000 AGXX40 KNHC 171847 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 247 PM EDT Fri Mar 17 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 southeast U.S. southwestward to the Northwest gulf waters early this afternoon. The wind flow pattern over the basin is been steered by this ridge, with buoy observations noting gentle to moderate east to Southeast winds east of 92W, and moderate to locally fresh southeast to south winds west of 92W. Moderate to fresh east to southeast winds are confined to the eastern Bay of Campeche in the wake of the weakening thermal trough that moved offshore the Yucatan Peninsula last night. The buoy observations along with recent altimeter data are reporting seas in the 4-5 ft range throughout, with the exceptions of the far northwest portion where seas are higher in the 6-8 ft range from 25N to 28N west of 94W and in the far northeast gulf portion where seas are the lowest in the 1-2 ft range. The entire gulf is clear of any significant weather as very dry conditions aloft persist. Only minor upcoming changes are expected for this forecast period. The high pressure over the area will shift westward across the northern gulf on Saturday in response to deep upper troughing aloft that will send a cold southeastward over the northeast and the eastern part of the north-central waters.This front will have little impacts to winds and seas. The moderate to locally fresh southeast to south winds west of 92W diminish to generally the gentle to moderate range on Saturday. Model guidance indicates that at most, the front will be followed by moderate northwest winds Saturday night and Sunday, with relatively low seas. A thermal trough will continue to develop each afternoon over the Yucatan Peninsula, then move westward across the Bay of Campeche and waters south of 22N in the overnight time periods before becoming diffuse in the late morning hours near 94W. Strong northeast winds will precede the trough each evening and night, while fresh to strong east to southeast winds will follow the trough as advances westward over the Bay of Campeche until the late morning hours. The winds diminish to mainly fresh category by early in the afternoon. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... A stationary front extending southwestward from the Windward Passage to northwest Jamaica and to the border of Honduras and Nicaragua. Strong high pressure is present to the west of the front. Scattered showers and isolated thunderstorms are observed north of 15N west of the front to near 82W, and from 13N to 15N west of 82W to the coast of Nicaragua. Fresh to strong northeast winds are occurring over much of the northwest Caribbean Sea, including the southern part of the Yucatan Channel. Pockets of seas in the 7-9 ft range are associated with these winds. The stationary front will weaken through tonight, and transition to a dissipating trough on Saturday morning. The fresh to strong northeast winds are expected to be north of 17N between 78W and 84W at that time, with 8 ft seas. By Saturday afternoon, the northeast winds diminish to fresh range, with seas of 6-8 ft in northeast swell. These conditions then subside by late Saturday, with seas lowering to around 5-7 ft. Strong to near gale force trades forecast within about 90 nm of the northwest will increase to minimal gale force tonight and through early on Saturday. The pressure gradient will relax on Sunday with strong ne winds forecast only within about 60 nm of the coast on Sun night, and fresh nocturnal winds expected on Monday, Tuesday and Wednesday nights. Moderate to fresh trades forecast elsewhere through Sat morning, then mostly moderate trades expected through Wednesday, with the exception of pulses of fresh northeast winds through the Windward passage. ...SW N ATLANTIC INCLUDING THE BAHAMAS... The 18Z preliminary surface analysis has a stationary front extending from 25N62W to near 20N73W. Strong high pressure is building eastward across the basin northwest of the front with the main ridge axis along 30N. The tight pressure gradient between the front and the high pressure ridge is continuing to result in strong northeast winds within 180 to 240 nm west of the front south of 23N, and including the approach to the Windward Passage as noted in a recent Ascat pass as well as in a ship observation in that vicinity. This forecast will vary little from the previous ones. The stationary front will continue to weaken through tonight, with the frontal remnants drifting back to the west across the southeast Bahamas through Saturday night. The ridging over the waters northwest of the front will translate eastward through Saturday as deep layer trough over the eastern U.S. sharpens as it shifts eastward. This will usher in a cold front across the far northwest waters Saturday night, and quickly through the remainder of the basin through late Sunday night. The front will be preceded and followed by fresh to strong winds, and seas of 8-12 ft, with the highest of these seas expected in the far northern waters. The front will lose its upper level support, and weaken to a frontal trough over the northwestern portions of the Tropical North Atlantic waters Monday into early Tuesday. Seas of 8-10 ft in northwest to north swell will linger in zone AMZ115 Monday into Tuesday, then subside to 5-7 ft Tuesday afternoon, and to 4-5 ft Wednesday. The remnant trough is forecast to drift back to the west over the far southeast waters of the SW North Atlantic basin by Tuesday afternoon. Models suggest that the next cold front will clip the far northern waters on Wednesday. Based on the latest model guidance, it appears that strong southwest winds ahead of this front will be north of 30N. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... .AMZ031...CARIBBEAN FROM 11N TO 15N BETWEEN 72W AND 80W INCLUDING COLOMBIA BASIN... Gale Warning tonight within 90 nm of coast of northwest Colombia. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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.