marine weather discussion...corrected NWS National Hurricane Center Miami FL 315 am EST Sat Dec 10 2016
Corrected Gulf of Mexico section
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...corrected
Model preference: global model consensus. High confidence then medium confidence next week.
The 06z surface analysis shows the former cold front as a stationary front that extends from western Cuba southwest to inland the northern Yucatan Peninsula. Strong high pressure present across the Gulf is building eastward. The associated ridge axis noses southward across eastern Mexico, and to southeast Mexico. The resultant tight pressure gradient is keeping gale force northwest winds of 30-40 kt in the far southwest portion of the Gulf within 60 nm in zone gmz023 within 60 nm of Veracruz with large seas of 10-17 ft there. The 0340z ascat pass highlighted a large swath of strong northeast winds from 21n to 25n between 87w and 92w, while fresh northeast winds were noted north of 25n. Recent altimeter data revealed quite high seas of 9-14 ft within the area of strong northeast winds and 8-10 ft within the area of fresh northeast winds between 88w and 92w. Both buoys and the 0340z ascat pass show fresh to strong northeast winds elsewhere, with the more concentrated area of strong northeast winds south of 26n west of 92w. Seas are in the range of 8-12 ft elsewhere south of 28n west of 85w, and 4-6 ft remainder of area, except for 7-10 ft seas south of 25n east of 85w, including the entrance to the Yucatan Channel and Straits of Florida.
Water vapor imagery shows ample upper-level moisture streaming eastward across much of the central and eastern Gulf in broad upper level southwest flow. Upper-level jet stream energy riding along this flow is helping to trigger off scattered showers and possible isolated thunderstorms over much of the eastern Gulf zones gmz015 and gmz021 as well as the southeast portion of zone gmz019. This activity will continue through Sunday evening.
The strong high pressure will continue to shift eastward and weaken through early on Monday. The culprit tight pressure gradient producing the gale force winds in the far southwest Gulf will slacken enough this afternoon to allow for the gale winds to diminish to just below gale force. The seas in the southwest Gulf will lower to around 8-12 ft tonight, and to 6-8 ft on Sunday as the gradient slackens further. By Monday a weaker gradient in place will allow for seas to lower to 3-4 ft west of about 86w, and 2-3 ft east of 86w. By late Monday night, seas are expected to be 2-3 ft throughout, except for 3-5 ft seas in the approach to the Yucatan Channel, and in the Yucatan Channel.
Models are better agreement that a weak cold front will approach the northern Gulf on Wednesday, and move into the far northern coast waters late Wednesday.
...Caribbean Sea and tropical N Atlantic from 07n to 19n between 55w and 64w...
Model preference: global model consensus. High confidence.
The 0156 ascat pass showed a swath of fresh northeast winds to the south of Hispaniola and Jamaica, and also through the Windward Passage where a ship is currently reporting similar winds. A small pocket of strong northeast to east winds is along the coast of Colombia. Seas remain in the 7 to 9 ft range over the south central Caribbean. Both buoy and ascat data show moderate to fresh northeast to east winds elsewhere, with seas in the 5-7 ft range, except for 3 to 4 ft west of 79w and higher seas of 5-6 ft in the Windward Passage.
A well-defined surface trough, resembling an easterly wave, is analyzed at 06z along a position from just south of Haiti to the northwest coast of Colombia. It is moving west at about 15 kt. A tight gradient in the wake of the trough is helping to contribute to the aforementioned fresh northeast winds over the central Caribbean. Scattered showers and thunderstorms are observed east of the trough to 65w. This activity is being further enhanced by an upper level diffluent flow pattern occurring to the east of an upper-level trough just to the west of surface trough. The surface trough will reach near 77w/78w tonight, near 79w Sunday night, and move over the western Caribbean late Sunday night and Monday before it moves inland Central America Monday night and Tuesday.
The cold front that moved across the Gulf of Mexico yesterday has stalled across the Yucatan Channel and extends northeastward over western Cuba. The front will slowly become diffuse through Sunday as the strong high pressure behind it slides eastward. The fresh northeast winds in the central Caribbean will become mostly strong, and expand in coverage through Monday night, then diminish on Tuesday. Strong northeast to east trades are expected to materialize across the tropical North Atlantic zone amz127 Sunday night through most of Tuesday. Seas are expected to build to around 11 or 12 ft in the central Caribbean zone amz031 Sunday through Monday before subsiding thereafter. Seas are forecast to build to 8-10 ft in the tropical North Atlantic zone Monday and Monday night before subsiding some on Tuesday.
...SW N Atlantic including the Bahamas...
Model preference: global model consensus. High confidence.
Strong high pressure is surging eastward from the Carolinas into the western Atlantic behind a slow moving cold front currently extending from near 31n64w to 28n70w to 26n76w where it becomes stationary to The Straits of Florida and to along northwest Cuba. The front will move eastward and reach to roughly along 26n by this evening, while the stationary portion becomes diffuse. The cold front portion will will then begin to dissipate Sunday through late Sunday night. The strong high pressure behind the front will then shift eastward to the eastern part of the basin by Tuesday in response to a weak cold front that approaches the southeast U.S. Strong northeast winds south of the ridge, and to the north of the front will encompass the area from 24n to 27n with seas in the 6-9 ft range through the northern Bahamas by early this evening. As the high pressure shifts eastward, these conditions will expand to much of the area south of 28n through Sunday night, then shrink in coverage through Tuesday as the pressure gradient slackens. Seas to 8 ft will persist through Monday east of the Bahamas, then be confined to zone amz127 on Tuesday as seas subside to 4-5 ft elsewhere east of the Bahamas, and to 2-3 ft southwest of the Bahamas. The previously mentioned cold front is expected to brush the far northern waters Monday through Tuesday night. Presently, model guidance highlights mainly fresh south to southwest winds ahead of this front, and gentle to moderate west to northwest winds behind it becoming light and variable Tuesday night and Wednesday. Seas of 5-7 ft are expected east of the front within the fresh to south to southwest winds, and 4-5 ft behind the front.
.Warnings...Any changes impacting coastal NWS offices will be coordinated through AWIPS ii collaboration chat, or by telephone:
.Gulf of Mexico... .gmz023...SW Gulf S of 22n W of 94w... Gale Warning through this afternoon.
.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.Hurricanes.Gov/marine
.Forecaster Aguirre. National Hurricane Center.