000 AGXX40 KNHC 291844 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 245 PM EDT SUN APR 29 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... THERE IS STILL A CONSIDERABLE AMOUNT OF UNCERTAINTY IN THE DETAILS OF THE EVOLUTION OF THE MID LEVEL LOW CURRENTLY NEAR THE FLORIDA KEYS. SURFACE OBSERVATIONS REMAIN EASTERLY ON BOTH SIDE OF THE FLORIDA STRAITS...WITH NO HINT OF A SURFACE LOW DEVELOPING AT THIS TIME. THE ASCAT PASS FROM 1550 UTC SHOWED E-NE WINDS TO 20 KT OFF THE COAST OF NAPLES FLORIDA...WELL N OF FLORIDA BAY. THE 12Z GFS CARRIES 25 KT N-NE WINDS S OF NAPLES AT 1800 UTC TODAY. OBSERVATIONS DO NOT SUPPORT THESE WINDS WHICH APPEARS TO BE A BI-PRODUCT OF CONTINUED CONVECTIVE FEEDBACK ISSUES WITH THE GFS. HOWEVER...THE OBSERVATIONS THIS MORNING AND AFTERNOON FAVOR A STRONGER SOLUTION THAN THE PREVIOUS PACKAGE. ADJUSTMENTS WERE MADE TOWARD THE UKMET SOLUTION WHICH BRINGS THE SYSTEM WESTWARD INTO THE GULF MORE SLOWLY THAN THE GFS AND WAITS TO INCREASE WINDS TO 25 KT UNTIL LATE MON. THE TREND IN THE MODELS HAS BEEN TOWARD MAINTAINING STRONGER RIDGING ALONG THE NORTHERN GULF COASTAL PLAIN AND SOUTHERN PORTION OF THE CENTRAL GULF COAST STATES...MAKING FOR A STRONGER PRES GRADIENT BETWEEN THE SURFACE REFLECTION OF THIS SYSTEM AND THE RIDGE. THE 12Z UKMET IS CONSISTENT WITH ITS 00Z RUN IN ENDING THE 20 KT WINDS AND SEAS AT OR OVER 8 FT IN THE NE GULF AFTER 1800 UTC WED. CARIBBEAN SEA... RIDGING EXTENDS FROM 1032 MB HIGH PRES WELL NE OF THE AREA NEAR 38N34W INTO THE NE CARIBBEAN. THE PRES GRADIENT IS MAINTAINING FRESH TRADES OVER THE CENTRAL AND NE CARIBBEAN THIS AFTERNOON ACCORDING TO OBSERVATIONS AND THE 1412 UTC ASCAT PASS. THIS RIDGE WILL WEAKEN BEGINNING TOMORROW AS A COLD FRONT DIPS SOUTHWARD INTO THE NE PORTION OF THE SW N ATLC FORECAST AREA. BY TUE...THE DOMINANT HIGH PRES WILL SHIFT TO THE WESTERN ATLC AND TRADES WILL DIMINISH A NOTCH IN THE CARIBBEAN. ATLANTIC... OBSERVATIONS THIS MORNING SUPPORTED A STRONGER SOLUTION THAN THE OVERNIGHT PACKAGE WITH THE WINDS FROM SOUTH FLORIDA EASTWARD INTO THE NORTHERN PORTION OF THE TROPICAL N ATLC. THE MORNING PACKAGE WAS ADJUSTED TOWARD OBSERVATIONS INITIALLY WHICH MEANT CARRYING FRESH E-NE WINDS OVER THE LEEWARD ISLANDS AND EASTWARD TO 50W WITH SEAS TO 9 FT IN NE SWELL. WINDS IN THE TROPICAL N ATLC ZONE WILL DIMINISH MON AS THE RIDGE MENTIONED IN THE CARIBBEAN SECTION WEAKENS...WEAKENING THE PRES GRADIENT HERE. THE 12Z GFS CONTINUES TO HAVE CONVECTIVE FEEDBACK ISSUES WITH THE MID-LEVEL LOW NEAR THE FLORIDA KEYS. BOTH THE 12Z AND 06Z GFS STAMPED OUT OVER 6.5 INCHES OF PRECIPITATION BETWEEN 12Z THIS MORNING AND 18Z THIS AFTERNOON E OF THE UPPER KEYS WHICH APPEARS OVERDONE. THIS FEEDBACK CONTINUES TO MAKE ITS FORECAST SUSPECT...BUT THE 00Z ECMWF SOLUTION WAS WEAKER WITH THE WINDS IN THE CENTRAL BAHAMAS THAN THE OBSERVATIONS THIS MORNING. THE UKMET WAS PRIMARILY RELIED ON FOR ITS FORECAST WHICH HAD TRENDED STRONGER WITH THE WINDS HERE COMPARED TO ITS RUN THIS TIME YESTERDAY. THE MODELS HAVE GENERALLY TRENDED TOWARD A MORE STUBBORN RIDGE TO THE NORTH OF THE SURFACE TROUGH REFLECTED FROM THE UPPER LOW OVER THE SE GULF OF MEXICO...ALLOWING FOR MORE WIDESPREAD 25 KT WIND IN THE NORTHERN BAHAMAS TONIGHT THROUGH EARLY TUE. WHILE THIS SYSTEM WILL PASS EASTWARD INTO THE GULF ON TUE...THE PRES GRADIENT WILL REMAIN STRONG ENOUGH OVER THE BAHAMAS TO MAINTAIN FRESH TRADES THROUGH WED NIGHT BECAUSE HIGH PRES WILL BUILD OVER THE WESTERN ATLC BEHIND THE COLD FRONT EXPECTED TO CLIP THE NE PORTION OF THE ATLC FORECAST AREA BEGINNING LATE TOMORROW. THIS FRONT IS EXPECTED TO BE WEAK. NOTE... EFFECTIVE APR 3, 2012 AT 1800 UTC THE OFFSHORE WATERS FORECAST ZONES CHANGED FOR THE CARIBBEAN AND SW N ATLANTIC AND THE GULF OF MEXICO. ISSUANCE TIME FOR THE GULF OF MEXICO OFFSHORE WATERS FORECASTS IS REFERENCED TO THE EASTERN TIME ZONE. FOR DETAILS SEE WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF GRIDDED MARINE OUTPUT IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE (LOWER CASE). GULF OF MEXICO... .NONE. CARIBBEAN SEA... .NONE. ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER