOUISIANA COAST. HIGH PRESSURE BUILDS SE AND INCREASES THE GRADIENT OVER THE GULF E OF 90W TODAY AND TONIGHT. WINDS DECREASE SOME AS A WEAK COLD FRONT MOVES OFF THE TEXAS COAST OVER NIGHT/EARLY THU WHERE THE MODELS REMAIN IN GENERAL AGREEMENT ON TIMING OF THE ENTRANCE OF THE FRONT INTO THE GULF AND THE DELAY IN THE INCREASE IN NLY WINDS BEHIND THE FRONT UNTIL THU NIGHT AND FRI WITH THE ARRIVAL OF THE BEST 1000-850 THICKNESS GRADIENT/CAA. MODEL DIFFERENCES ARISE WITH THE EJECTION OF THE LOW OVER THE WRN GULF AND THE EVENTUAL TRACK. THE GFS/GFS ENSEMBLES/ECMWF/CMC ARE SLOWER IN BRINGING THE LOW OUT INTO THE GULF VERSUS THE MORE PROGRESSIVE NOGAPS/UKMET SOLUTIONS WHICH HAVE A LOW OVER THE W GULF BY SAT EVENING. THE SOLUTIONS DIVERGE EVEN FURTHER BY LATE SUN WITH THE NOGAPS THE OBVIOUS OUTLIER WITH LOW PRESS WELL INTO THE ATLC ...THE CMC/GFS/GFS ENSEMBLES OVER THE NE GULF/SE US AND THE ECMWF/UKMET KEEPING A LOW IN THE CENTRAL GULF. GIVEN THE VAST DIFFERENCES A COMPROMISE POSITION IN THE N-CENTRAL GULF APPEARS REASONABLE. INCREASED CONFIDENCE IN GALES ON SUN AS MOST MODELS PRODUCE GALE FORCE WINDS ON SUN BEHIND THE LOW...EVEN THE USUALLY BENIGN NOGAPS. IN ADDITION THE GFS ENSEMBLES ARE INDICATING A 60% PROBABILITY OF GALES AS WELL. THIS IS A HIGHLY UNCERTAIN FORECAST LOADED WITH TIMING ISSUES AND ADJUSTMENTS ARE LIKELY IN THE COMING DAYS. SW N ATLC... RIDGE OF HIGH PRES HAS TEMPORARILY WEAKENED AND SLID SEWD WITH 20 KT WINDS CONFINED TO THE AREAS S OF 26N. A COLD FRONT CURRENTLY FROM SOUTH CAROLINA EWD INTO THE ATLC WILL DROP S AND ENTER THE AREA BY SUNRISE WITH A QUICKLY INCREASING PRES GRADIENT COVERING THE ENTIRE ZONE BY AFTERNOON WITH WINDS INCREASING TO 20-25 KT OVER MUCH OF THE AREA. HIGHEST WINDS ARE SHORT LIVED WITH MAXIMUM SEAS LIKELY NOT REACHED..THOUGH CANNOT RULE OUT SOME 10-11 FT SEAS AND SOME RESIDUAL SWELL PROPAGATING TOWARD THE FLORIDA COAST AND BAHAMAS. HIGH PRESS WEAKENS AND SLIDES SE THU/EARLY FRI WITH WINDS DECREASING TO 15-20 KT...HIGHEST FROM THE STRAITS OF FLORIDA EWD ACROSS THE BAHAMAS. WINDS THEN BEGIN TO VEER SE AND S OVER THE W PART ON FRI AND SAT AS THE HIGH SHIFTS E...AND THE PRES GRADIENT WILL REMAIN STRONG ENOUGH TO KEEP 15-20 KT IN THE FORECAST. A SECONDARY AREA OF LOW PRES AND FRONT MOVES ACROSS THE SE U.S. ON SUN WITH SWLY WINDS OVER THE NW PORTION OF THE AREA. THE MOVEMENT OF THE FRONT SWD INTO THE AREA IS VERY DEPENDENT ON THE STRENGTH AND EVOLUTION OF HIGH PRESS OVER THE NE AND MID-ATLC. THE ECMWF/NOGAPS ARE ALONE AT THIS TIME IN DEVELOPING A STRONGER DAMMING HIGH PRESS AND BACK DOOR FRONTAL PASSAGE INTO THE AREA ON SUN. CARIBBEAN AND TROPICAL ATLC... MODERATE TRADES OVER MOST OF THE CARIBBEAN AND TROPICAL N ATLC BEGIN TO INCREASE SLIGHTLY TONIGHT/THU OVER THE CARIBBEAN AS HIGH PRES STRENGTHENS TO THE N OF THE AREA. WINDS ALSO INCREASE SLIGHTLY OVER THE N PART OF THE TROPICAL ATLC WATERS THU NIGHT THROUGH SUN AS THE ATLC HIGH SHIFTS E SO THAT BY SAT AND SUN AREA OF 20 KT TRADES REACHES ITS MAXIMUM EXTENT WITH THE POSSIBILITY OF 30 KT WINDS ALONG THE IMMEDIATE COLOMBIAN COAST. WAVEWATCH MODEL IS NOW IN LINE WITH OBSERVED BUOY REPORTS AND ALTIMETRY DATA FROM THIS EVENING AS THE MODEL-GENERATED SWELLS HAVE DAMPENED OUT. THE GUIDANCE BRINGS 8-9 FT IN E SWELLS OVER THE S PART TONIGHT AND THU...WHICH IS A POSSIBILITY AS THE GRADIENT INCREASES. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER COBB