000 AGXX40 KNHC 201843 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 243 PM EDT Sat May 20 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 ridging extends from the SW Atlantic to the north/central Gulf this afternoon. The pressure gradient between the ridge and lower pressure over the south/central and SW portions of the Gulf is allowing for moderate to fresh east to southeast winds to continue across the mainly the central and eastern Gulf waters, while gentle to moderate winds are over the western part of the Gulf. Latest buoy observations and recent altimeter data show seas in the range of 3-5 ft over much of the central and eastern Gulf, except for lower seas of 2-3 ft noted to the northeast of a line from near 30N87W to 25N81W and north of 24N between 87W and 91W, and seas of 5-6 ft from 24N to 26N west of 95W. Little overall changes to winds and seas are expected through Sunday, then the aforementioned ridge will begin to shift southward Sunday night through Tuesday in response to a weak cold front that will emerge off the Texas coast. The gradient supporting the moderate fresh east to southeast winds will break down allowing for these winds to diminish to mainly gentle winds. The front will have little in the way of upper support as the upper flow pattern will be generally southwesterly. The front will become stationary and gradually lose its identity over the northern section of the Gulf through Tuesday. Then with more amplified upper troughing setting up over the central U.S. Tuesday, this will support a stronger cold front to move over the northern Gulf beginning on Tuesday night. With the upper trough shifting eastward through Wednesday, this will give impetus for the front to reach from the NE Gulf to NW Yucatan Peninsula Wednesday night, and from SW Florida to the northern Yucatan Peninsula by Thursday evening as it weakens. High pressure following in behind the front is expected to be rather weak, and so the gradient in the wake of the front should support mainly moderate northerly winds Wednesday through Thursday, with the exception of moderate to fresh winds over the northern portion of the NE Gulf. Southwest winds ahead of the front are expected to be in the moderate to fresh range. Seas ahead and behind of the front are forecast to be 3-6 ft, with the highest of the seas over the far northern portions of the central and eastern Gulf. A thermal trough will move off the Yucatan Peninsula tonight and Sunday night attendant by fresh to strong easterly winds. These winds will decrease by early in the afternoons as the trough moves west across the eastern half of the Bay of Campeche. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... The eastern portion of the E Pacific monsoon trough extends to along the NW coast of Colombia. Scattered showers and thunderstorms are noted south of 11N between 76W and 82W, while scattered showers and isolated thunderstorms are elsewhere south of 16N west of 80W. This activity is likely to continue into early next week. The pressure gradient between Atlantic ridging and the trough is supporting fresh to strong trade winds over the central Caribbean, resulting in 8 to 12 ft seas between Colombia and Jamaica. These winds will continue through Sunday, then diminish Sunday night and Monday as the ridge weakens in response to low pressure and an associated cold front moving eastward over the Eastern United States. The max seas of 12 ft will subside to around 9 ft by Sunday evening, and to 8 ft by early on Monday. Trade winds will remain as moderate to fresh over the remainder of the Caribbean. NE to E swell producing combined seas of up to 8 ft are forecast by Wave model guidance to propagate into the southern sections of the Tropical N Atlantic zones beginning on Monday night. ...SW N ATLANTIC INCLUDING THE BAHAMAS... The main feature controlling the wind regime throughout the basin is a 1022 mb high analyzed near Bermuda, with a ridge extending westward to the southeast U.S. A surface trough is evident both on the latest surface analysis and on satellite imagery along a position from just north of the Leeward Islands to northeast of the forecast waters near 23N60W. Another surface trough is east of the area from 25.5N62W to 30N58W. Scattered showers and isolated thunderstorms are observed south of about 24N and east of 64W. Isolated showers and thunderstorms are within 30 nm of a line from 26N65W to 27N68W. The troughs will weaken through late on Monday, while the ridge will change little, with the associated gradient maintaining gentle to moderate east to southeast winds north of 22N and moderate to fresh easterly winds south of 22N. The strongest winds will continue near the approaches to the Windward Passage through Sunday, then diminish early next week as the aforementioned ridge weakens and shifts east-southeastward. Upcoming changes will be seen in the form of increasing southerly flow over the northwest waters beginning on Wednesday in advance of a cold front that will move across the southeast U.S. at that time. The front is expected to push offshore the southeast U.S. late Wednesday or early on Thursday to across much of zones AMZ 111 and 115 by Thursday evening. Latest model guidance suggests that fresh to strong southwest winds are expected to precede the front along with seas of 6-8 ft. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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.