000 AGXX40 KNHC 090801 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 401 AM EDT Tue May 9 2017 Marine Weather Discussion for the Gulf of Mexico, Caribbean Sea, and Tropical North Atlantic from 07N to 19N between 55W and 64W and the Southwest North Atlantic including the Bahamas ...GULF OF MEXICO... High pressure of 1019 mb located over the NE Gulf near 28N87W dominates the region, producing a gentle to moderate anticyclonic flow across the forecast waters. Latest buoy and altimeter data show relatively low seas throughout, with seas in the range of 1 to 3 ft over the eastern and central Gulf waters and 3 to 5 ft seas over the western Gulf waters, with the exception of higher seas in the range of 5 to 6 ft over the far western portion near the central and southern Texas coast. The high pressure center is forecast to remain over the NE Gulf through Thursday night, with the associated gradient continuing to support moderate to fresh southeast winds over the western Gulf. The high pressure will then shift to east of the Gulf on Friday in response to a weak cold front that models depict will reach the far western Gulf at that time. The front is then forecast to reach a position from the NE Gulf to inland far southern Texas on Saturday. Weak high pressure will build in behind the front, with light to moderate northerly winds expected over the western half of the Gulf by late on Saturday, and light to moderate south to southwest elsewhere. Seas will be rather low at that time, with wave guidance suggesting 2 to 3 ft. A thermal trough will move offshore the Yucatan Peninsula and across the SW Gulf at night and into the morning hours through Friday. A surge of fresh to locally strong easterly winds and seas in the 6 to 7 ft range will accompany this trough. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... Cloudiness along with shower/thunderstorm activity continue to diminish across the central Caribbean as dry aloft continues to infiltrate the western and central portions of the Caribbean in the wake of the upper level trough that has now shifted a bit further to the east. A surface trough spun off from the upper trough is analyzed from the just west of Puerto Rico to 14N67W. Scattered showers and isolated thunderstorms are noted within 60 nm east of the trough north of 16N. This feature and associated shower and thunderstorm will continue to translate eastward through Friday. The eastern segment of eastern Pacific monsoon trough reaches to just south of Costa Rica and Panama. Weak low pressure is along this portion of the trough, and given the presence of deep atmospheric moisture there, scattered showers and thunderstorms are increasing in coverage south of 13N and west of the Colombia. This pattern of active weather across that portion of the Caribbean is likely to continue through the next few days. Mainly moderate to locally fresh trades prevail over the central and eastern Caribbean per scatterometer data and ship and buoy observations. Seas are generally under 6 ft across the entire basin. High pressure over the central Atlantic and low pressure near the coast of Colombia associated with the monsoon trough will support moderate to locally fresh trade winds over the central and eastern Caribbean, and Tropical N Atlantic forecast waters through the forecast period. Seas of 6 to 7 ft in northeast swell dominate the majority of the Tropical N Atlantic zones, however, wave model guidance suggests that the next set of long-period northeast swell will arrive into the eastern sections of the Tropical N Atlantic on Thursday and persist through Friday night with resultant combined wave heights maxing out to around 8 to 9 ft. ...SW N ATLANTIC INCLUDING THE BAHAMAS... A weakening frontal boundary extends from from 31N65W to just northeast of the southeast Bahamas. The widespread bands of numerous showers with embedded isolated thunderstorms observed the past few days along and east of this boundary have moved to the east of 65W. Only narrow lines of scattered showers and isolated thunderstorms remain confined to the eastern sections of zones AMZ115 and AMZ113. This activity will also move east of the basin north of 25N, but linger south of 25N where a surface trough is along 67W. A weak surface trough is analyzed from near 31N76W to 28N80W. This feature will move eastward through tonight while dissipating, with no significant impacts on winds and seas. Mainly gentle to moderate northwest winds and seas in the range of 3 to 5 ft are present between the frontal boundary and trough. Lower seas of 1 to 3 ft are northwest of the trough, while seas of 1-2 ft are west and southwest of the Bahamas. Seas elsewhere are in the 4 to 5 ft range. East of the front, south to southwest winds of 10 to 15 kt are noted north of 25N, and east to southeast 10 to 15 kt winds are south of 25N east of the front and surface trough along 67W. The trough along 67W will continue to shift eastward reaching the vicinity of Puerto Rico early on Wednesday, then the vicinity of the U.S. and British Virgin Islands by Thursday night where surface moisture progs it to slow down and gradually lose its identity through Friday. Weak high pressure behind the trough over the northwest waters will eventually develop into a ridge axis roughly along 26N/27N on Thursday as it is forced south-southeastward through Friday in response to a couple of fronts that brush the far northern waters. These fronts will be preceded by moderate to fresh southwest to west winds, with fresh to strong winds now indicated by latest model runs to occur over much of zone AMZ115 on Friday. Seas with these are expected to be in the 5 to 8 ft range, with the highest of these over the northern and northeast portions of zone AMZ115 on Friday and Friday night. This will be reflected in the latest NDFD wave height grids. Seas elsewhere will change little through the forecast period. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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.nhc.noaa.gov/marine $$ .Forecaster Aguirre. National Hurricane Center.