000 AGXX40 KNHC 060810 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 410 AM EDT THU AUG 06 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... A WEAK FRONTAL TROUGH EVIDENT OVER THE EXTREME NE WATERS ATTM HAS BLOWN UP WITH TSTMS FROM BILOXI BAY TO 91W...WHICH ARE BEING NUDGED SWD BY NLY FLOW ALOFT OCCURRING ON BACK SIDE OF SHARP UPPER TROUGH. NUMEROUS WIDESPREAD LIGHTNING STRIKES EVIDENT PER LIGHTNING DETECTION SYSTEM...INDICATING CONTINUED INTENSIFICATION OR GROWTH OF THESE TSTMS. THIS TSTM ACTIVITY WILL LIKELY SHIFT SW AND GRADUALLY DIMINISH...BEING FORCED BY UPPER FLOW...WITH MORE ISOLATED TSTMS PERSISTING ALONG FRONTAL TROUGH ACROSS NE GULF REMAINDER OF THE NIGHT. THE NRN PORTION OF A TROPICAL WAVE IN THE FORM OF A LOW LEVEL TROUGH HAS PUSHED WNW INTO THE FAR SE GULF AND SLOWED FORWARD MOTION DUE TO DIFFLUENT LLVL FLOW JUST UPSTREAM. THIS MOISTURE WILL LINGER ACROSS THE SE THIRD OF THE GULF AND SLOWLY SHIFT W AND NW NEXT FEW DAYS...ALLOWING FOR SCATTERED SHOWERS AND ISOLATED TSTMS. BETWEEN THESE TWO FEATURES LIES AN ELONGATED AREA OF AMPLE LLVL MOISTURE WHICH IS YIELDING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS...WITH UPPER TROUGH ACROSS NRN GULF PROVIDING THE SYNOPTIC LIFT. THIS WILL REMAIN ACTIVE THROUGHOUT THE NEXT 24 HOURS. WIND AND WAVE-WISE...THE ATLC RIDGE WILL WEAKEN ACROSS WRN PERIPHERY NEXT 48 HOURS AS E COAST UPPER TROUGH AND FRONTAL SYSTEM NUDGE THE UPSTREAM HIGH ENE. THIS WILL CAUSE THE WEAK RIDGING ACROSS THE NRN GULF TO DRIFT N AND INLAND...AND ALLOW FOR A MORE PROGRESSIVE ELY FLOW ACROSS THE FAR SRN GULF BY THE WEEKEND...AND A MODEST INCREASE IN SELY FLOW ACROSS THE S CENTRAL AND WRN HALF OF THE GULF. TRANQUIL SEAS OF RECENT DAYS ACROSS THE N HALF WILL INCREASE SLIGHTLY...WITH WINDS INCREASING 15-20 KT SAT EVENING ACROSS THE SW GULF AND SPREADING ACROSS THE W AND NW PORTIONS SUN. SEAS IN TURN WILL INCREASE TO 4-5 FT DURING THE WEEKEND ALL BUT NE PORTIONS...POSSIBLY WITH PERIODS OF 6 FT SEAS ACROSS THE YUCATAN CHANNEL AND OFF THE NW COAST OF THE YUCATAN PENINSULA...WHERE THE TYPICAL EVENING BACKING OF WINDS WILL CONTINUE TO OCCUR. E TO SE WINDS AROUND 15 KT ACROSS THE STRAITS OF FLORIDA ARE LIKELY TO INCREASE TO 20 KT FOR THE WEEKEND AS THE LOWER LAT FLOW BECOMES MORE ELY. TROPICAL ATLC AND CARIBBEAN SEA... A TROPICAL WAVE ACROSS THE WRN CARIB IS PROVIDING INCREASED MOISTURE FOR SCATTERED SHOWERS AND ISOLATED TSTMS W OF 80W THIS MORNING...AND WILL CONTINUE TO BE ENHANCED BY THE WRN END OF AN E TO W TUTT SEGMENT. DRY SAHARAN AIR IS BEHIND THIS WAVE AND DOMINATING THE CENTRAL CARIBBEAN...WHERE A SOMEWHAT TYPICALLY BROAD AREA OF 20-25 KT WINDS ARE OCCURRING BETWEEN 70W AND 80W...WITH PEAK WINDS AND SEAS OFF THE COLOMBIA COAST...WHERE SEAS ARE ESTIMATED NEAR 11 FT. A SECOND TROPICAL WAVE PASSING S OF THE VIRGIN ISLANDS ATTM WILL CONTINUE W TODAY AND TONIGHT AND BRING MODEST MOISTURE ACROSS MOST OF THE ERN CARIBBEAN FOR SCATTERED SHOWERS AND TSTMS. BEHIND THE WAVE...ANOTHER WIND SURGE OF 20-25 KT WILL SPREAD FROM CURRENT LOCATION OF 45W-55W...AND W-SW ACROSS THE TROPICAL ATLC LATE THIS MORNING AND INTO THE ERN CARIB TONIGHT INTO SAT. THIS WILL RAISE SEAS ACROSS BOTH SIDES OF THE LESSER ANTILLES TO 7-8 FT ATLC WATERS TONIGHT...AND 6-7 FT INSIDE THE CARIBBEAN LATE SAT INTO SUN. SOME SQUALLY WEATHER IS LIKELY ON THE BACK SIDE OF THIS SECOND TROPICAL WAVE AS A BROAD 35-40 KT MID LEVEL JET MOVES INTO THE E AND EXTREME NE CARIB TODAY. WITH SAHARAN AIR ACCOMPANYING THIS WIND MAX...LOOK FOR THESE SQUALLS CAPABLE OF PRODUCING WIND GUSTS IN EXCESS OF 40 KT...PARTICULARLY ACROSS THE EXTREME NE CARIB AND ADJACENT ATLC TODAY. LLVL WINDS ASSOCIATED WITH THIS WAVE WILL REACH THE WRN HALF OF THE CARIB SAT...EXPANDING THE 20-25 KT WIND FIELD AS FAR N AS JUST OFFSHORE OF BARAHONA DOMINICAN REPUBLIC...AND W TO JUST OFFSHORE OF THE CENTRAL AMERICAN COASTS. WINDS ALONG COASTAL COLOMBIA WILL RETURN TO 30 KT SAT...AND COULD APPROACH NEAR GALE FORCE BRIEFLY SAT AND SAT NIGHT...WITH SEAS BUILDING 12-13 FT THERE. SW ATLC W OF 55W... ESE-SE WINDS OF 15 TO 20 KT CONTINUE ACROSS THE FLORIDA STRAITS AND OPEN WATERS UPSTREAM TO 76W...BEHIND THE NORTHERN EXTENSION OF THE TROPICAL WAVE IN THE SE GULF. ANOTHER NRN PORTION OF THE NEXT TROPICAL WAVE ACROSS THE ERN CARIB IS ALONG ABOUT 70W ATTM AND IS BRINGING A BROAD AREA OF 20+ KT WINDS WITH IT AS IT MOVES WNW 15-20 KT THIS MORNING. AN ELONGATED UPPER LOW STRETCHING NWD FROM PUERTO RICO HAS ENHANCED CONVECTION ASSOCIATED WITH THIS WAVE DURING THE PAST 24 HOURS...BUT THE LLVL TROUGH IS NOW MOVING UNDER THE BACKSIDE NLY FLOW OF THIS UPPER TROUGH...AND INTO UPPER CONVERGENCE...WHICH IS NOT CONDUCIVE FOR WIDESPREAD DEEP CVNTN. HOWEVER...SHOWERS AND GUSTY WINDS IN EXCESS OF 25 KT WILL ACCOMPANY THIS LLVL TROUGH THROUGH THE SRN HALF OF THE BAHAMAS TODAY...AND NE FOR A SEVERAL HUNDRED MILES...AND THEN REACH THE NW BAHAMAS FRIDAY EVENING AND NIGHT. THE LLVL FLOW IS MUCH WEAKER FARTHER UPSTREAM ACROSS THE NW BAHAMAS AND BEYOND... AND THIS TROUGH WILL BOTH SLOW DOWN...AND LOOSE ITS PUNCH IN TERMS OF WIND SPEED AND ASSOCIATED WEATHER LATE FRI AND SAT. THIS WILL HOWEVER...MAINTAIN 20 KT WINDS IN THE CORRIDOR BETWEEN THE BAHAMAS AND CUBA/HISPANIOLA...AND MAINTAIN SEAS 5-7 FT THERE. AS THE ATLC RIDGE WEAKENS SLIGHTLY AND SHIFTS N OVER THE WEEKEND...ELY TRADES WILL RETURN TO LATS S OF 25N...BECOMING ESE ACROSS SRN FLORIDA AND THROUGH THE FLORIDA STRAITS. ELY TRADE WIND SWELL WILL MAINTAIN SEAS 5-7 FT ACROSS THE ATLC S OF 23N THROUGH THE WEEKEND. LOOK FOR ACTIVE WEATHER TO PERSIST ACROSS THE OPEN ATLC E OF 68W THROUGH FRIDAY AS THE UPPER TROUGH CONTINUES TO ENHANCE APPROACHING TROPICAL WAVE RELATED MOISTURE. WARNINGS ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. $$ FORECASTER STRIPLING