000 AGXX40 KNHC 090804 AAA MIMATS MARINE WEATHER DISCUSSION...UPDATED NWS NATIONAL HURRICANE CENTER MIAMI FL 315 AM EDT THU JUN 09 2011 UPDATED SW N ATLC SECTION GULF OF MEXICO... WEAK RIDGE EXTENDS E TO W ALONG 29N PER EARLY PRELIMINARY SURFACE ANALYSIS. LATEST BUOY REPORTS THROUGHOUT INDICATE LIGHT WINDS AND LOW SEAS. HIGHER WIND AND SEA CONDITIONS PREVAIL OVER THE FAR SE WATERS WHERE A TIGHT PRES GRADIENT THERE IS MAINTAIN NE-E WINDS OF 15-20 KT THERE DUE TO THE RIDGE TO THE N AND WEAK LOW PRES IN THE NW CARIBBEAN SEA. THESE WINDS WERE CONFIRMED BY AN OBSERVATION FROM SHIP "LAW0O" AT 25N84W...AND BY THE WESTERN MOST FRINGE OF AN ASCAT PASS OVER THE MIDDLE STRAITS OF FLORIDA. BUOY REPORTS SHOW SEA HEIGHTS IN THE RANGES OF 1-3 FT...EXCEPT IN THE FAR SE GULF PORTION WHERE SEAS ARE IN THE RANGE OF 4-7 FT WITH THE NE-E 20 KT WINDS. WAVEWATCH GUIDANCE LOOKS REASONABLE FOR THE GULF...EXCEPT MAYBE 1-2 FT BELOW IN VALUES OVER THE FAR SE GULF AND STRAITS OF FLORIDA WHERE STRONGER E FETCH IS OCCURRING. WILL TAKE THIS INTO CONSIDERATION THROUGH FRI...OTHERWISE WILL FOLLOW REST OF VALUES FOR REMAINDER OF GULF FOR THIS FORECAST PERIOD. MODELS SUGGEST THAT THE RIDGE WILL CHANGE LITTLE THROUGH MON AS WEAK LOW PRES IN THE NW CARIBBEAN MOVES SLOWLY NW. THE LOW WILL WEAKEN INTO A TROUGH AS IT MOVES TO NEAR WESTERN CUBA AND THE FAR SE WATERS SAT...AND TO THE SOUTHERN MIDDLE GULF SUN. ALTHOUGH THIS SYSTEM WILL BE WEAK...THE PRES GRADIENT BETWEEN IT AND THE RIDGE WILL BE TIGHT ENOUGH TO ALLOW FOR THE NE-E 20 KT WINDS TO CONTINUE OVER THE FAR SE WATERS THROUGH AT LEAST EARLY FRI EVENING AT WHICH TIME THESE WINDS WEAKEN TO 10-15 KT AND SHIFT TO E-SE. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... THE BROAD AREA OF LOW PRES OVER THE NORTHWESTERN CARIBBEAN SEA DURING THE PAST SEVERAL DAYS HAS BECOME RATHER ILL-DEFINED SINCE THE LAST 24-48 HOURS UNDER UPPER LEVEL SW SHEAR INITIATED BY AN UPPER LEVEL CYCLONIC CIRCULATION LOCATED NEAR 26N88W. AS OF 0600 UTC THIS MORNING THE CENTER OF THE WEAK LOW WAS IDENTIFIED TO BE NEAR 19N31W...OR ABOUT 90 NM SW OF GRAND CAYMAN. A TROUGH EXTENDS FROM NORTHEASTWARD TO ACROSS CENTRAL CUBA. SATELLITE IMAGERY SHOWS AMPLE DEEP MOISTURE TO THE E OF THE LOW NOW CONFINED TO N OF 17N ALLOWING FOR CLUSTERS OF TSTMS TO AFFECT THE WATERS AROUND EASTERN CUBA AND HISPANIOLA. GUSTY WINDS CAN BE EXPECTED WITH THE TSTMS...BUT SHOULD MORE CONFINE TO THE OUTER REACHES OF THE OFFSHORE WATERS AND MOSTLY IN THE COASTAL WATERS OF EASTERN CUBA...HISPANIOLA AND PUERTO RICO THROUGH AT LEAST THE NEXT 36 HOURS. A PARTIAL ASCAT PASS FROM LATE LAST NIGHT REVEALED SE 15 KT WINDS BETWEEN JAMAICA AND THE LOW...AND NE WINDS OF 15-20 KT IN THE NORTHERN SEMICIRCLE OF THE