000 AGXX40 KNHC 260639 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 120 AM EST SUN DEC 26 2010 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... A 1004 MB LOW PRES SYSTEM WAS OVER THE NE GULF AT 0000Z. THE GFS AND ECMWF HAVE CONSISTENTLY BEEN WEAKER THAN THIS WITH THE LOW THE PAST FEW RUNS. FOR EXAMPLE...THE 12Z ECMWF FROM THE 23RD SHOWED A 1010 MB LOW IN THE NE GULF FOR 00Z/26. WHILE AN ASCAT PASS FROM 0220Z SHOWED WINDS JUST BELOW GALE FORCE OFF THE COAST OF THE WESTERN FLORIDA PANHANDLE...SEVERAL OBSERVATIONS HAVE REPORTED WINDS AT OR ABOVE GALE SAT EVENING. THE VAST MAJORITY OF THE STATIONS REPORTING GALE HAVE AN ANEMOMETER HEIGHT WELL ABOVE 10 METERS. ONE EXCEPTION WAS BUOY 42040 NEAR 29N88W WHICH REPORTED SUSTAINED 35 KT WINDS AROUND 2300 Z SAT EVENING. A GALE WARNING WAS ISSUED. 0600Z OBSERVATIONS SHOW WINDS CLOSE TO GALE FORCE OVER A WIDESPREAD AREA. THE HSFAT2 VALID 0600Z WILL KEEP THE GALE WARNING UP FOR ANOTHER 3 HOURS. THE LOW WILL RACE NE DURING THAT TIME. THE 00Z GFS AND 12Z ECMWF ARE IN REASONABLE AGREEMENT ON THE TIMING OF THE COLD FRONT S OF THE LOW AND THE TIMING OF THE WINDS DIMINISHING BEHIND IT. THE GFS HAS WINDS TO GALE FORCE ONLY AT 00Z AND THEN DIMINISHES THEM TO LESS THAN GALE FORCE. THE 12Z ECMWF DOES NOT CARRY GALE WINDS AT ALL. RELIED PRIMARILY ON THE MWW3 FOR WAVE HEIGHT GUIDANCE BUT ATTEMPTED TO CORRECT FOR THE BIAS IN THE MWW3 TO HOLD ONTO HIGHER SEAS TOO LONG AFTER THE WINDS HAVE DIMINISHED. THE 00Z GFS AND 12Z ECMWF CONTINUE TO AGREE ON BRINGING THE SE RETURN FLOW IN THE GULF TO 20 KT OVERNIGHT MON NIGHT...BUT THESE MODELS DIVERGE BY TUE WHEN THE GFS BECOMES STRONGER WITH THE WINDS NEARSHORE IN THE NW GULF BECAUSE IT IS FASTER TO CARRY A SOUTHERN STREAM TROUGH EASTWARD THROUGH MEXICO AND THE ECMWF. THE 00Z UKMET CONTINUES TO BE IN BETTER AGREEMENT WITH THE SLOWER ECMWF. PAST EXPERIENCE SHOWS THAT THE UKMET IS GENERALLY GOOD AT HANDLING SUCH A PATTERN AND IT TYPICALLY PREFERS A SLOWER SOUTHERN STREAM SOLUTION IS MUCH A CASE. THEREFORE...LEANED TOWARD THE ECMWF FOR THE FORECAST PAST MON NIGHT. CARIBBEAN AND TROPICAL N ATLC... SURFACE OBSERVATIONS AND THE 0216 Z ASCAT PASS SHOW WIDESPREAD FRESH NE WINDS IN THE EASTERN AND CENTRAL CARIBBEAN TONIGHT WITH STRONG NE WINDS BETWEEN HISPANIOLA AND COLOMBIA. IN ADDITION...N SWELL BEHIND THE ATLC COLD FRONT IS MOVING THROUGH THE N FACING ATLC PASSAGES INTO THE EASTERN CARIBBEAN...KEEPING SEAS CLOSE TO 8 FT IN MUCH OF THE EASTERN CARIBBEAN. THE AFOREMENTIONED COLD FRONT IN THE GULF OF MEXICO SHOULD MOVE THROUGH THE YUCATAN CHANNEL SUN AND STRONG N WINDS ARE EXPECTED TO RAPIDLY FILTER S THROUGH THE WESTERN CARIBBEAN WHILE WINDS DIMINISH OVER THE EASTERN CARIBBEAN. THE 12Z ECMWF AND 00Z GFS CONTINUE TO BE IN GOOD AGREEMENT WITH THE TIMING OF THE FRONT. THE LEADING EDGE OF THE COLD FRONT TRAVELS THROUGH THE WINDWARD PASSAGE MON AND THE MONA AND ANEGADA PASSAGES TUE. WINDS WILL LIKELY BE INTENSIFIED AS THEY FUNNEL THROUGH THE PASSAGES...WITH THE GFS SHOWING WINDS TO JUST BELOW GALE FORCE IN THE MONA PASSAGE AND OFF THE SE COAST OF THE DOMINICAN REPUBLIC BY SUNSET TUE AND OVERNIGHT TUE NIGHT. THE 12Z ECMWF CARRIES A SOLID AREA OF 25 KT WINDS. GIVEN THIS IS A CLIMATOLOGICALY FAVORED LOCATION FOR WINDS TO BE ENHANCED...THE FORECAST HEDGES TOWARD THE STRONGER GFS HERE. SW N ATLC... SW WINDS AT BUOY 41012 NEAR 30N80.5W HAVE ALREADY PICKED UP TO 31 KT AT 0600Z AHEAD OF THE STRONG COLD FRONT PUSHING THROUGH N FLORIDA. AS MENTIONED IN THE GULF OF MEXICO SECTION...THE GFS AND ECMWF HAVE BEEN TOO WEAK WITH THE LOW OVER THE PAST FEW RUNS. IRONICALLY...THE 00Z GFS APPEARS TO BE TOO STRONG WITH THE WINDS AT THIS BUOY LOCATION WHERE IT CARRIES 40 KT WINDS AT 0600 UTC. THE 12Z ECMWF IS IN BETTER AGREEMENT WITH THE BUOY. THESE MODELS ARE IN REASONABLY GOOD AGREEMENT WITH THE TIMING OF THE FRONT AND THE EXPANSE OF THE GALE FORCE WIND FIELD ASSOCIATED WITH IT. BOTH THE 00Z GFS AND THE 12Z ECMWF ARE SHOWING WINDS REACHING 40 KT AHEAD OF THE FRONT SUN. GALE FORCE WINDS ARE FORECAST WITHIN 210 NM EITHER SIDE OF THE FRONT THROUGH MON NIGHT BUT THE GALE WARNING WILL EXPANDED FARTHER W OF THE FRONT ON THE NEXT HSFAT2 ISSUANCE AS THE MODELS HAVE COME INTO BETTER AGREEMENT CARRYING STRONG SHORTWAVE ENERGY INTO THE BACKSIDE OF THE TROUGH THAT HELPS CONTINUE THE GALE W OF THE FRONT LONGER. WARNINGS.. ATLC... .GALE WARNING N OF 27N WITHIN 210 NM OF FRONT SUN THROUGH EARLY MON...AMZ080. CARIBBEAN... .NONE. GULF OF MEXICO... .GALE WARNING N OF 27N E OF 91W...GMZ080. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER