000 AGXX40 KNHC 201800 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 200 PM EDT THU AUG 20 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: GFS BLENDED WITH ECMWF FOR WINDS AND SEAS. HIGH CONFIDENCE. A RIDGE EXTENDING FROM NORTHERN FLORIDA TO SOUTH-CENTRAL TEXAS PREVAILS OVER NORTHERN WATERS. SCATTEROMETER DATA FROM LAST NIGHT SHOWED MODERATE EASTERLY WINDS N OF THE YUCATAN PENINSULA AND LIGHT TO GENTLE WINDS ELSEWHERE. MODEL GUIDANCE CONTINUES TO SHOWS A THERMAL TROUGH DEVELOPING EACH EVENING OVER THE YUCATAN PENINSULA THEN MOVING W INTO THE SW GULF AT NIGHT AND WEAKENING BY LATE MORNING. WEAK HIGH PRES IS EXPECTED TO REMAIN OVER THE NORTHERN GULF THROUGH TUE...WITH SEAS SLOWLY SUBSIDING TO BECOME 1-2 FT ACROSS THE ENTIRE BASIN BY MON AFTERNOON. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: GFS BLENDED WITH ECMWF FOR WINDS AND SEAS. MEDIUM CONFIDENCE. DANNY IN THE SOUTH-CENTRAL ATLC WAS UPGRADED TO A HURRICANE AT 1100 EDT THIS MORNING...AND IS EXPECTED TO REMAIN A HURRICANE AS IT MOVES CLOSER TO NORTHERN HALF OF THE TROPICAL N ATLC ZONES THIS WEEKEND. AS A SMALL TROPICAL CYCLONE IT WILL BE MORE PRONE TO PERIODS OF RAPID INTENSIFICATION AND/OR RAPID WEAKENING THAN LARGER TROPICAL CYCLONES. IT IS EXPECTED TO REMAIN A VERY SMALL CYCLONE WITH A TIGHT PRESSURE GRADIENT AND A SMALL AREA OF HIGH WINDS AND LARGE SEAS. HURRICANE DANNY IS EXPECTED TO CROSS 55W SAT NIGHT AND MOVE ACROSS THE LEEWARD ISLANDS LATE SUN NIGHT INTO MON MORNING. UNCERTAINTY IN THE FORECAST IS DIRECTLY RELATED TO THE TRACK AND INTENSITY OF HURRICANE DANNY. REFER TO THE LATEST FORECASTS ISSUED BY THE NATIONAL HURRICANE CENTER FOR THE MOST UP TO DATE DETAILS...INCLUDING THE FORECAST DISCUSSION AND THE OFFICIAL PROG REASONING. THE SUBTROPICAL RIDGE N OF THE AREA WILL WEAKEN THROUGH FRI AS A BROAD AREA OF LOW PRES SHIFTS SOUTHWARD TO SETTLE IN BETWEEN 60W AND 75W THIS WEEKEND. THE RIDGE WILL PUSH SOUTHWARD TO NEAR 22N BY SAT...AND WEAKEN THE NE-SW PRESSURE GRADIENT THAT NORMALLY EXISTS ACROSS THE CENTRAL CARIBBEAN IN AUGUST. AS A RESULT FRESH TO STRONG WINDS IN THE SOUTH-CENTRAL CARIBBEAN NEAR THE COAST OF NORTHERN COLOMBIA AND VENEZUELA WILL WEAKEN CONSIDERABLY THROUGH SAT...BECOMING 20 KT OR LESS BY LATE FRI NIGHT. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: GFS BLENDED WITH ECMWF FOR WINDS AND SEAS. LOW TO MEDIUM CONFIDENCE. SATELLITE IMAGERY SHOWS A BROAD AREA OF LOW PRESSURE CENTERED NEAR 31N68W DRIFTING SE INTO THE NORTHERN PORTION OF THE FORECAST AREA. THE LOW WILL MEANER THROUGH FRI NIGHT THEN SHIFT N OF THE AREA SAT. MEANWHILE...A TROUGH WILL EXTEND SW FROM THE DEPARTING TO THE CENTRAL BAHAMAS. HURRICANE DANNY IS EXPECTED TO PASS CLOSE TO THE VIRGIN ISLANDS AND PUERTO RICO EARLY NEXT WEEK AS A SMALL TROPICAL CYCLONE...THEN MOVE W-NW N OF HISPANIOLA AND CUBA TOWARD THE SOUTHERN BAHAMAS. ITS INTENSITY AT THAT POINT IS UNCERTAIN. GFS AND EUROPEAN MODEL GUIDANCE HAVE BEEN CONSISTENT WITH THE TRACK FORECAST OVER THE PAST SEVERAL MODEL RUNS...BUT THEIR INTENSITY OF THE CYCLONE HAS NOT. BOTH MODELS WEAKEN DANNY TO EITHER A LOW OR A STRONG TROUGH. THIS MAY BE RELATED TO SMALL SIZE OF THE SYSTEM. LARGE UNCERTAINTY IN THE FORECAST IS RELATED TO WHAT HAPPENS TO DANNY. REFER TO LATEST FORECAST ISSUED BY THE NATIONAL HURRICANE CENTER FOR DETAILS...INCLUDING THE FORECAST DISCUSSION AND THE OFFICIAL PROG REASONING. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... NONE. $$ *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 MUNDELL. NATIONAL HURRICANE CENTER.