000 AGXX40 KNHC 170707 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 300 AM EDT TUE JUL 17 2012 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 RIDGE HAS SHIFTED S TO ALONG 26N E OF 88W. A WEAKENING AND ELONGATED UPPER LOW MOVING W IS NOTED AT 23N89W. AN ASSOCIATED SURFACE TROUGH IS ALONG 26N87W 23N89W. SCATTERED SHOWERS AND TSTMS ARE OVER THE ERN HALF OF THE GULF WITH THE MAJORITY OF THE ACTIVITY CURRENTLY IN THE NE PORTION. THE RIDGE IS MAINTAINING LIGHT S-SW WINDS TO ITS S AND MOSTLY LIGHT AND VARIABLE WINDS TO ITS N. OVER THE REMAINDER OF THE GULF THE LATEST BUOY OBSERVATIONS ALONG WITH THOSE REPORTS FROM OIL RIG PLATFORMS GENERALLY SHOW E-SE WINDS OF 10-15 KT AS WAS ALSO CONFIRMED BY A PARTIAL ASCAT PASS FROM 0248 UTC LAST NIGHT. OBSERVED SEAS ARE MOSTLY AT 2 FT...WITH 1-2 FT IN THE FAR ERN PORTION OF THE GULF. MODELS CONTINUE TO BE IN PRETTY GOOD AGREEMENT WITH THE RIDGE REMAINING NEAR 26N THROUGH TONIGHT BEFORE IT MOVES SLIGHTLY N THROUGH SAT WHILE EXTENDING WWD TO CENTRAL TEXAS. THE SURFACE TROUGH WILL GRADUALLY BECOME DIFFUSE THROUGH TONIGHT. THE PRES DIFFERENCE BETWEEN THE RIDGE AND BROAD LOW PRES OVER SE MEXICO AND THE FAR SW GULF WILL ALLOW FOR SE WINDS ON THE SW GULF ZONE TO INCREASE TO TONIGHT THROUGH WED NIGHT....AND TO 15-20 KT THU INTO FRI BEFORE DIMINISHING TO 10-15 KT DURING FRI AND INTO SAT. THE NRN PORTION OF A CARIBBEAN TROPICAL WAVE CURRENTLY PASSING ACROSS ERN CUBA IS EXPECTED TO MOVE OFF NW CUBA AND INTO THE FAR SE GULF WED NIGHT INTO THU...MOVE INLAND THE NRN YUCATAN PENINSULA THU NIGHT INTO AND FRI...THEN MOVE ACROSS THE ERN BAY OF CAMPECHE FRI NIGHT AND SAT. A SLIGHT ENHANCEMENT TO ELY WINDS MAY OCCUR IN THE WAKE OF THE WAVE. THE MULTIGRID NOAA WAVEWATCH III GUIDANCE WILL BE USED FOR THE THE OFFSHORES FORECAST AS IN THE PREVIOUS IT HAS INITIALIZED CLOSE TO REPORTED SEA STATE VALUES...AND ITS FORECAST THROUGH FRI (DAY 5) LOOKS REASONABLE. SW N ATLC S OF 31N W OF 65W... THE PRELIMINARY 0600 UTC SURFACE ANALYSIS HAS A RIDGE AXIS EXTENDING FROM A 1019 MB HIGH AT 26N67W SW TO S FLORIDA. SATELLITE WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL LOW JUST RECENTLY HAVING MOVED INLAND NE FLORIDA. THE NRN PORTION OF A CARIBBEAN TROPICAL WAVE IS OVER THE CENTRAL BAHAMAS EXTENDING SWD TO ERN CUBA. PARTIAL HIGH RESOLUTION ASCAT DATA FROM 0250 UTC LAST NIGHT ALONG WITH WRN ATLC BUOY OBSERVATIONS REVEALED S-SW WINDS OF 5-10 KT N OF THE RIDGE...AND E-SE WINDS OF 10-15 KT S OF THE RIDGE. HIGHER E WINDS OF 15-20 KT EXIST BETWEEN THE SE BAHAMAS AND PUERTO RICO DUE TO THE SLIGHTER TIGHTER PRES GRADIENT THERE. DEEP ATMOSPHERIC MOISTURE PREVAILS OVER THE FAR WRN PORTION OF THE BASIN TO THE S OF THE UPPER LEVEL LOW...AND ENE OF THE UPPER LOW OVER THE SRN GULF OF MEXICO WHERE UPPER LEVEL DIVERGENCE CAN BE FOUND. RESULTANT SCATTERED SHOWERS AND TSTMS WITH POSSIBLE GUSTY WINDS ARE OVER MUCH OF THESE THE FAR WRN ATLC WATERS AS CURRENTLY SEEN ON NWD RADAR DISPLAYS AND ON SATELLITE IMAGERY...WITH THE MOST CONCENTRATED PORTION OF THIS ACTIVITY LOCATED FROM OVER MUCH OF THE BAHAMAS TO ERN CUBA. MODELS HAVE A VERY PERSISTENT TREND IN FORECASTING THE RIDGE GRADUALLY SHIFT N TO 27N BY WED...AND TO 28N THU THROUGH SAT. THE 1019 MB HIGH WILL REMAIN STATIONARY AND STRENGTHEN TO 1021 MB TONIGHT...THEN DISSIPATE BY WED EVENING AS THE RIDGE BECOMES REINFORCED BY STRONGER CENTRAL ATLC RIDGING THAT BUILDS WSW. S OF THE RIDGE...E-SE 10-15 KT WINDS WILL PREVAIL E OF THE BAHAMAS WITH THE 15-20 KT E WINDS BETWEEN THE BAHAMAS AND PUERTO RICO TROUGH FRI. THE NRN PORTION OF A CARIBBEAN WAVE IS MOVING W THROUGH THE SE BAHAMAS AND WINDWARD PASSAGE EARLY THIS MORNING. IT MARKS THE LEADING EDGE OF THE 15-20 KT E WINDS MERGING WITH CENTRAL ATLC NE-E 20 KT WINDS THAT SPREAD WWD WED NIGHT THROUGH SAT. THE TROPICAL WAVE WILL MOVE ACROSS THE REMAINDER OF THE FAR SRN WATERS THROUGH EARLY WED NIGHT BEFORE IT ENTERS THE FAR SE GULF WATERS LATER ON WED NIGHT. THE WAVE WILL BE DEPICTED AS SUCH ON THE NEXT ISSUANCE OF THE TAFB MANUAL GRAPHICS. A SLIGHTER ENHANCED PRES GRADIENT BEHIND THE WAVE SHOULD LEAD TO E WINDS OF 15 KT WINDS OVER THE FAR SW WATERS NEAR THE COAST OF CUBA AND STRAITS OF FLORIDA WED NIGHT THROUGH SAT. THE SHOWERS AND TSTMS OVER THE FAR WRN ATLC WATERS WILL LINGER INTO TONIGHT BEFORE SAHARAN DUST (SAL) BEGINS TO ADVECT WWD ACROSS MUCH OF THE SRN WATERS AND CONTINUE THROUGH THE NEXT FEW DAYS. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... A TROPICAL WAVE MOVING W AT 10-15 KT IS ANALYZED ALONG 76W/77W N OF 15N ON THE 0600 UTC PRELIMINARY SURFACE ANALYSIS. BROAD LOW PRES COVERS THE FAR SW CARIBBEAN AND ADJACENT AREAS OF CENTRAL AMERCIA AND S AMERICA. SCATTERED WEAKENING TSTMS ARE WITHIN 120 NM W OF THE WAVE N OF 19N. THIS WAVE HAS BECOME ILL-DEFINED AT THE SURFACE...AND THERE IS ONLY SOME SLIGHT INDICATION OF IT IN THE LOW CLOUD MOTION SEEN ON SATELLITE IMAGERY. A BROAD AREA OF NE-E 20-25 KT WINDS COVERS MUCH OF THE CENTRAL CARIBBEAN SEA AS DETECTED BY THE HIGH RESOLUTION ASCAT PASS VALID 0246 UTC LAST NIGHT. IN ADDITION...BUOY OBSERVATIONS FROM ACROSS THE CENTRAL AND ERN