000 AGXX40 KNHC 210834 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE MIAMI FL 430 AM EDT TUE JUL 21 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... WEAK FRONTAL BOUNDARY HAS BEEN PUSHED S INTO THE NE GULF...SUPPORTED BY SHARP AND NARROW UPPER TROUGH ACROSS THE ERN U.S. DEEP MOISTURE HAS BEEN SWEPT AWAY TO THE NE AND OUT OF THE REGION...WITH SOME MODEST MOISTURE NOW ALONG SRN PERIPHERY OF UPPER TROUGH IN SE GULF. THE WEAK SURFACE HIGH WAS CENTERED ACROSS THE NE GULF...AND IS COMBINING WITH LOW PRES IN THE CENTRAL PLAINS TO INDUCE SLY RETURN FLOW ACROSS THE NW GULF AND TEXAS COAST. NLY AND MILDLY DIFFLUENT UPPER LEVEL FLOW ON THE BACK SIDE OF THE UPPER TROUGH WAS ENHANCING SCATTERED CONVECTION ACROSS SE TEXAS THAT HAS SINCE DIMINISHED IN INTENSITY..BUT PERSISTS ALONG THE TEXAS AND SW LOUISIANA COASTS OUT TO 90 NM FROM SHORE. ANOTHER S/W FORECAST TO DROP INTO BACK OF TROUGH WILL FORCE A NARROW TROUGH FARTHER S INTO THE SE GULF AND SW FLORIDA AND MAINTAIN SOME DIFFLUENCE ACROSS THE TEXAS COAST FOR ACTIVE AFTERNOON WEATHER THERE. OTHERWISE THE GULF REMAINS NEARLY FREE OF SIGNIFICANT CONVECTION. LIGHT TO MODERATE WINDS PERSIST OVERALL ACROSS THE GULF...WITH S-SE WINDS OF 15 KT ACROSS THE FAR NW INCREASING TO 15-20 KT ACROSS THE TEXAS COASTAL WATERS AND COASTAL BUOYS NOW SHOWING 4-6 FT SEAS. LITTLE CHANGE IN THE PATTERN IS EXPECTED THROUGH WEDNESDAY...WHEN THE PRES GRADIENT WEAKENS...LEAVING LIGHT WINDS ACROSS THE NRN GULF AND MODERATE WINDS ACROSS THE SRN GULF AS WEAKENED N PORTIONS OF TROPICAL WAVES MOVE THROUGH THE WRN CARIB AND ACROSS THE YUCATAN. CARIBBEAN... A TROPICAL WAVE ALONG 81W CONTINUES TO BECOME STRETCHED AND ELONGATED N-NE TO S-SW...ALL THE WHILE WEAKENING...WITH THE BEST ENERGY AND MOISTURE MOVING NW INTO THE BAHAMAS AND SW N ATLC. THE SRN PORTION OF THIS WAVE HOWEVER REMAINS QUITE MOIST AND IS INTERACTING WITH THE EPAC MONSOON CIRCULATION TO PRODUCE SCATTERED TO NUMEROUS DEEP CONVECTION ACROSS THE EPAC E OF 87W...ACROSS CENTRAL AMERICA AND INTO THE FAR SW CARIB. THIS SRN PORTION OF THE WAVE IS LIKELY A BIT OUT AHEAD OF THE NRN PORTION BUT A FEW DEGREES...AND WILL REMAIN ACTIVE CONVECTIVELY ACROSS THE AREA THROUGH TODAY BEFORE ASSOCIATED WEATHER SHIFTS W AND SW WED INTO THU. SHARP CYCLONIC TURNING WAS NOTED BY AN EVENING QUIKSCAT PASS ACROSS THE WRN CARIB...YIELDING WINDS GENERALLY 15 KT OR LESS AND ALLOWING FOR SEAS TO CONTINUE TO SUBSIDE W OF 75W. SOME MODEST INCREASE IN WINDS WILL SPREAD W ACROSS THE WRN CARIB TODAY AND TONIGHT BEHIND THIS TROPICAL WAVE...INCREASING TO 15-20 KT WITH SEAS REMAINING 5-6 FT. FRESH TO STRONG WINDS AND BUILDING SEAS CURRENTLY DOMINATING THE ERN CARIB ARE EXPECTED TO SPREAD ACROSS THE ENTIRE BASIN WED EVENING THROUGH FRIDAY TO BRING A RETURN TO 20-25 KT WINDS AND 8-10 FT SEAS TO THE W AND SW CARIB...WITH 30 KT WINDS AND SEAS TO 12 FT POSSIBLE OFF THE COAST OF COLOMBIA. CURRENTLY...A SECOND TROPICAL WAVE IS MOVING ACROSS THE EASTERN CARIBBEAN THIS MORNING. THIS WAVE TILTED SLIGHTLY NW TO SE BROUGHT VERY SQUALLY WEATHER TO THE LESSER