AGXX40 KNHC 220750

Marine Weather Discussion
NWS National Hurricane Center Miami FL
250 AM EST Wed Nov 22 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


A rather complex weather pattern is noted over the gulf waters. A 1011 mb low pressure has developed over the NW gulf near 27N92W while a cold front is approaching to the coast of Texas. Another 1012 mb low pressure is over the NE gulf with a stationary front extending eastward across northern Florida. A vigorous short-wave trough over the NW gulf supports this weather pattern. Doppler Radar shows scattered showers and thunderstorms over the NW gulf. The low over the NE gulf will rapidly track east-northeastward across N central Florida into the Atlantic Ocean today. The cold front currently approaching the coast of Texas will merge with the second low pressure located over the NW gulf. Gale conditions are expected this morning in the wake of the front across the west-central gulf, spreading across the SW Gulf early this afternoon. Wave model guidance suggests that combined seas will peak to a maximum of around 14 ft with these gale force conditions tonight before subsiding to around 10 ft early Thursday night and to less than 8 ft early on Friday as high pressure settles back over the entire area. The related pressure gradient will bring generally moderate to fresh northerly flow through Friday night and light to gentle northerly flow Saturday through Sunday night, except for light anticyclonic flow over the central gulf on Saturday and over the NW gulf on Sunday. Seas will lower to 2-3 ft over the entire waters on Saturday, except for the SE part of the gulf where seas will be higher in the 3-5 ft range due to a NW swell.


A surface trough persists across the basin and now extends from eastern Cuba near 21N78W to 17N81W to 11N80W. Isolated showers are along and near the trough forecast to linger over the west- central Caribbean through at least Friday. Scatterometer data detected a NE to SE wind shift of mainly gentle winds across the trough axis, with the exception of moderate northerly winds just off the coast of Nicaragua. Moderate to locally fresh easterly winds are noted over the eastern Caribbean, with mainly fresh winds off the coast of Venezuela, including also the ABC Islands. Winds will diminish over the S central and SE portion late this week as high pressure N of the area weakens in response to the developing low pressure along the east coast of the United States. Seas will be quite low, in the 2-4 ft range for the next few days. The weak pressure gradient should remain in place over the Caribbean until Thursday, when a cold front will enter the NW Caribbean from the Gulf of Mexico. Model guidance indicates that the front will then stall and weaken over the NW Caribbean Friday. The pressure gradient between building high pressure over Central America and the frontal boundary should bring an increase in northerly winds of mostly 20 kt with possible pockets of 25 kt within about 120 nm off the Nicaragua coast Thursday night through Sunday night along with max combined seas of 6 or 7 ft.


A ridge dominates the waters NE of the Bahamas, while lower pressures are noted between the Bahamas and Cuba, and also over Florida and regional Atlantic waters due to the presence of a couple of surface troughs. A stationary front, extending from a 1012 mb low pressure located over the NE Gulf of Mexico, crosses the NW portion of the forecast area. Under this weather pattern, scatterometer data show an area of fresh to strong E to SE winds across the waters N of 22N and E of a line from 31N75W to 22N72W. As previously mentioned, the low pressure situated over the NE Gulf of Mexico will rapidly track east-northeastward across N central Florida into the Atlantic Ocean today dragging a cold front across the NW and central waters through Saturday night. Scattered to numerous showers and thunderstorms with gusty winds are expected with both the low and the cold front. Another low will form over the NE waters today, and quickly track northeastward crossing just SE of Bermuda tonight into early Thu morning. Strong to near gale force winds are expected with southerly flow to the E and SE of the low beginning later today as the gradient between it and strong central Atlantic high pressure tightens. This low will push a weak frontal boundary across the central and eastern waters through Thu. Another low pressure system will move across Florida into the SW N Atlantic by Fri evening. The associated cold front will move across the forecast area through Sun.


.WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone:

.GMZ017...W CENTRAL GULF FROM 22N TO 26N W OF 94W... Gale Warning today.
.GMZ023...SW GULF S OF 22N W OF 94W... Gale Warning today into Thu.




*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 GR. National Hurricane Center.