LOW. SEAS THERE ARE IN THE RANGE OF 3-6 FT. AS THE LOW SLOWLY MOVES NW THROUGH SAT WHILE WEAKENING INTO A TROUGH...EXPECT WINDS OVER JUST ABOUT THE ENTIRE WESTERN CARIBBEAN W OF ABOUT 80W TO BECOME LIGHT IN A SLY DIRECTION. TRADES BEGIN TO INCREASE OVER THE CENTRAL AND EASTERN CARIBBEAN STARTING THU NIGHT AS CENTRAL ATLC RIDGING BUILDS SW TOWARDS THE NORTHERN TROPICAL N ATLC. THESE WINDS WILL REACH 20 KT THU NIGHT THROUGH FRI NIGHT...AND POSSIBLY 20-25 KT SAT AND OVER THE SOUTHERN SECTION OF THE EASTERN CARIBBEAN SEA WITH SEAS MAXING OUT TO 8 OR 9 FT. SW N ATLC...UPDATED NE TO E WINDS OF 15-20 KT ARE CONFINED TO S OF 27N W OF 76W...AND FROM 22N TO 26N E OF 76W DUE TO A TIGHT PRES GRADIENT BETWEEN HIGH PRES OVER THE NORTHERN AND CENTRAL WATERS...AND THE LOW PRES AND TROUGH IN THE NW CARIBBEAN SEA. MAXIMUM SEAS OBSERVED ARE ABOUT 6-7 FT W OF THE BAHAMAS...AND FROM 22N TO 26N E OF 76W. GLOBAL MODELS FORECAST THE AREA OF HIGH PRES TO SLIDE SE THROUGH SAT AS IT WEAKENS. IN THE MEANTIME WEAK LOW PRES JUST E OF THE FAR SE WATERS MOVES NE. GLOBAL MODELS AND EVEN THE REGIONAL NAM HAVE COME INTO PRETTY GOOD AGREEMENT THAT LOW PRES FORMS BETWEEN THE BAHAMAS AND CENTRAL CUBA THIS AFTERNOON OR EVENING AND TRACKS IT NWD TO OVER OR JUST E OF THE CENTRAL BAHAMAS THROUGH FRI NIGHT...BEFORE LIFTING N OF AREA LATE SAT NIGHT OR EARLY SUN MORNING. THE GFS IS THE EXCEPTION BY TAKING IT NE ACROSS THE SE BAHAMAS...AND KEEPING IT TO THE E OF THE BAHAMAS FOR FRI AND SAT. WILL BEGIN TO INTRODUCE THIS FEATURE AS WEAK 1009 MB LOW ON THE 36 HOUR WINDWARD CHART VALID 12 UTC JUN 10...AND AS WEAK LOW AS IT REACHES NEAR 29N76W WITH PRES OF 1011 MB IN 72 HOURS. THE MAIN ISSUE WITH THIS FEATURE WILL BE THE TIGHT GRADIENT THAT SETS UP TO ITS N AND NE BETWEEN IT AND WEAK HIGH PRES OVER THE NE PORTION OF THE AREA. MOST OF THE MODELS FORECAST UP TO 30 KT IN THE TIGHT GRADIENT WIND AREAS N AND NE OF THE LOW AS IT TRACKS NWD. THE GFS EVEN FORECAST MINIMAL GALE FORCE WINDS FRI NIGHT INTO SAT TO THE NE OF THE LOW. FOR THIS FORECAST PACKAGE I PLAN ON BEING CONSERVATIVE WITH THE WINDS ATTRIBUTED TO THE LOW...AND WILL GO WITH A RANGE OF 20-25 KT IN ITS NORTHERN SEMICIRCLE. WILL CLOSELY MONITOR FUTURE MODEL TRENDS AND EVOLUTION OF PRES FIELD AROUND THE LOW ONCE IT FORMS AND BEGINS TO MOVE NWD IN ORDER TO MAKE ANY CONSIDERATIONS WITH REGARDS TO ADJUSTMENTS TO WIND SPEEDS. FOR SEAS RELATED TO THE LOW WILL START WITH ABOUT 8 FT FRI...THEN BUILD THEM TO 9 OR 10 FT ON SAT PENDING OUTCOME OF HOW LOW EVOLVED WITH RESPECT TO INTENSITY AND TO SEE HOW ELY FETCH ALREADY IN PLACE OVER THE WESTERN ATLC IS FURTHER ENHANCED BY GRADIENT IMPOSED BY THE LOW. WARNINGS... ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE