000 AGXX40 KNHC 090453 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1253 AM EDT WED SEP 9 2015 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: LATEST GFS BLENDED INTO PREVIOUS OFFICIAL WHICH WAS A GFS/ECMWF BLEND. TAFB NWPS USED FOR SEAS HEIGHTS AND PRIMARY WAVE PERIOD WITH MANUAL ADJUSTMENTS TO MATCH OBSERVATIONS. MEDIUM-HIGH CONFIDENCE. A NARROW MID-UPPER LEVEL TROUGH CONTINUES NNE TO SSW ACROSS THE GULF FROM S-CENTRAL LA TO THE BAY OF CAMPECHE WITH AN EMBEDDED UPPER CYCLONE EVIDENT AT 27.5N92W. THIS UPPER SYSTEM IS NOW SHIFTING W...AND ALTHOUGH THE UPPER SUPPORT THAT HAS BEEN ENHANCING PEAK HEATING CONVECTION THE PAST FEW DAYS APPEARS REDUCED...THE SOUTHWESTERLY FLOW E OF THE TROUGH AXIS IS ADVECTING DEEP LAYERED MOISTURE NORTHWARD ACROSS THE GULF E OF TROUGH AXIS...AND ALSO ACROSS THE ENTIRE STATE OF FL. WILL ADJUST WEATHER GRIDS TO DENOTE POSSIBILITY OF TS EVERYWHERE E OF ABOUT 92W TODAY INTO THIS EVENING. AT THE LOW LEVELS A RIDGE EXTENDS FROM E TO W ALONG 27N WITH SOUTHERLY RETURN FLOW AT 10-15 KT ACROSS THE W-CENTRAL WATERS TO THE W OF 95W. AS A THERMAL TROUGH DEVELOPS OVER FL DURING PEAK HEATING TODAY EXPECT A SURFACE HIGH TO FORM ALONG THE RIDGE NEAR 26.5N83W AND LIKELY REDEVELOP AGAIN ON THU AFTERNOON...BUT BY THEN THE RIDGE WILL HAVE RETRACTED E ALLOWING A TROUGH TO DIP INTO THE N-CENTRAL WATERS AND MOVE E ON FRI. THE TROUGH IS EXPECTED TO ONLY BE ACCOMPANIED BY A SW-W-NW 5-10 KT WIND SHIFT. FORECAST THE TROUGH TO STALL FROM THE FL BIG BEND TO CENTRAL GULF ON SUN WITH STRONGER HIGH PRESSURE BUILDING OVER THE NW GULF SUPPORTING NE 10-15 KT WINDS LATE SUN INTO EARLY SUN NIGHT. FURTHER S...AN INVERTED THERMAL TROUGH WILL DEVELOP EACH AFTERNOON OVER THE YUCATAN PENINSULA...AND THEN MOVE W-NW ACROSS THE SW GULF WATERS...GENERALLY TO THE S OF 22N BETWEEN 90-93W DURING THE EVENING THROUGH LATE NIGHT HOURS...REACHING ALONG 94- 95W DURING THE EARLY DAYLIGHT HOURS...AND THEN DISSIPATING BY EARLY AFTERNOON. EXPECT THIS TROUGH TO BE ACCOMPANIED BY A NE-E- SE 15-20 KT NOCTURNAL EVENTS THROUGH SAT NIGHT...THEN GUIDANCE SUGGESTS A SLIGHTLY STRONGER EVENT TO OCCUR ON SUN NIGHT. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: LATEST GFS BLENDED INTO PREVIOUS OFFICIAL WHICH WAS A GFS/ECMWF BLEND. TAFB NWPS USED FOR SEAS HEIGHTS AND PRIMARY WAVE PERIOD WITH MANUAL ADJUSTMENTS TO MATCH OBSERVATIONS. MEDIUM-HIGH CONFIDENCE. THE ATLC RIDGE N OF THE AREA COMBINED WITH LOW PRESSURE OVER NW COLOMBIA WILL CONTINUE TO ENHANCE FRESH TRADES ACROSS THE THE S- CENTRAL WATERS...EXCEPT INCREASING TO STRONG WITHIN ABOUT 240 NM OF THE COLOMBIAN COAST TONIGHT INTO THU MORNING...BUILDING COMBINED SEAS TO 7-11 FT. THE GRADIENT IS EXPECTED TO RELAX ON THU SUPPORTING ONLY 15-20 KT NOCTURNAL EVENTS...WITH PERHAPS A SMALL AREA OF 20-25 KT FORMING WITHIN 30 NM OF THE EXTREME N COAST