000 AGXX40 KNHC 050805 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 405 AM EDT FRI APR 5 2013 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... DEEP CONVECTION OCCURRING OUT AHEAD OF COLD FRONT HAS IGNITED AGAIN TONIGHT ALONG AND AHEAD OF MID LEVEL PERTURBATION MOVING THROUGH E SIDE OF UPPER TROUGH...WITH MILD DIFFLUENCE AND SPEED DIVERGENCE LEADING TO SUSTAINED DEEP CONVECTION MARCHING NE ACROSS SW FLORIDA COASTAL WATERS AND S PORTIONS OF THE PENINSULA. COLD FRONT LOOKS TO EXTEND FROM WEAK LOW PRES ACROSS FL PANHANDLE SSW TO W PORTIONS OF YUCATAN PENINSULA. TSTMS PREVAIL WITHIN LINES OF CONVECTION MOVING ACROSS S FLORIDA AND SE GULF...WITH WIDESPREAD AND FREQUENT LIGHTNING DETECTED. BROAD FIELD OF NW-N WINDS 20-25 KT TODAY BUILT SEAS 8-10 FT BEHIND FRONT...WITH BUOY 42055 BRIEFLY RISING TO 10 FT AT 01Z. SEAS THROUGH CENTRAL GULF BEHIND FRONT WERE GENERALLY 1-2 FT ABOVE WW3. UPPER TROUGH FORECAST TO SWEEP ACROSS NE AND E GULF TODAY WITH DYNAMICS IN PLACE ALONG AND AHEAD OF FRONT FOR SEVERE OR NEAR SEVERE TSTMS. MARINERS SHOULD THUS BE ADVISED THAT HAZARDOUS WIND AND SEAS CONDITIONS CAN BE EXPECTED WITH THIS ACTIVITY INTO FRI. FRONT EXPECTED TO MOVE SE TODAY AND ACROSS EXTREME SE PORTIONS AND S FLORIDA LATE THIS MORNING INTO THIS AFTERNOON AND THEN NW CUBA TO SE FLORIDA COASTAL WATERS BY 00Z THIS EVENING. HIGH PRES WILL BUILD ACROSS THE AREA IN THE WAKE OF THE FRONT THEN SHIFT EASTWARD SAT AND SUN AS LOW PRES DEEPENS OVER THE CENTRAL UNITED STATES...ALLOWING FOR SOUTHERLY RETURN FLOW TO INCREASE OVER THE WESTERN GULF THROUGH TUE. FOR THE UPCOMING FORECAST...DO NOT INTEND TO MAKE MUCH CHANGES AND WILL BLEND IN SMALL PORTION OF CURRENT GFS AND ECMWF RUNS THROUGH 36 HOURS. SW N ATLC S OF 31N W OF 55W... DEEP CONVECTION MENTIONED ABOVE IS SHIFTING NE OFF THE SE COAST OF FLORIDA AND INTO THE OFFSHORE WATERS ATTM. THIS TREND EXPECTED TO CONTINUE THROUGH THIS EVENING AS TROUGH EXTENDING INTO GULF OF MEXICO SWEEPS E ACROSS THE FLORIDA PENINSULA TONIGHT AND ACROSS 70W SAT NIGHT. AGAIN...DYNAMICS ARE IN PLACE FOR STRONG TO NEAR SEVERE CONVECTION ALONG AND AHEAD OF THE FRONT AND MARINERS SHOULD BE ALERT. MODELS IN REASONABLE AGREEMENT THROUGH 24 HOURS...WITH GFS THEN FASTER THAN EUROPEAN MODELS DAY 2-4 AS GFS MORE FOCUSED ON CONVECTION AHEAD OF FRONT AND ASSOCIATED TROUGHING/SQUALL LINES...WHILE EUROPEAN MODELS FORECAST SLIGHTLY DEEPER LOW PRES ALONG FRONT AFTER 36 HOURS. I HAVE TRIED TO GO WITH A CONSENSUS WITH THIS PACKAGE LEANING TOWARD THE EUROPEAN SOLUTIONS WHICH ARE IN DECENT AGREEMENT WITH THE ENSEMBLES. EXPECT THE FRONT TO MEANDER OF THE FLORIDA E COAST BY 00Z TONIGHT THROUGH THE STRAITS...REACHING 30N69W TO CENTRAL CUBA BY 00Z SUN THEN 30N60W TO E CENTRAL CUBA BY 00Z MON. S TO SW FLOW AHEAD OF FRONT 20-25 KT EXPECTED TO NARROW ZONE OF 30 KT INDICATED BY GFS...SUGGESTING VERY UNSTABLE CONDITIONS. N TO NE WINDS BEHIND FRONT AND LOW PRES EXPECTED TO DEVELOP WITH INCREASE TO 25-30 KT ACROSS N PORTIONS TONIGHT THROUGH SUN...WITH SLIGHT CHANCE FOR BRIEF GALES IN NW QUAD OF LOW AS IT SHIFTS NE OUT OF AREA TONIGHT THROUGH EARLY SUN. SEAS WILL BUILD 8-11 FT THERE...WHILE S-SW FLOW 20-25 KT AHEAD OF FRONT SHIFTS E ACROSS NE PORTIONS. CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W... THE PRES GRADIENT ACROSS THE CARIBBEAN HAS WEAKENED SLIGHTLY IN THE PAST 24 HOURS AS GULFMEX FRONT SHIFTS SEWD. RECENT SCATTEROMETER PASSES SHOWED 20-25 KT WINDS ACROSS CENTRAL PORTIONS S OF 14.5N WHERE SEAS ARE LIKELY 9-10 FT. A PAIR OF WEAK LLVL PERTURBATIONS...IN THE FORM OF SCREAMING EAGLES...ARE MOVING W ACROSS THE NE CARIBBEAN WITH THE SECOND APPROACHING THE LEEWARDS. LOOK FOR THESE FEATURES TO MOVE W-NW NEXT 24 HOURS AND WEAKEN...BUT WITH SHALLOW CONVECTION AND SQUALLS...MOSTLY WITH TROUGH APPROACHING LEEWARDS. AS THE FRONT MOVES INTO NW CARIB EARLY THIS EVENING AND THEN STALLS ACROSS NW PORTIONS E CENTRAL CUBA TO FAR N NICARAGUA BY SUN NIGHT...MODERATE TO FRESH E TRADE WINDS WILL PREVAIL ACROSS THE REGION. BUILDING SEAS SHOULD BE EXPECTED ACROSS N PORTIONS OF TROPICAL N ATLC WATERS...BEHIND TROUGH APPROACHING LEEWARDS NEXT 24-36 HOURS...BUILDING TO 8-9 FT THIS AFTERNOON AND EVENING. WARNINGS... GULF OF MEXICO... .NONE. CARIBBEAN SEA AND TROPICAL N ATLC... .NONE. SW N ATLC... .NONE. EFFECTIVE 20 MARCH 2013...TAFB GRIDDED MARINE FORECASTS FOR 10-M WINDS...10-M WIND GUSTS...SIGNIFICANT WAVE HEIGHTS AND HAZARDS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) ON AN EXPERIMENTAL BASIS AT: HTTP://PREVIEW.WEATHER.GOV/GRAPHICAL ADDITIONAL INFORMATION IS AVAILABLE AT WWW.NWS.NOAA.GOV/OM/NOTIFICATION/PNS13OFFSHORE_HIGHSEAS.HTM NOTE...GRIDDED MARINE FORECASTS AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE WILL BE DISCONTINUED ONCE THE "OCEANIC" VIEW IS ADDED TO THE EXPERIMENTAL NDFD GRAPHICAL INTERFACE. $$ FORECASTER STRIPLING