CARIBBEAN SEA REVEAL MOSTLY NE-E 15 20 KT WINDS WITH SEAS OF 5-7 FT. SEAS OF 6-8 FT ARE LOCATED WITHIN THE AREA OF 20-25 KT WINDS WITH THE 8 FT SEAS NEAR 12N78W. ELSEWHERE ACROSS THE CARIBBEAN AND IN THE TROPICAL ZONES LIGHTER NE-E WINDS OF 10-15 KT ARE NOTED IN THE BUOY OBSERVATIONS...AND IN THE ASCAT PASS FROM 0104 UTC LAST NIGHT FOR THE TROPICAL N ATLC. THE OBSERVED BUOY AND ASCAT DATA MATCH PRETTY WELL WITH BNDRY LAYER MODEL WIND FIELD FROM BOTH THE GFS AND ECMWF MODELS. SEAS IN THE TROPICAL N ATLC ZONE HAVE LOWERED FROM THE 8-9 FT SEEN YESTERDAY IN THE NRN ZONE OF THE TROPICAL N ATLC TO 5-6 FT. HOWEVER SEAS THERE BUILD BACK TO 8 FT WED THROUGH FRI WITH DURATION/FETCH OF E 15-20 KT WINDS. SEAS ELSEWHERE IN THE CARIBBEAN ARE IN THE RANGES OF 4-6 FT IN THE CENTRAL AND ERN SECTIONS...AND 2-4 FT IN THE WRN SECTION AS REPORTED BY BUOYS 42056 AT 19.7N85W AND 42057 AT 17N81.5W. THE TROPICAL WAVE WILL REACH CENTRAL CUBA EARLY TONIGHT AND WED WRN CUBA BY EARLY WED NIGHT BEFORE ENTERING THE FAR SE GULF OF MEXICO LATER ON WED NIGHT AND INTO THU. WITH THE WAVE PASSING ACROSS THE CARIBBEAN THE MODERATE TO FRESH TRADES THROUGHOUT MUCH OF THE CENTRAL CARIBBEAN WATERS WILL BE FURTHER REINFORCED INTO MOST OF THU AND INTO FRI AS THE ATLC HIGH PRES RIDGE N OF THE AREA STRENGTHENS...WHILE AT THE SAME TIME RELATIVELY LOWER PRES IS PRESENT OVER THE SW CARIBBEAN SEA. THE RESULTANT TIGHTER PRES GRADIENT WILL ALLOW FOR THESE WINDS TO EXPAND IN AREAL COVERAGE WITH THE POSSIBILITY OF NE-E WINDS REACHING TO 30 KT ALONG OR NEAR THE COAST OF COLOMBIA LATE TONIGHT INTO WED MORNING...AND AGAIN LATE WED NIGHT. THE NOAA MULTIGRID WAVEWATCH III MODEL GUIDANCE BRIEFLY BUILDS SEAS RATHER HIGH...UP TO 14 FT IN THE SW CARIBBEAN WED BEFORE LOWERING THEM TO 10-11 FT THU...AND TEMPORARILY BUILDS THEM TO 12 FT FRI BEFORE LOWERING THEM TO 10-11 FT SAT. THE ENSEMBLE GUIDANCE FROM THE NOAA WAVEWATCH III COMBINED WITH THE FNMOC ENSEMBLE HAS EVEN HIGHER SEAS OF 16 FT ON WED AND 15 FT ON THU. THE 14-16 FT VALUES ARE ABOUT 2-3 FT HIGHER THAN WHAT WAS ADVERTISED IN RECENT DAYS...SO WILL FORECAST 11 OR 12 FT WHICH SEEMS MORE SUITABLE GIVEN DURATION AND AREAL COVERAGE OF THE MODERATE TO FRESH TRADES. THIS IS ALSO IN AGREEMENT WITH THE MEAN ENSEMBLE OF THE NOAA WAVEWATCH III COMBINED WITH THE FNMOC ENSEMBLES. NOTE...GRIDDED MARINE OUTPUT IS AVAILABLE AT WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE GULF OF MEXICO... .NONE. CARIBBEAN SEA... .NONE. SW N ATLANTIC... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ FORECASTER AGUIRRE