OF COLOMBIA ON THU NIGHT. GUIDANCE IS SUGGESTING AN INCREASE TO 20-25 KT AGAIN ON SUN NIGHT WITHIN 60 NM OF THE FAR N COAST OF COLOMBIA...AND ALSO ALONG THE FAR NW COAST OF VENEZUELA. A TROPICAL WAVE WILL PASS THROUGH THE GULF OF HONDURAS TODAY. A SECOND TROPICAL WAVE PASS THROUGH THE CENTRAL CARIBBEAN TODAY AND TONIGHT...AND THROUGH THE W CARIBBEAN ON THU AND FRI. A THIRD TROPICAL WAVE IS ENHANCING CONVECTION W OF THE WAVE AXIS ACROSS THE TROPICS WITHIN ABOUT 90 NM OF 11N58W. THIS WAVE WILL ENTER THE SE CARIBBEAN TONIGHT...REACH THE CENTRAL CARIBBEAN ON WED NIGHT THROUGH THU NIGHT...AND PASS THROUGH THE W CARIBBEAN THIS UPCOMING WEEKEND. CONDITIONS ASSOCIATED WITH THE WEAKENING REMNANT LOW OF TROPICAL STORM GRACE WILL ARRIVE NEAR 15N55W LATE WED NIGHT...REACH THE LEEWARDS EARLY FRI...AND REACH NEAR PUERTO RICO ON FRI NIGHT. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: LATEST GFS BLENDED INTO PREVIOUS OFFICIAL WHICH WAS A GFS/ECMWF BLEND. TAFB NWPS USED FOR SEAS HEIGHTS AND PRIMARY WAVE PERIOD WITH MANUAL ADJUSTMENTS TO MATCH OBSERVATIONS. MEDIUM-HIGH CONFIDENCE. THE GRADIENT OVER THE NE SEMICIRCLE OF A SURFACE LOW NEAR 31N62W HAS TIGHTENED INCREASING THE SURFACE WINDS TO 20-30 KT. THE SYSTEM HAS BEEN UPGRADED TO A TROPICAL DEPRESSION EIGHT. THE SYSTEM WILL MOVE N OF THE AREA TODAY AND IS EXPECTED TO STRENGTHEN TO A TROPICAL STORM. A BROAD FRONTAL TROUGH EXTENDS SE FROM THE CYCLONE TO BEYOND 28N55W ACCOMPANIED BY CONSIDERABLE CONVECTION. AS THE CYCLONE LIFTS N IT WILL DRAG A WEAK COLD FRONT SE ACROSS THE WATERS N OF 25N E OF 70W. A SURFACE HIGH IS AT 28N75W WITH A RIDGE EXTENDING SW TO FORT PIERCE FL...AND A RIDGE ALSO EXTENDS SE TO NEAR 24N65W. THE HIGH IS EXPECTED TO MEANDER THROUGH THU NIGHT...AND LOSE IDENTITY ON FRI WITH A MORE DOMINATE RIDGE EXTENDING FROM 30N55W TO 27N65W TO FORT PIERCE FL. THE RIDGE WILL SHIFT TO A PSN FROM 31N63W TO THE NW BAHAMAS ON SUN. SW FLOW N OF THE RIDGE WILL INCREASE TO 10-15 KT ON THU NIGHT WITH LITTLE CHANGE THROUGH SAT...THEN INCREASE TO 15-20 KT AHEAD A OF A WEAK COLD FRONT MOVING OFF THE NE FL COAST LATE SAT NIGHT. EXPECT E-SE 10-15 KT FLOW ACROSS THE TROPICAL WATERS S OF THE RIDGE EXCEPT INCREASING TO E AT 15-20 KT ALONG THE N COAST OF HISPANIOLA AND THE ATLC APPROACH TO THE WINDWARD PASSAGE DURING THE EVENINGS THE EASTERLY TRADES WILL INCREASE TO 15-20 KT ACROSS THE TROPICS WELL E OF THE LEEWARDS...NEAR 20N56W ON THU NIGHT IN ADVANCE OF REMNANTS OF TROPICAL STORM GRACE WHICH WILL REACH THE VIRGIN ISLAND AREA LATE FRI NIGHT..THESE 15-20 KT CONDITIONS WILL SPREAD N ACROSS THE TROPICS S OF 22N BETWEEN 65W AND 75W ON SAT AND SUN. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... NONE. $$ *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.HURRICANE WARNINGS.GOV/MARINE $$ .FORECASTER NELSON. NATIONAL HURRICANE CENTER.