000 AGXX40 KNHC 081831 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 235 PM EDT SUN JUL 08 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... AN E TO W RIDGE EXTENDS ACROSS THE NORTHERN GULF ALONG 28N WITH A 1020 MB SURFACE HIGH OVER THE FL BIG BEND. THE NORTHERN END OF A TROPICAL WAVE HAS MOVED W INTO THE FAR EASTERN BAY OF CAMPECHE S OF 22N. EXPECT THIS WAVE TO CONTINUE W THROUGH THE BAY OF CAMPECHE THROUGH MON WITH THE MAIN IMPACT BEING AN INCREASED CHANCE OF SHOWERS AND TSTMS. A SECOND TROPICAL WAVE WILL MOVE THROUGH THE STRAITS OF FL ON THU AND WEAKEN OVER THE SE GULF ON FRI. ITS PRIMARY IMPACT ON THE SENSIBLE WX WILL ALSO SIMPLY BE AN INCREASE IN THE CHANCE OF SHOWERS AND TSTMS OTHERWISE...THE RIDGE WILL DOMINATE THE GULF WITH CONVECTION PRIMARILY FOUND IN THE N CENTRAL AND SE GULF COASTS AND IN THE BAY OF CAMPECHE OVER THE FORECAST PERIOD. MODEL DIFFERENCES COME INTO PLAY WITH THE AMPLITUDE OF THE WEAK DEEP LAYER TROUGHING OVER THE CENTRAL GULF STATES ON THU. THE 12Z UKMET APPEARS TO BE A STRONG OUTLIER WITH THE SFC REFLECTION OF THE TROUGH...CARRYING A WEAK COLD FRONT THROUGH LOUISIANA FRI WITH FRESH W FLOW BRIEFLY BUILDING BEHIND IT FRI MORNING. THE 12Z GFS AND 00Z ECMWF DO NOT CARRY THE BOUNDARY INTO THE GULF AND KEEP WINDS LESS THAN 10 KT OVER THE N CENTRAL GULF FRI. THE GFS SOLUTION LOOKS REASONABLE HERE AND DOES NOT STRAY FROM THE PREVIOUS FORECAST MUCH ELSEWHERE. THE OFFICIAL FORECAST BLENDS THE 12Z GFS WITH CONTINUITY THIS AFTERNOON THROUGH FRI. SW N ATLC S OF 31N W OF 55W... A RIDGE EXTENDS E TO W ALONG 28N THIS AFTERNOON WITH GUIDANCE SUGGESTING THE RIDGE WILL MEANDER ALONG ROUGHLY THIS POSITION THROUGH MON BEFORE LIFTING INTO FAR NORTHERN WATERS TUE THROUGH FRI. SW WINDS N OF THE RIDGE WILL CONTINUE AT 10-15 KT...WHILE ELY WINDS S OF 23N WILL BE MOSTLY IN THE 15-20 KT RANGE THROUGH WED EXCEPT MOSTLY 20 KT ACROSS OFFSHORE ZONE AMZ123. FRESH NE WINDS JUST N OF HAITI AND IN THE ATLC APPROACHES TO THE WINDWARD PASSAGE OBSERVED BY THE 1502 UTC ASCAT PASS WERE INITIALED SLIGHTLY WEAKER BY THE 12Z GFS. THE OFFICIAL FORECAST REFLECTS THE SLIGHTLY STRONGER OBSERVED WINDS COMPARED TO THE GFS. MID LEVEL ENERGY SHED YESTERDAY FROM THE NORTH END OF THE TROPICAL WAVE CURRENTLY OVER THE BAY OF CAMPECHE CONTINUES TO BE THE FOCUS OF SCATTERED TSTMS TO THE WESTERN BAHAMAS AND SOUTHERN FL. THIS ENERGY SHOULD REMAIN BETWEEN SE FL AND THE BAHAMAS THOUGH MON BEFORE LIFTING NW ACROSS FL MON EVE. THIS LINGERING ENERGY ACCOMPANIED BY INCREASING PRECIPITABLE WATER VALUES SHOULD ALLOW THE CHANCE OF SCATTERED SHOWERS AND TSTMS TO CONTINUE HERE THROUGH TUE. ANOTHER TROPICAL WAVE WILL MOVE W TO ALONG 65W EARLY MON AND CONTINUE W THROUGH THE SE BAHAMAS TUE...REACHING THE WESTERN BAHAMAS WED AND THE STRAITS OF FL THU. THIS WAVE APPEARS MUCH DRIER THAN THE WAVE THAT IS PASSING INTO THE BAY OF CAMPECHE ATTM. HOWEVER...IT DOES HAVE MORE TSTMS ACTIVITY ASSOCIATED WITH IT TODAY THAN THIS TIME YESTERDAY AND THIS NEXT WAVE WILL BE MOVING INTO A POOL OF 1.75 TO 2.00 INCH PRECIPITABLE WATER VALUES BY TUE AS IT APPROACHES THE BAHAMAS. IT IS EXPECTED TO BRING AN INCREASED CHANCE OF SCATTERED SHOWERS AND ISOLATED TSTMS TO THE BAHAMAS AND SOUTHERN FLORIDA TUE THROUGH THU. OVERALL...THE NUMERICAL GUIDANCE IS IN REASONABLY GOOD AGREEMENT. THE OFFICIAL FORECAST BLENDS THE 12Z GFS WITH CONTINUITY THIS AFTERNOON THROUGH FRI. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... ELY TRADES ARE AT 25-30 KT ACROSS MUCH OF THE CARIBBEAN S OF 14N BETWEEN 74W AND 79W ACCORDING TO THE 1504 UTC ASCAT PASS. THE STRONGEST TRADES HAVE SHIFTED WESTWARD COMPARED TO YESTERDAY... FILLING IN BEHIND THE TROPICAL WAVE THAT HAS PASSED THROUGH THE YUCATAN PENINSULA SINCE THAT TIME. THE SAME PASS SHOWED FRESH WINDS IN THE GULF OF HONDURAS SHRINKING IN AREA AS THE PRES GRADIENT RELAXES BETWEEN THE TROPICAL WAVE TO THE W AND HIGH PRES TO THE NE. THE PRES GRADIENT SHOULD RELAX A BIT OVER THE CENTRAL CARIBBEAN TONIGHT UNTIL LATE TUE WHEN RIDGING SHOULD BUILD BEHIND THE TROPICAL WAVE PASSING THROUGH THE GREATER ANTILLES. THIS WAVE IS EXPECTED TO TRACK WESTWARD N OF 15N. IT SHOULD LIE OVER THE USVI MON MORNING...MOVE THROUGH HAITI TUE MORNING... REACH CENTRAL CUBA BY THU MORNING AND THE YUCATAN CHANNEL BY FRI MORNING. THE 12Z GFS AND 00Z ECMWF ARE IN REASONABLE AGREEMENT ON THIS TIMING. FRESH TRADES SHOULD BUILD OVER THE TROPICAL N ATLC IN THE WAKE OF THIS TROPICAL WAVE LATE MON AND TUE...DIMINISHING WED. THERE WAS NO REASON TO STRAY FROM THE PREVIOUS FORECAST THINKING WHICH MOSTLY LOOKS LIKE THE 12Z GFS. THE OFFICIAL FORECAST BLENDS THE 12Z GFS WITH CONTINUITY THIS AFTERNOON THROUGH FRI. NOTE...GRIDDED MARINE OUTPUT IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .NONE. CARIBBEAN SEA... .NONE. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER