000 AGXX40 KNHC 150735 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 335 AM EDT THU AUG 15 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: PROVISIONAL NHC FORECAST USED FOR POSITION OF DEVELOPING LOW PRES. WW3 USED INITIALLY...AWAITING LATEST NWPS RUN BASED ON UPCOMING NHC FORECAST. LOW CONFIDENCE. A SURFACE RIDGE EXTENDS FROM CENTRAL FLORIDA TO THE CENTRAL TEXAS COAST. THE NORTHERN PORTION OF A TROPICAL WAVE IN THE NW CARIBBEAN IS MOVING E TO W ACROSS THE YUCATAN PASSAGE. THERE IS BETTER CONSENSUS IN THE GLOBAL MODELS OVER THE SHORT TERM SHOWING A LOW PRES AREA MOVING ACROSS THE YUCATAN PENINSULA TO THE BAY OF CAMPECHE BY TONIGHT. IRONICALLY THE GFS SEEMS TO BE THE LEAST AGGRESSIVE MODEL WITH THIS LOW...AFTER HAVING BEEN AT TIMES THE MOST AGGRESSIVE MODEL DEVELOPING THE LOW OVER THE PAST COUPLE OF DAYS. WHILE A SHARP UPPER LEVEL TROUGH EXTENDING FROM THE NE GULF TO THE NORTHERN COAST OF YUCATAN IS PROVIDING SOME UPPER SUPPORT TO THIS FEATURE...A RECENT ASCAT PASS INDICATED THERE WAS NO SURFACE LOW PRES OVER THE NW CARIBBEAN. THUS FORECAST CONFIDENCE REMAINS LOW CONCERNING THE DEVELOPMENT...TRACK...AND ULTIMATE IMPACTS OF A LOW PRES SYSTEM IN THE SOUTHERN GULF FRI THROUGH SUN. OFFICIAL WIND AND WAVE HEIGHT FORECASTS WILL FOLLOW THE UPCOMING NHC PROVISIONAL FORECAST FOR THE LOW PRES. AN UPDATE TO THE GRIDDED FORECAST WILL BE OUT SHORTLY. AS THERE ARE NO ADVISORIES ATTM WINDS WILL BE CAPPED AT 30 KT. REGARDLESS OF THE EXTENT OF DEVELOPMENT WITH THE LOW PRES IN THE GULF...THERE IS HIGHER CONFIDENCE OF INCREASED SOUTHERLY FLOW ACROSS THE CENTRAL GULF FRI AND SAT BETWEEN THE LOW/TROUGH AND THE ATLC RIDGE TO THE EAST. MOST GUIDANCE SHOWS THE RIDGING BUILDING ACROSS THE NORTHERN GULF IN THE WAKE OF THE LOW/TROUGH EARLY NEXT WEEK. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: PROVISIONAL NHC FORECAST USED FOR POSITION OF DEVELOPING LOW PRES IN NW CARIBBEAN. OTHERWISE PREVIOUS FORECAST BLENDED WITH LATEST GFS. WW3 USED INITIALLY...AWAITING NWPS RUN BASED ON UPCOMING NHC FORECAST. MODERATE CONFIDENCE. THE 06 UTC SURFACE ANALYSIS SHOWS A TROPICAL WAVE IN THE GULF OF HONDURAS NEARLY ONSHORE OVER BELIZE AND THE YUCATAN PENINSULA. A SURFACE LOW HAD BEEN ANALYZED EARLIER ALONG THE WAVE AS IT MOVED THROUGH THE NW CARIBBEAN. WHILE A BROAD MID LEVEL CIRCULATION IS CLEARLY DEFINED...THERE IS SOME DOUBT WHETHER A SURFACE LOW STILL EXISTS SINCE A 0330 UTC ASCAT PASS INDICATED ONLY AN OPEN WAVE. CONVECTION IS ALSO FALTERING AT THE MOMENT. ELSEWHERE THE MAIN ISSUE IN THE SHORT TERM IS THE PRESENCE OF 30 KT TRADES OFF COLOMBIA WITH 20 TO 25 KT WINDS OVER MUCH OF THE REMAINDER OF THE CENTRAL CARIBBEAN. THE STRONG TO NEAR GALE FORCE FLOW IS THE RESULT OF HIGH PRES BUILDING N OF THE AREA INTO THE CARIBBEAN IN THE WAKE OF THE TROPICAL WAVE NOW MIGRATING THROUGH THE NW CARIBBEAN. RECENT ALTIMETER DATA ALONG WITH BUOY AND SHIP OBSERVATIONS INDICATE WAVE HEIGHTS REACHING 8 TO 10 FT IN THE CENTRAL CARIBBEAN. MODERATE TRADES COVER THE EASTERN CARIBBEAN WITH SEAS OF 5 TO 7 FT OUTSIDE OF THE LEE OF THE ISLANDS. MODERATE