000 AGXX40 KNHC 190800 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 400 AM EDT THU JUL 19 2012 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO... THE SURFACE FEATURES ARE NOTED AS A RIDGE ALONG 26N...AND A TROPICAL WAVE MOVING IS MOVING W AT 15 KT ACROSS THE YUCATAN PENINSULA ALONG 89W/90W. IN THE UPPER LEVELS...A LOW IS JUST NW OF THE YUCATAN PENINSULA NEAR 21N90W. ANOTHER UPPER LEVEL LOW IS OVER FAR NE MEXICO. SCATTERED TSTMS SEEN EARLIER OVER THE FAR NE AND N CENTRAL GULF WATERS HAVE SINCE DISSIPATED. OTHER SCATTERED TSTMS ARE MOVING S OVER MUCH OF SE LOUISIANA. THE RIDGE IS MAINTAINING LIGHT SE-S WINDS TO ITS S...EXCEPT E-SE WINDS TO THE 88W AS REVEALED BY THE LATEST AND CURRENT BUOY OBSERVATIONS AND REPORTS FROM OIL RIG PLATFORMS. THE ASCAT PASS FROM 0348 UTC LAST NIGHT CAPTURED THESE WINDS AS WELL AS HIGHER SE WINDS OF 15-20 KT IN THE ERN SW GULF AND BAY OF CAMPECHE. SEAS ARE MOSTLY AT 2 FT...WITH 1-2 FT IN THE FAR ERN PORTION OF THE GULF AND 3-5 FT IN THE SW GULF ZONES. MODELS ARE IN GOOD AGREEMENT THAT THE RIDGE WILL REMAIN IN PLACE THROUGH FRI...THEN LIFT N TO 27N SAT AND TO JUST N OF THE AREA SUN AND MON. THE PRES DIFFERENCE BETWEEN THE RIDGE AND BROAD LOW PRES OVER SE MEXICO AND THE FAR SW GULF WILL ALLOW FOR THE SE 15-20 KT WINDS IN THE SW GULF TO CONTINUE MAINLY IN THE ERN PORTION THROUGH LATE TONIGHT AND INTO EARLY FRI BEFORE DIMINISHING TO NE-E 10-15 KT SAT THROUGH MON. THE NRN PORTION OF THE TROPICAL WAVE WILL MOVE ACROSS THE REMAINDER OF THE YUCATAN PENINSULA THROUGH TONIGHT...AND THEN ACROSS THE ERN BAY OF CAMPECHE TONIGHT INTO FRI...AND THROUGH THE REMAINDER OF THE BAY OF CAMPECHE AND SW GULF LATER ON FRI THROUGH AND INTO SAT. THE WAVE WILL BE ACCOMPANIED BY A WIND SHIFT...AND MOST LIKELY AID IN THE DEVELOPMENT OF CONVECTION OVER THE YUCATAN PENINSULA AND ADJACENT WATERS THROUGH SAT. THE MULTIGRID NOAA WAVEWATCH III GUIDANCE WILL BE USED FOR THE THE OFFSHORES FORECAST THROUGH DAY 5 AS IT AGAIN HAS INITIALIZED CLOSE TO REPORTED SEA STATE VALUES. SW N ATLC S OF 31N W OF 65W... THE PRELIMINARY 0600 UTC SURFACE ANALYSIS HAS A RIDGE EXTENDING ROUGHLY FROM 28N65W SW TO S FLORIDA. SATELLITE WATER VAPOR IMAGERY SHOWS THE UPPER LEVEL LOW THAT IN PREVIOUS DAYS MOVED FROM THE NW ATLC TO ACROSS NE FLORIDA IS NOW OVER ERN GEORGIA AT 32N81W. PARTIAL HIGH RESOLUTION ASCAT DATA FROM JUST PAST 0200 UTC LAST NIGHT ALONG WITH WRN ATLC BUOY OBSERVATIONS REVEALED S-SW WINDS OF 10-15 KT N OF THE RIDGE W OF 73W...AND S-SW 5-10 KT WINDS E OF 73W. E-SE WINDS OF 10-15 KT ARE NOTED S OF THE RIDGE...WITH E WINDS OF 15-20 KT BETWEEN THE SE BAHAMAS AND PUERTO RICO DUE TO THE SLIGHTER TIGHTER PRES GRADIENT THERE. THE GLOBAL MODELS FORECAST THE RIDGE TO BEGINS TO STRENGTHEN AS IT SLOWLY LIFTS N TO 28N TONIGHT AND SAT...AND TO 30N SUN AND MON. 