000 AGXX40 KNHC 051742 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 142 PM EDT MON AUG 5 2013 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...AND THE SW N ATLANTIC INCLUDING THE BAHAMAS. ...GULF OF MEXICO... MODEL PREFERENCE: HIGH CONFIDENCE. LATEST GFS/ECMWF BLENDED WITH OFFICIAL FORECAST. NWPS USED FOR WAVE PARAMETERS. 1019 MB HIGH PRES CENTERED OVER THE SE GULF NEAR 24N86W IS MAINTAINING LIGHT TO MODERATE WINDS AND SEAS GENERALLY 2 FT OR LESS OVER MUCH OF THE GULF. A WEAK FRONTAL BOUNDARY IS SAGGING S THROUGH THE DEEP SOUTH STATES...AND WILL STALL ACROSS NORTHERN FLORIDA TONIGHT AND TUE BEFORE BECOMING DIFFUSE THROUGH MID WEEK. OPERATIONAL MODELS ARE IN BETTER AGREEMENT INDICATING THE HIGH PRES SHIFTING N AHEAD OF A PRE- FRONTAL TROUGH AHEAD OF THE FRONTAL BOUNDARY OFF THE EAST COAST OF FLORIDA THAT WILL DRIFT WEST ACROSS THE FLORIDA PENINSULA AND INTO THE EASTERN GULF WATERS WED AND THU. THE IMPACT OF THIS WILL BE MINIMAL...AMOUNTING TO BASICALLY A SHIFT IN THE WINDS TO SE OVER THE EASTERN GULF WITH WIND SPEEDS ONLY INCREASING AS HIGH AS 10 TO 15 KT LATE IN THE WEEK. THERE MAY BE A SLIGHT INCREASE IN SHOWERS AND TSTMS AS WELL OVER THE EASTERN GULF LATE IN THE WEEK...ALTHOUGH IS SPECULATIVE GIVEN THAT THE APPROACHING SURFACE TROUGH IS ON THE WEST SIDE OF AN UPPER LOW NOW CENTERED JUST E OF THE SOUTHERN BAHAMAS/TCI. THE SURFACE TROUGH IS EXPECTED TO PROGRESS INTO THE CENTRAL GULF FRI AND THE WESTERN GULF THIS WEEKEND...AS HIGH PRES BUILDS OVER THE EASTERN GULF. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC... MODEL PREFERENCE: HIGH CONFIDENCE THROUGH THU THEN MODERATE CONFIDENCE FRI AND SAT. LATEST GFS/ECMWF BLENDED WITH OFFICIAL FORECAST...EXCEPT GFS ONLY OVER S CENTRAL CARIBBEAN. NWPS USED FOR WAVE PARAMETERS. JUDGING BY OBSERVED TRENDS AT BUOY 42058 NEAR 15N75W BETWEEN COLOMBIA AND JAMAICA...THE ENHANCED WINDS AND SEAS OVER THE S CENTRAL CARIBBEAN ARE STARTING TO DIMINISH. SUSTAINED WINDS AT THE BUOY ARE 15 TO 20 KT WITH SEAS MAINLY 7 TO 8 FT. THIS IS MUCH LOWER THAN THE PAST SEVERAL DAYS WHEN STRONG HIGH PRES N OF THE AREA KEPT NEAR GALE FORCE WINDS IN PLACE OFF COLOMBIA. WINDS OFF COLOMBIA S OF THE BUOY ARE LIKELY STILL 20 TO 25 KT...WITH GENERALLY MODERATE TRADES ELSEWHERE ACROSS THE CARIBBEAN AND TROPICAL N ATLC WATERS W OF 55W. OVERALL THE WINDS AND SEAS WILL CONTINUE TO DIMINISH THROUGH TUE AHEAD OF A TROPICAL WAVE CURRENTLY BETWEEN 50W AND 55W THAT WILL PUSH INTO THE EASTERN CARIBBEAN TUE...CENTRAL CARIBBEAN WED...BEFORE WEAKENING AND SLOWING DOWN AS IT MOVES INTO THE WESTERN CARIBBEAN THU AND FRI. GLOBAL MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THIS SCENARIO. THE PASSAGE OF THE WAVE WILL WEAKEN THE PRES GRADIENT THAT HAS BEEN DOMINATING THE CARIBBEAN THE PAST SEVERAL DAYS. THERE MAY BE A SLIGHT INCREASE IN SHOWERS AND TSTMS WITH THE WAVE...AT LEAST ACROSS THE LEEWARD ISLANDS AND THE NE CARIBBEAN...BUT THE AIRMASS BEHIND THE WAVE APPEARS FAIRLY DRY AND NO APPRECIABLE INCREASE IN CONVECTION IS EXPECT AT LEAST FOR THE EASTERN AND CENTRAL CARIBBEAN. THE FORECAST BECOMES A LITTLE LESS CLEAR LATE IN THE WEEK TOWARD NEXT WEEKEND AS THE TROPICAL WAVE WILL LIKELY BECOME HARDER TO TRACK OVER THE WESTERN CARIBBEAN LATER IN THE WEEK. THE GFS AND ECMWF DO NOT CURRENTLY SHOW A DRAMATIC REBOUND IN TRADE WIND FLOW OVER THE S CENTRAL CARIBBEAN FRI INTO SAT AS THE RIDGE BUILDS N OF THE AREA BEHIND THE TROPICAL WAVE...AND THIS MAY BE A LITTLE UNDERDONE. THE GFS AT LEAST IS SHOWING AN INCREASE IN TRADE WIND FLOW OVER THE NORTHERN CARIBBEAN S OF HISPANIOLA. ...SW N ATLANTIC W OF 55W INCLUDING THE BAHAMAS... MODEL PREFERENCE: HIGH CONFIDENCE. LATEST GFS/ECMWF BLENDED WITH OFFICIAL FORECAST. WW3 USED FOR WAVE PARAMETERS. A WEAK COLD FRONT IS SAGGING SOUTHWARD INTO THE WATERS BETWEEN BERMUDA AND NE FLORIDA. THE FRONT WILL STALL THROUGH TUE AND BECOME DIFFUSE THROUGH MID WEEK. THE SUBTROPICAL RIDGE EXTENDS FROM 1030 MB HIGH PRES CENTERED NEAR 35W36W TO 27N65W THROUGH THE CENTRAL BAHAMAS. LIGHT TO MODERATE S TO SW FLOW N OF THE RIDGE IS ADVECTING MOIST UNSTABLE AIR ACROSS THE FRONTAL BOUNDARY. ALONG WITH INSTABILITY ALOFT ASSOCIATED WITH A COLD CORE UPPER LOW CENTERED NEAR 22N70W AND A DEEP LAYER DIGGING OFF THE EAST COAST...THIS IS SUPPORTING A BROAD AREA OF SHOWERS AND THUNDERSTORMS N OF 28N. A PRE- FRONTAL TROUGH EXTENDING FROM 30N74W TO THE FLORIDA KEYS WILL SHIFT WEST ACROSS THE FLORIDA PENINSULA ON WED. ANOTHER TROUGH LOCATED BETWEEN 50W AND 55W...ON THE NORTH END OF A TROPICAL WAVE...IS MOVING NNW S OF THE RIDGE AXIS. THIS TROUGH WILL WEAKEN AS IT DRIFTS TO THE NW BETWEEN THE BAHAMAS AND BERMUDA THU AND FRI. THIS WILL ERODE THE WESTERN EDGE OF THE RIDGE...AND KEEP ONLY MODERATE WINDS AND SEAS IN PLACE INTO THU. BY FRI INTO SAT...THE RIDGE WILL BUILD W BEHIND THE DEAMPLIFYING TROUGH AND ALLOW TRADE WIND FLOW TO INCREASE TO AT LEAST 20 KT S OF 22N WITH SEAS GRADUALLY BUILDING TO 7 FT ACCORDINGLY. LIGHT TO MODERATE WINDS WILL PERSIST N OF 22N WHERE THE RIDGE AXIS ITSELF EXTENDS ALONG ROUGHLY 28N. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... GMZ011...NONE. GMZ013...NONE. GMZ015...NONE. GMZ017...NONE. GMZ019...NONE. GMZ021...NONE. GMZ023...NONE. GMZ025...NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... AMZ011...NONE. AMZ013...NONE. AMZ015...NONE. AMZ017...NONE. AMZ019...NONE. AMZ021...NONE. AMZ023...NONE. AMZ025...NONE. AMZ027...NONE. AMZ029...NONE. AMZ031...NONE. AMZ033...NONE. AMZ035...NONE. AMZ037...NONE. AMZ039...NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... AMZ111...NONE. AMZ113...NONE. AMZ115...NONE. AMZ117...NONE. AMZ119...NONE. AMZ121...NONE. AMZ123...NONE. AMZ125...NONE. AMZ127...NONE. *FOR DETAILED ZONE DESCRIPTIONS PLEASE VISIT: HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT: HTTP://WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP FOR ADDITIONAL INFORMATION PLEASE VISIT: HTTP://WWW.HURRICANES.GOV/MARINE $$ .FORECASTER CHRISTENSEN. NATIONAL HURRICANE CENTER.