TO FRESH E TO SE WINDS ARE NOTED OVER THE WESTERN CARIBBEAN...ALTHOUGH THIS WILL LIKELY INCREASE SLIGHTLY TODAY AND TONIGHT AS THE TROPICAL WAVE SHIFTS W. THE TRADE WINDS OVER THE S CENTRAL CARIBBEAN WILL DIMINISH THROUGH FRI AS A TROPICAL WAVE ENTERS THE EASTERN CARIBBEAN TONIGHT...REACHING THE CENTRAL CARIBBEAN BY LATE FRI AND THE WESTERN CARIBBEAN SAT BEFORE BECOMING DIFFUSE. WINDS TO 25 KT CANNOT BE RULED OUT OFF COLOMBIA THROUGH THE WEEKEND PARTICULARLY IN THE OVERNIGHT AND EARLY MORNING HOURS. LOOKING AHEAD...THE ATLC RIDGE WEAKENS FURTHER AS ANOTHER TROPICAL WAVE APPROACHES FROM THE EAST AND MID LATITUDE ERODE THE RIDGE FROM THE NORTH...ALLOWING TRADE WINDS TO DIMINISH FURTHER. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: PREVIOUS FORECAST BLENDED WITH LATEST GFS/ECMWF WITH HIGH CONFIDENCE. WW3 USED INITIALLY...AWAITING LATEST NWPS RUN FOR UPDATE WAVE HEIGHTS. THE ATLC RIDGE EXTENDS E TO W ALONG ROUGHLY 28N TO NE FLORIDA. SCATTEROMETER AND BUOY OBSERVATIONS INDICATE SW FLOW TO 15 KT OVER AMZ111 OFF NE FLORIDA BETWEEN THE RIDGE AXIS AND A WEAK FRONTAL BOUNDARY DRAPED ACROSS THE DEEP SOUTH STATES. IN ADDITION TRADE WINDS TO 20 KT ARE NOTED S OF 22N NEAR THE APPROACHES TO THE WINDWARD PASSAGE. SEAS OF 2 TO 4 FT ARE NOTED W OF 65W...WITH 4 TO 6 FT IN NE AND E SWELL ACROSS AMZ127 NE OF THE LEEWARD ISLANDS. THE RIDGE AXIS WILL LIFT N THROUGH TODAY...ALLOWING WINDS TO DIMINISH OFF NE FLORIDA. THE NORTHERN EXTENT OF A TROPICAL WAVE WILL MIGRATE ACROSS THE WATERS S OF 22N...MAINTAIN MODERATE TO FRESH WINDS S OF 25N INTO SAT. THIS WILL BE FOLLOWED BY A SECOND TROPICAL WAVE APPROACHING THE LEEWARD ISLANDS BY LATE SAT/EARLY SUN...AND SWEEPING S OF THE AREA THROUGH MON. LOOKING FURTHER AHEAD TO NEXT WEEK...TROPICAL DEPRESSION FIVE HAS FORMED IN THE EASTERN ATLC. THIS IS FORECAST TO FORM INTO A TROPICAL STORM LATER TODAY AND MOVE WESTWARD ACROSS THE ATLC THROUGH EARLY NEXT WEEK...BUT WEAKEN SOMEWHAT BEFORE IT REACHES THE WESTERN ATLC IF IT DOES AT ALL. FOR MORE INFORMATION ON THIS SYSTEM...PLEASE SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS...FOUND AT HTTP://WWW.HURRICANES.GOV. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... GMZ011...NONE. GMZ013...NONE. GMZ015...NONE. GMZ017...NONE. GMZ019...NONE. GMZ021...NONE. GMZ023...NONE. GMZ025...NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... AMZ011...NONE. AMZ013...NONE. AMZ015...NONE. AMZ017...NONE. AMZ019...NONE. AMZ021...NONE. AMZ023...NONE. AMZ025...NONE. AMZ027...NONE. AMZ029...NONE. AMZ031...NONE. AMZ033...NONE. AMZ035...NONE. AMZ037...NONE. AMZ039...NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... AMZ111...NONE. AMZ113...NONE. AMZ115...NONE. AMZ117...NONE. AMZ119...NONE. AMZ121...NONE. AMZ123...NONE. AMZ125...NONE. AMZ127...NONE. *FOR DETAILED ZONE DESCRIPTIONS PLEASE VISIT: HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT: HTTP://WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP FOR ADDITIONAL INFORMATION PLEASE VISIT: HTTP://WWW.HURRICANES.GOV/MARINE $$ .FORECASTER CHRISTENSEN. NATIONAL HURRICANE CENTER.