000 AGXX40 KNHC 191817 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 117 PM EST TUE DEC 19 2006 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... HIGH PRES CENTERED OVER MISSOURI WITH A SURFACE RIDGE EXTENDING SE INTO THE W ATLC WATERS CONTINUES TO PRODUCE MAINLY NE/E FLOW ACROSS THE GULF. A NARROW BELT OF 15-20 KT WINDS EXTENDS FROM THE STRAITS OF FLORIDA NW TOWARDS THE LOUISIANA COAST...AND A RESULTANT SHEAR AXIS OVER THE NW GULF HAS PRODUCED A MINIATURE- SCALE LOW CENTER JUST E OF BROWNSVILLE TX. THE HIGH BUILDS SE AND INCREASES THE GRADIENT OVER THE E GULF WED/THU...THEN BACKS OFF AFTER A WEAK COLD FRONT MOVES OFF THE TEXAS COAST WED NIGHT/ THU MORNING. ALL MODELS HAVE COME INTO AGREEMENT WITH THE TIMING OF FRONT. HOWEVER...THERE ARE STILL SIGNIFICANT DIFFERENCES REGARDING THE FATE OF THE FRONT ONCE IT MOVES INTO THE GULF... CENTERING ON THE BEHAVIOR OF THE CLOSED LOW OVER THE DESERT SW. MOST MODELS FAVOR A SLOW EWD MOVEMENT OR EVEN STALL THE BOUNDARY JUST OFFSHORE FOR A DAY OR TWO. EVERY MODEL EXCEPT THE NOGAPS THEN DEVELOPS AN AREA OF LOW PRES ALONG THE FRONT NEAR THE LOWER RIO GRANDE VALLEY ON SAT THEN LIFT N ON SUN WITH A TRAILING COLD FRONT. THE GFS...ALTHOUGH IT MAY BE SUFFERING CONVECTIVE FEEDBACK ISSUES...INCREASES WINDS NEAR THE LOW AND BEHIND THE FRONT TO 40 KT. ALTHOUGH THE GFS ENSEMBLE MEAN IS COMPARATIVELY (AND LOGICALLY) SUPPRESSED...IT DOES INDICATE UP TO A 50% PROBABILITY OF GALE CONDITIONS OVER THE W GULF ON SUN. I WILL THEREFORE MENTION GALE CONDITIONS FOR SUN W OF 94W OVER THE NW AND SW GULF ZONES. THERE IS A POSSIBILITY THAT THESE CONDITIONS COULD BEGIN SAT NIGHT...BUT THERE IS STILL GREAT UNCERTAINTY IN TIMING OF THE FRONT SO WILL MONITOR OVER THE COMING DAYS. SW N ATLC... RIDGE OF HIGH PRES ALONG 31N IS KEEPING A STEADY FETCH OF 15-20 KT EASTERLIES S OF 25N ACROSS THE BAHAMAS TO THE STRAITS OF FLORIDA. A COLD FRONT CURRENTLY FROM NORTH CAROLINA EWD INTO THE ATLC WILL DROP S AND ENTER THE AREA EARLY WED MORNING WITH A QUICKLY INCREASING PRES GRADIENT COVERING THE ENTIRE ZONE BY AFTERNOON...AND SUBSEQUENTLY WINDS INCREASING TO 20-25 KT OVER MUCH OF THE AREA. THE HIGHEST WINDS DON'T LAST FOR TOO LONG SO IT DOES NOT APPEAR THAT MAXIMUM SEAS WILL BE ACHIEVED...ALTHOUGH THERE WILL STILL BE SOME NE SWELL WHICH PROPAGATES TOWARDS THE FLORIDA COAST AND BAHAMAS. THE POST-FRONTAL HIGH WEAKENS A BIT ON THU WITH WINDS DYING DOWN AND STRONGEST 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. AN AREA OF LOW PRES/COLD FRONT MOVE ACROSS THE SE U.S. ON SUN WITH OFFSHORE WINDS VEERING TO SW JUST AHEAD. AT THIS POINT THE FRONT ITSELF DOES NOT APPEAR TO MOVE OFFSHORE UNTIL SUN NIGHT...SO WILL HOLD OFF MENTIONING ANY WIND SHIFTS CONSIDERING THE GENERAL RUN-TO-RUN MODEL TIMING DIFFERENCES. CARIBBEAN AND TROPICAL ATLC... MODERATE TO FRESH TRADES CONTINUE WITH NO REAL SIGNIFICANT CHANGES THROUGH SUN. WITH HIGH PRES STRENGTHENING TO THE N ON WED...IT IS LIKELY THAT WINDS MAY INCREASE SLIGHTLY OVER THE CENTRAL CARIBBEAN WED NIGHT AND LAST THROUGH SUN (POSSIBLY AS HIGH AS 30 KT ALONG THE IMMEDIATE COLOMBIAN COAST). WINDS ALSO INCREASE SLIGHTLY OVER THE N PART OF THE TROPICAL ATLC WATERS THU NIGHT THROUGH SUN AS THE ATLC HIGH SHIFTS E. AS FAR AS THE WAVE SITUATION E OF THE ISLANDS...THE WAVEWATCH IS FINALLY COMING MORE IN LINE WITH OBSERVED BUOY REPORTS PROBABLY AS THE MODEL-GENERATED SWELLS DAMPEN OUT. THE GUIDANCE STILL BRINGS 8-9 FT IN E SWELLS OVER THE S PART WED NIGHT INTO THU...WHICH IS A POSSIBILITY AS THE GRADIENT INCREASES...BUT WILL STILL FAVOR FNMOC GUIDANCE SINCE I AM SKEPTICAL OF HOW THE WAVEWATCH HAS BEEN HANDLING SWELLS RECENTLY. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER BERG