000 AGXX40 KNHC 070737 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 337 AM EDT Sun May 7 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 1017 mb located over the Central Gulf near 27N90W dominates the region, with associated gentle to moderate anticyclonic flow across the forecast waters. Seas have lowered to 4 to 5 ft over the eastern portion of the Gulf as the pressure gradient relaxes and previous generated northwest swell decays. The high pressure is forecast to slowly shift eastward reaching the NE Gulf waters by late Tuesday night, and remain there through Thursday allowing for moderate to fresh southeast winds to develop over the western Gulf and continue through Thursday. Fair conditions are expected to prevail over the basin under the control of the high pressure. A thermal trough will begin to move offshore the Yucatan Peninsula and move across the SW Gulf at night and into the morning hours through the period accompanied by fresh to locally strong northeast to east winds. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... The cold front that entered the NW Caribbean during the past few days is presently a dissipating stationary frontal boundary that extends from eastern Cuba southwest to near 17N84W. This boundary will dissipate today. Northerly winds over the western Caribbean have diminished to mainly gentle winds per latest Ascat pass and reports from buoy 42056 located at 20N85W. The combination of a rather pronounced broad upper trough, that during the past few days was over the Gulf of Mexico, and ample deep layer moisture along and ahead of boundary is creating pockets of scattered showers and isolated thunderstorms between the boundary and a line from eastern Cuba to southern Nicaragua. This activity will gradually shift eastward through today, but is expected to begin to diminish this afternoon and tonight as the boundary dissipates and the upper trough flattens out as its translates eastward. Mainly gentle to moderate trades prevail over the central Caribbean, and moderate to fresh trades are noted per scatterometer data over the eastern Caribbean. Seas are generally under 6 ft across the basin. High pressure over the central Atlantic and low pressure near the coast of Colombia 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 dominate the majority of the Tropical N Atlantic zones, with the exception of a pocket of seas to 8 ft over the far southern portion of those zones. These seas are due to a previous pulse of northeast swell, however that pulse is losing its energy and so these seas will subside to below 8 ft late this morning or early in the afternoon. Thereafter, seas over the Tropical N Atlantic will be in the general range of 5 to 7 ft through Tuesday evening until the next set of northeast swell begins to arrive into the far eastern section of those zones late Tuesday night. This next set of northeast swell is estimated to be short-lived as it will already have peaked in energy as it propagates through those waters. The induced 6 to 8 ft seas are forecast to subside back to 5 to 7 ft on Wednesday. ...SW N ATLANTIC INCLUDING THE BAHAMAS... As of 06Z a cold front is analyzed along a position from 31N68W to 25N72W to 21N76W. The 0238Z Ascat pass suggests that the strong west to northwest winds that were present behind the front have diminished to gentle to moderate winds under a much weaker pressure gradient. Seas behind the front have lowered for the most part, except for an area of lingering seas of 8 to 10 ft in leftover northwest swell noted to the north of 28N west of the front to 76W. Similar seas are to the east of the front confined to the northern portion of zone AMZ115. Seas elsewhere over the basin, as observed in recent altimeter passes and in current buoy observations, are in the range of 4 to 7 ft east of the Bahamas, 3 to 5 ft north of the Bahamas west of 78W and 1 to 2 ft southwest of the Bahamas. Atmospheric instability attributed to the same upper trough described under the Caribbean Seas and Tropical N Atlantic section is still leading to numerous showers and thunderstorms within 240 nm east of the front, with the most concentration of this activity located to the north of 26N. This activity is capable of producing strong gusty winds as well as reduced visibilities. The cold front will reach a position from near 31N67W to 27N70W where it will become stationary to eastern Cuba by this evening. The remaining cold front portion will begin to weaken tonight as it moves eastward, and undergo the dissipation as it crosses 65W Monday evening. The stationary portion will begin to dissipate this evening. By Tuesday night, the remnants of the front are expected to have transitioned to a trough from near 25N65W to 21N67W and move little through Wednesday night. A cold front has moved to just offshore the South Carolina coast. This front will quickly move southeastward and brush the far northwest waters today. It will then rapidly weaken as it passes over the far north/central and northeast waters tonight through Monday night. Strong westerly winds are expected to the north of 30N and west of the front early today. High pressure will then become centered over the SW N Atlantic from early to the middle of next week. Over the southeastern zones, mainly moderate east to southeast winds with seas in the range of about 4 to 6 ft will prevail 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.