000 AGXX40 KNHC 211759 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 159 PM EDT SUN JUL 21 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: GFS/ECMWF/OFFICIAL BLEND WITH GOOD CONFIDENCE. NWPS FOR WAVE HEIGHTS/PERIOD. THE UPPER CYCLONE NOW OVER THE AR-LA-MS CORNER APPEARS TO BE LIFTING NE. THE ASSOCIATED WEAK LOW LEVEL TROUGH IS DISSIPATING OVER THE NW COASTAL WATERS/PLAINS BUT STILL ACCOMPANIED BY TSTMS WITH FREQUENT LIGHTNING...00-06 HR WEATHER GRIDS ADJUSTED. THE ATLC RIDGE IS BUILDING W ALONG 27-28N AS EXPECTED...WITH THE AXIS REACHING THE TX COASTAL BEND JUST TO THE S OF REMNANTS OF THE LOW LEVEL TROUGH. THE RIDGE WILL GRADUALLY SHIFT S ALONG THE FL W COAST AND SHIFT N ALONG THE TX COAST WITH THE RIDGE EXTENDING FROM FL BAY TO THE NE TX COAST BY THU. SURFACE WINDS ALONG AND N OF THE RIDGE AXIS WILL BE 5-10 KT THROUGH THE PERIOD. THE E-SE RETURN FLOW S OF THE RIDGE IS ALREADY AT 15-20 KT WITH SEAS 2-4 FT. THE GRADIENT WILL FURTHER TIGHTEN OVER THE E BAY OF CAMPECHE THIS EVENING INTO MIDDAY MON SUPPORTING E-SE WINDS AT 20-25 KT AND SEAS 4-6 FT. THE GRADIENT WILL RELAX BY TUE SUPPORTING 10-15 KT S OF THE RIDGE WITH THE LOCAL INCREASE IN WINDS OFF THE NW COAST OF THE YUCATAN PENINSULA EACH EVENING. GUIDANCE IN GOOD AGREEMENT. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC... MODEL PREFERENCE: GFS/ECMWF/OFFICIAL BLEND WITH GOOD CONFIDENCE. NWPS FOR WAVE HEIGHTS/PERIOD OVER CARIBBEAN BASIN. QUASI-STATIONARY ATLC HIGH PRES WILL MAINTAIN FRESH TO STRONG TRADES ACROSS THE N-CENTRAL CARIBBEAN WATERS...AND NEAR GALE CONDITIONS ACROSS THE S-CENTRAL CARIBBEAN THE SMALL AREA OF MINIMAL GALE WINDS NEAR 12.5N76W ENDING ATTM. COMBINED SEAS ARE 8-12 FT FROM 11-17N BETWEEN 70-83W WITH EMBEDDED 12-15 FT SEAS FROM 12-14N BETWEEN 73-76W. THE GRADIENT WILL GRADUALLY RELAX OVER THE NEXT 2 DAYS WITH EASTERLIES AT 20-25 KT CONTINUING GENERALLY S OF 14N BETWEEN 73-82W WITH SEAS SUBSIDING TO 7-10 FT. THE GRADIENT WILL SUPPORT E-SE WINDS AT 20-25 KT ACROSS THE WESTERN GULF OF HONDURAS WITH SEAS TO 7 FT FOR ANOTHER DAY BEFORE DIMINISHING. A TROPICAL WAVE HAS REACHED ALONG 56W AND WILL ENTER THE E CARIBBEAN LATE TONIGHT AND CONTINUE W AS ATLC HIGH PRES TO THE N WEAKENS THE E TRADES WILL ACTUALLY DIMINISH TO 15-20 KT IN THE WAKE OF THIS WAVE. A RECENT ASCATB PASS ALONG THE W COAST OF AFRICA PROVIDES ENOUGH DATA TO INTRODUCE A TROPICAL WAVE ALONG 16W ON THE 12Z ANALYSIS. THE OPERATIONAL GFS HAS COMPLETELY REVERSED ON THE LATEST 12Z RUN...AND NO LONGER QUICKLY DEVELOPS A STRONG TROPICAL SYSTEM AND PROGRESSES IT W ACROSS THE TROPICAL ATLC REACHING ALONG 35W ON WED NIGHT. SIGNIFICANT CONVECTION YESTERDAY LIKELY RESULTED IN PREVIOUS GFS RUNS TO BE MUCH HIGHER THAN OTHER GUIDANCE. THE CMC IS THE ONLY GUIDANCE NOW SUGGESTING A CLOSED SURFACE LOW AS THE WAVE PASSES 35W ON WED NIGHT. THE LATEST GFS IS SUGGESTING A SMALL LOW ALONG THE WAVE ACROSS THE ATLC WATERS E OF 35W THEN OPENS THE SYSTEM BACK TO A WAVE ACCOMPANIED BY 20-25 KT WINDS AS THE SYSTEM CROSSES 35W. TODAYS GRID PACKAGE WILL CONTINUE THIS COORDINATED MEDIUM RANGE AGREEMENT ON AN OPEN WAVE WITH 20-25 KT. SINCE THE NWPS DOES NOT COMPUTE THAT FAR OUT IN TIME...WILL CONTINUE MANUAL EDITS TO WAVE WATCH TO BRING SEAS IN LINE WITH 20-25 KT ALTHOUGH TODAYS EDITS ARE MINOR COMPARED TO THE REQUIRED ADJUSTMENTS YESTERDAY. MARINERS ADVISED TO MONITOR FUTURE GRID PACKAGES FOR MORE ADJUSTMENTS. ...SW N ATLANTIC W OF 55W INCLUDING THE BAHAMAS... MODEL PREFERENCE: GFS/ECMWF/OFFICIAL BLEND WITH GOOD CONFIDENCE. A 1023 MB SURFACE HIGH PRES IS QUASI-STATIONARY NEAR 29N66W WITH A RIDGE EXTENDING W TO THE CENTRAL FL COAST. THE HIGH WILL DRIFT SLOWLY NE PASSING TO THE S OF BERMUDA ON MON...THEN SHIFT NE OF THE AREA WITH A RIDGE EXTENDING FROM BERMUDA TO CENTRAL SE FL BY MID WEEK. SLY FLOW N OF THE RIDGE IS AT 10-15 KT WITH BRIEF PERIODS OF 15-20 KT EXPECTED ALONG 31N THROUGH MON NIGHT...THEN THE GRADIENT WILL TIGHTEN AHEAD OF AN APPROACHING WEAK COLD FRONT OR TROUGH ON TUE SUPPORTING S-SW 15-20 KT EVERYWHERE TO THE N OF THE RIDGE THROUGH THU. THE GRADIENT WILL RELAX SOME BY THU NIGHT AS THE WEAK FRONT STALLS OVER LAND W OF THE AREA. E WINDS AT 10-15 KT/SEAS 3-5 FT ARE EXPECTED S OF 23N TO THE E OF THE BAHAMAS...EXCEPT E AT 20-25 KT/SEAS 4-6 FT NEAR ATLC APPROACH TO WINDWARD PASSAGE THROUGH THIS EVENING. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... GMZ011...NONE. GMZ013...NONE. GMZ015...NONE. GMZ017...NONE. GMZ019...NONE. GMZ021...NONE. GMZ023...NONE. GMZ025...NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... AMZ011...NONE. AMZ013...NONE. AMZ015...NONE. AMZ017...NONE. AMZ019...NONE. AMZ021...NONE. AMZ023...NONE. AMZ025...NONE. AMZ027...NONE. AMZ029...NONE. AMZ031...NONE. AMZ033...NONE. AMZ035...NONE. AMZ037...NONE. AMZ039...NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... AMZ111...NONE. AMZ113...NONE. AMZ115...NONE. AMZ117...NONE. AMZ119...NONE. AMZ121...NONE. AMZ123...NONE. AMZ125...NONE. AMZ127...NONE. *FOR DETAILED ZONE DESCRIPTIONS PLEASE VISIT: HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT: HTTP://WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP FOR ADDITIONAL INFORMATION PLEASE VISIT: HTTP://WWW.HURRICANES.GOV/MARINE $$ .FORECASTER NELSON. NATIONAL HURRICANE CENTER.