000 AGXX40 KNHC 210748 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 348 AM EDT Sun May 21 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 into the Mississippi Valley. The pressure gradient between the ridge and lower pressure to the west of the Gulf over Mexico is generally maintaining moderate SE winds over the Gulf. Gentle to moderate winds are observed near the Northern Gulf Coast and over the SW Gulf. Fresh winds are noted to the N of the Yucatan Peninsula. Latest buoy observations and recent altimeter data show seas in the range of 3-5 ft over the Gulf. As the ridge shifts southward tonight through Tuesday in response to a weak frontal boundary that is stalling along the Northern Gulf Coast, winds over the Gulf will generally remain gentle to moderate. A stronger cold front will enter the NW Gulf late Tuesday night. SW winds ahead of the front will still be light to moderate due to the weak ridging ahead of the front. The front will be supported by an upper-level trough shifting eastward toward the United States East Coast through Wednesday. This will allow the front to reach from the NE Gulf to NW Yucatan Peninsula Wednesday night, and from South Florida to the Bay of Campeche by Thursday evening as it weakens. High pressure building in behind the front looks rather weak, and so winds following in the wake of the front will be light to moderate Wednesday through Thursday, with the exception of moderate to fresh winds over the NE Gulf. Seas before and after frontal passage should remain in the 3-6 ft range. The highest seas are expected in the far northern portions of the central and eastern Gulf. A thermal trough forming over then moving W from the Yucatan Peninsula tonight and Sunday night will generate fresh to strong NE to E winds. These winds will decrease Monday through Wednesday as the thermal troughs that develop during this time frame are weaker. ...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 the NW coast of Colombia. Showers and thunderstorms associated with the trough are noted over the SW Caribbean south of 12N. This activity is likely to continue through mid week. The pressure gradient between Atlantic ridging and the trough is generating fresh to strong trade winds over the central Caribbean, resulting in 7 to 10 ft seas between Colombia and Jamaica. These winds will continue today, then diminish tonight and Monday as the ridge weakens in response to low pressure moving eastward from the Eastern United States. Maximum seas of 10 ft will subside to around 9 ft by this evening, and to 8 ft on Monday. Moderate to fresh trades will continue over the remainder of the Caribbean. NE to E swell will produce combined seas of nearly 8 ft over the southern sections of the Tropical N Atlantic zones beginning on Monday night. ...SW N ATLANTIC INCLUDING THE BAHAMAS... The main feature maintaining the wind regime over the basin is a 1023 mb high centered near Bermuda that ridges westward to the southeast U.S. A surface trough is evident in satellite-derived wind data and in IR satellite imagery along a position from just N of the Leeward Islands to NE of the forecast waters near 28N56W. A small area of showers and thunderstorms associated with the trough is observed from 24N to 27N between 53W and 59W. This convection in the vicinity of an upper-level supporting the trough. The high near Bermuda is 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 today, then diminish on Monday and Tuesday as the ridge weakens and shifts east- southeastward. Winds will increase and veer from the S over the NW waters beginning on Wednesday in advance of a cold front moving across the SE U.S. The front will push offshore from the SE U.S. late Wednesday or early on Thursday and reach zones AMZ 111 and 115 by Thursday evening. Latest model guidance suggests that fresh to strong SW winds will precede the front accompanied by 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 McElroy. National Hurricane Center.