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 THROUGH THE PERIOD. AS THE RIDGE STRENGTHENS A TROPICAL WAVE WILL BE PASSING THROUGH THE CENTRAL AND WRN CARIBBEAN. THE PRES DIFFERENCE BETWEEN THE HIGH AND THE TROPICAL WAVE ALONG WITH RELATIVELY LOWER PRES S OF THE BASIN WILL RESULT IN AN EXPANSION OF THE 15-20 KT WINDS OVER THE FAR SRN WATERS THROUGH MON WITH THE WRN EDGE OF THE SWATH OF THESE WINDS EXPANDING AS FAR W AS THE STRAITS OF FLORIDA THROUGH THE PERIOD. GFS/ECMWF WITH UKMET FOLLOWING CLOSE BEHIND. WILL USE BNDRY WIND GUIDANCE FROM THESE MODELS FOR GUIDANCE IN THIS FORECAST PACKAGE. CARIBBEAN SEA AND TROPICAL N ATLC W OF 55W... ASCAT DATA FROM 0204 UTC LAST NIGHT ALONG WITH WIND OBSERVATIONS FROM BUOY 42058 AT 15N75W NOTED A BROAD SWATH OF NE-E 20-25 KT WINDS COVERING MUCH OF THE CENTRAL CARIBBEAN SEA...AND WRN SECTION OF THE ERN CARIBBEAN. THE ASCAT PASS SUGGESTED THAT STEADY NE 25 KT WINDS ARE IN THE FAR SRN PART OF THE SW CARIBBEAN WITH POSSIBLE GUSTS TO 30 KT NEAR THE COAST OF COLOMBIA. SEAS OF 8 TO 11 OR 12 FT ARE IN THE FAR SW CARIBBEAN SEA WITH SEAS OF 6-9 FT ELSEWHERE IN THE SW CARIBBEAN SEA ZONES. THE ASCAT PASS ALONG WITH BUOY OBSERVATIONS SHOWED MOSTLY NE-E 15-20 KT WINDS WITH SEAS OF 4-7 FT OVER THE ERN CARIBBEAN SEA AND TROPICAL N ATLC WATERS N OF 14N. BUOY 42058 AT 15N75W IS CURRENTLY REPORTING SEAS 4-5 FT WHERE LIGHTER E WINDS OF 10-15 KT ARE NOTED. THESE WINDS ARE PRESENT OVER THE WRN CARIBBEAN W OF ABOUT 79W. THE OBSERVED BUOY AND ASCAT DATA MATCH PRETTY WELL WITH BNDRY LAYER MODEL WIND FIELD FROM BOTH THE GFS AND ECMWF MODELS. SEAS OF 4-7 FT IN THE TROPICAL N ATLC ZONE BUILD TO 8 FT N OF 15N LATER THIS MORNING AND CONTINUE THROUGH MON. SEAS OF 3-5 FT ARE FORECAST TO REMAIN IN THE WRN CARIBBEAN ZONES THROUGH THE PERIOD WITH AN E SWELL OVER THE SRN PART OF THOSE ZONES PRODUCING A COMBINED SEA OF ABOUT 6-7 FT BETWEEN 80W-85W. THE NE WINDS 0F 25-30 KT IN THE FAR SW CARIBBEAN SEA ARE EXPECTED TO DIMINISH TO 20-25 KT FRI AND CONTINUE TO MON. A TROPICAL WAVE APPROACHING THE LESSER ANTILLES WILL ENTER THE FAR ERN CARIBBEAN LATER THIS MORNING...AND MOVE ACROSS THE REST OF THE ERN CARIBBEAN THROUGH FRI...THE CENTRAL CARIBBEAN FRI NIGHT AND SAT AND THE WRN PORTION OF THE CARIBBEAN SAT INTO MON AND W OF THE AREA LATER ON MON. THE PRES DIFFERENCE ARISING BETWEEN THE WAVE AS IT TRACKS WWD INTO THE CARIBBEAN AND THE CENTRAL ATLC RIDGE FORECAST TO BUILDING WWD AND STRENGTHEN...WILL PROLONG THE 15-20 KT E WINDS OVER MUCH OF THE ERN CARIBBEAN AND TROPICAL N ATLC THROUGH THE END OF THE FORECAST PERIOD. ONCE IT REACHES THE CENTRAL CARIBBEAN FRI NIGHT THE SAME SITUATION WITH REGARDS TO THE PROLONGING OF THE STRONGER NE-E TRADES WILL OCCUR ALONG WITH AN EXPANSION OF THE AREAL COVERAGE OF THESE SAME WINDS. THE NOAA MULTIGRID WAVEWATCH III MODEL GUIDANCE BRIEFLY BUILDS SEAS RATHER HIGH...UP TO 15 FT IN THE SW CARIBBEAN TODAY BEFORE LOWERING THEM TO 10-12 FT THU...AND TO 10-11 FRI AND 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. THIS IS ABOUT 2-3 FT HIGHER THAN WHAT WAS ADVERTISED IN RECENT DAYS...SO I PLAN ON KEEPING THE CURRENTLY ADVERTISED MAX OF 12 FT THROUGH AT LEAST FRI FOR THE SW CARIBBEAN WATERS WHICH SEEMS MORE SUITABLE GIVEN DURATION AND AREAL COVERAGE OF THE MODERATE TO FRESH TRADES. THIS IS ALSO RATHER CLOSE TO THE MAX OF 13 FT INDICATED BY 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