ANTILLES AND EXTREME ERN CARIB THIS AFTERNOON AND EVENING AND INCREASING WINDS AND SEAS...WITH AN EVENING QUIKSCAT PASS SHOWING 20-25 KT WINDS WITH A SMALL AREA OF 25-30 KT ACROSS THE ANTIGUA-ST MARTEEN-ST KITTS AREA. THE SAN JUAN PR UPPER AIR SOUNDING SHOWED 45 KT WINDS AT JUST BELOW 10K FT AT 00Z...INDICATING THE ENERGETICS AND LOWER TROPOSPHERIC JET ASSOCIATED WITH THIS WAVE...WHICH LIKELY EXTENDS FROM NEAR THE TURKS AND CAICOS ISLANDS E-SE ACROSS THE NE CARIB ISLANDS TO NEAR 55W. THE WAVE AXIS WAS LIKELY SOMEWHERE INVOF 64/65W WITH THE VORTEX THAT WE HAVE BEEN MONITORING THE PAST SEVERAL DAYS SUGGESTED BY STLT IMAGERY NEAR 15.5N 65W...AND BEING STRONGLY SHEARED BY W-NW UPPER LEVEL FLOW. THESE STRONG LOW LEVEL WINDS...AND AN ELONGATED WIND SURGE OF 20-25 KT WINDS WITH SMALL POCKETS OF HIGHER WINDS...WILL DOMINATE THE NE CARIB AND ADJACENT ATLC TODAY BEFORE SHIFTING MW INTO THE BAHAMAS TONIGHT. THIS WILL MAINTAIN THE VERY SQUALLY CONDITIONS DURING THE NEXT 24 HOURS...AND BUILD SEAS INSIDE THE CARIB AND N OF 16N TO 9-11 FT...WITH HIGHEST WINDS AND SEAS LIKELY JUST S OF THE MONA PASSAGE AND HISPANIOLA. BUOY 42060 W OF GUADELOUPE HAS ALREADY BUILT TO 9 FT...WHILE THE NEW BUOY OFF THE S COAST OF PUERTO RICO WAS QUICKLY APPROACHING 6 FT EARLY THIS MORNING. AS THE WAVE CONTINUES TO MOVE W-NW TONIGHT INTO WED...WINDS WILL INCREASE S OF 16N TO 20-25 KT AND SPREAD W INTO THE CENTRAL CARIB... BUILDING SEAS IN A MORE TYPICAL AREAL FASHION. ATLANTIC S OF 31N W OF 55W... THE TROPICAL WAVE CURRENTLY IN THE ERN CARIB WILL MAINTAIN FRESH TO STRONG E-SE TRADES ACROSS N PORTIONS OF THIS AREA THROUGH TONIGHT...FOLLOWED BY ANOTHER LOWER LAT WIND SURGE ASSOCIATE WITH THE NEXT BENIGN TROPICAL WAVE ALONG 50W...MOVING THROUGH THE AREA WED AND WED NIGHT. TWO STRONG WIND SURGES HAS RECENTLY MOVED ACROSS AND N OF THE LESSER ANTILLES AND THEN MORE NWLY INTO THE SW N ATLC E AND NE OF THE BAHAMAS...WITH TRAILING MOISTURE AND LOW LEVEL WIND FORCING CONTINUING TO INTERACT WITH A NEGATIVELY TILTED UPPER LOW JUST E OF THE BAHAMAS...TO MAINTAIN VERY ACTIVE AND SQUALLY WEATHER. THE UPPER TROUGH ACROSS THE ERN U.S. WILL COMBINE WITH A CONTINUOUS FEED OF TROPICAL MOISTURE SUPPLIED BY THE MID TROPOSPHERIC JET MOVING ACROSS THE NE CARIB AND INTO THE BAHAMAS TO PRODUCE VERY ACTIVE WEATHER N OF 18N AND W OF 68W FOR THE NEXT FEW DAYS. THE ASSOCIATED LOW LEVEL WIND SURGE HAS PUSHED CONVECTION ALL THE WAY INTO S FLORIDA...AND N OF 30N DURING THE PAST 6 HOURS...AND WILL SPREAD SE WINDS 20-25 KT WITH SMALL AREAS TO 30 KT...AND SEAS OF 8-9 FT INTO THE SE BAHAMAS BY THIS AFTERNOON AND THEN N AND NW TO THE CENTRAL BAHAMAS AND ADJACENT ATLC WATERS BY WED AFTERNOON. ALTHOUGH THE MAJORITY OF ENERGY AND MOMENTUM WILL TRANSLATE NWWD...A MODEST INCREASE IN WINDS AND SEAS WILL BE SEEN INTO FAR SRN FLORIDA...THE KEYS...AND THE STRAITS OF FLORIDA DURING THE NEXT 48 HOURS...WITH VERY ROUGH AND STEEP SEAS IN THE LEE OF THE SRN BAHAMAS DUE TO STRONG SELY WINDS. WARNINGS ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. $$ $$ FORECASTER STRIPLING