000 AGXX40 KNHC 211821 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 221 PM EDT THU MAY 21 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 AND ECMWF BLENDED WITH PREVIOUS OFFICIAL FORECAST. LATEST MWW3 USED FOR WAVE PARAMETERS (NWPS NOT AVAILABLE). HIGH CONFIDENCE. A WEAK 1017 MB HIGH PRES AREA LOCATED IN THE NE GULF DOMINATES THE REGION. THIS HIGH IS EXPECTED TO MEANDER OVER THE N-CENTRAL AND NE GULF THROUGH LATE TONIGHT AND MERGE WITH A RIDGE MOVING OFF THE MID-ATLC COAST ON FRI WHICH WILL ARRIVE BEHIND THE TAIL END OF A WEAK COLD FRONT. AS THIS NEW RIDGE BUILDS ACROSS THE AREA...GENTLE TO MODERATE NE-E WINDS WILL PREVAIL ACROSS THE EASTERN GULF WITH MAINLY MODERATE E-SE WINDS ACROSS THE WESTERN GULF. ALSO...FRESH TO LOCALLY STRONG WINDS WILL CONTINUE TO PULSE EACH EVENING THROUGH THE EARLY MORNING HOURS NEAR AND TO THE NW OF THE YUCATAN PENINSULA DUE TO LOCAL EFFECTS INDUCE BY A THERMAL TROUGH. THESE E-SE PULSES OF 20-25 KT WILL PROPAGATE WNW ACROSS THE SW GULF OF MEXICO EAST OF AN INVERTED TROUGH DURING THE MORNING HOURS...WITH THE TROUGH LOSING IDENTITY AND WINDS DIMINISHING TO 15-20 KT BY THE LATE MORNING/EARLY AFTERNOON HOURS EACH DAY. SEAS WILL BRIEFLY BUILD TO 5-7 FT ACROSS THE SW GULF IN ASSOCIATION WITH THESE WINDS. OTHERWISE...SEAS WILL BE GENERALLY UNDER 6 FT ACROSS THE WESTERN GULF AND UNDER 4 FT ACROSS THE EASTERN GULF. THE PRES GRADIENT BETWEEN A 1030 MB HIGH OVER THE U.S. MIDDLE ATLC STATES AND LOWER PRES OVER TEXAS AND NE MEXICO WILL BRING AN INCREASE IN WINDS AND SEAS ACROSS THE GULF WATERS BY SAT NIGHT. FRESH TO LOCALLY STRONG E-SE WINDS ARE EXPECTED ACROSS MOST OF THE GULF WITH BUILDING SEAS TO 8 FT ACROSS THE NW PART BY SUN. THESE MARINE CONDITIONS ARE FORECAST TO ALSO PERSIST ON MON... DIMINISHING SLIGHTLY BY TUE AS THE PRES GRADIENT SLACKENS A BIT. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: LATEST GFS AND ECMWF BLENDED WITH PREVIOUS OFFICIAL FORECAST. LATEST MWW3 USED FOR WAVE PARAMETERS (NWPS NOT AVAILABLE). HIGH CONFIDENCE. THE PRES GRADIENT BETWEEN RIDGING N OF AREA AND LOW PRES LOCATED OVER NW COLOMBIA WILL CONTINUE TO SUPPORT THE PULSING OF FRESH TO LOCALLY STRONG TRADE WINDS NEAR THE NW COAST OF COLOMBIA WITH RECENT ASCAT AND ASCAT-B SCATTEROMETER PASSES AND A RECENT CRYOSAT ALTIMETER PASS WHICH REGISTERED SEAS UP TO 8 FT VERIFYING THESE CONDITIONS. OTHERWISE...MODERATE TO FRESH TRADES WILL PREVAIL THROUGH SUN ACROSS THE REMAINDER OF THE AREA S OF 17N WHILE MODERATE TRADES ARE EXPECTED N OF 17N. WINDS AND SEAS WILL INCREASE E OF THE WINDWARD ISLANDS FRI AFTERNOON AND PERSIST THROUGH SUN NIGHT. IN ADDITION...EXPECT INCREASING WINDS AND SEAS ACROSS THE CENTRAL CARIBBEAN...IN THE GULF OF HONDURAS...AND NEAR THE WINDWARD PASSAGE DURING THE UPCOMING WEEKEND AS A STRONGER HIGH PRES MOVES ACROSS THE MIDDLE ATLC STATES INTO THE WESTERN ATLANTIC. MODEL GUIDANCE SUGGESTS TRADE WINDS OF 25-30 KT AND SEAS OF 10-12 FT NEAR THE COAST OF COLOMBIA BY EARLY SUN MORNING WITH SIMILAR WEATHER CONDITIONS PERSISTING MON THROUGH TUE. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: LATEST GFS AND ECMWF BLENDED WITH PREVIOUS OFFICIAL FORECAST. LATEST MWW3 USED FOR WAVE PARAMETERS (NWPS NOT AVAILABLE). HIGH CONFIDENCE. A 1019 MB HIGH PRES CENTER LOCATED NEAR 29N59W EXTENDS A RIDGE WESTWARD ACROSS THE SW N ATLC OFFSHORE WATERS ALONG 26N/27N TO NEAR JUPITER FLORIDA. RECENT SCATTEROMETER DATA SHOWED MAINLY LIGHT TO MODERATE BREEZE ANTICYCLONIC FLOW ACROSS MOST OF THE REGION WITH SEAS OF 2-4 FT E OF THE BAHAMAS BASED ON BUOY OBSERVATIONS AND ALTIMETER PASSES. AN EXCEPTION IS ACROSS THE WATERS NEAR HISPANIOLA AND W OF 70W WHERE THE MOST RECENT ASCAT PASS VERIFIED THE EXISTENCE OF MODERATE TO FRESH EASTERLY WINDS WHERE A LOCALIZED TIGHTER PRES GRADIENT IS PRESENT. THE HIGH PRES AND RIDGE WILL WEAKEN TONIGHT THROUGH FRI NIGHT AS WEAK TROUGHING DISRUPTS IT WHICH DEVELOPS FROM REMNANT FORCING LEFTOVER FROM AN OLD FRONT...AND AS A COLD FRONT CURRENTLY MOVING ACROSS CENTRAL GEORGIA APPROACHES THE NW PORTION HELPING TO KICK THE HIGH AND RIDGE OFF TO THE E. THE LATEST SCATTEROMETER DATA ALSO INDICATED THAT A WEAK PRE-FRONTAL TROUGH MAY ALREADY BE IN THE FAR NW CORNER WHERE A SW-W WIND SHIFT IS NOTED. THE ACTUAL COLD FRONT WILL ENTER THE NW PORTION LATE TONIGHT INTO FRI... MOVING SLOWLY ACROSS THE N WATERS REACHING A POSITION FROM 31N70W TO THE NW BAHAMAS BY FRI NIGHT WITH MAINLY MODERATE TO FRESH NE WINDS AND SEAS OF 4-5 FT BEHIND IT. THE FRONT WILL GRADUALLY DISSIPATE ACROSS THE N WATERS ON SUN WITH THE HIGH PRES BEHIND IT TAKING CONTROL OF THE WEATHER PATTERN OVER THE REGION. MODERATE TO FRESH NE-E WINDS WILL PREVAIL ACROSS THE FORECAST AREA SUN AND MON WITH BUILDING SEAS OF 4-6 FT E OF THE BAHAMAS. WINDS WILL FURTHER INCREASE TO 20-25 KT WITH SEAS OF 6-7 FT ACROSS THE SOUTH WATERS MAINLY S OF 22N W OF 70W...INCLUDING THE WINDWARD PASSAGE ON SUN NIGHT...AND THEN AGAIN ON MON NIGHT. THE REMNANTS OF THE FRONT WILL BECOME AN INVERTED TROUGH WHICH WILL RETROGRADE BACK TO THE W BEGINNING ON MON...REACHING 65W BY LATE TUE NIGHT INTO WED. THIS TROUGHING WILL TIGHTEN THE PRES GRADIENT ON EITHER SIDE OF ITS AXIS WITH NEARBY WINDS INCREASING TO FRESH TO STRONG LEVELS AS A RESULT WHICH WILL BUILD FRESH SEAS TO 7-9 FT. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... NONE. $$ *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 LEWITSKY. NATIONAL HURRICANE CENTER.