marine weather discussion NWS National Hurricane Center Miami FL 242 PM EST Tue Nov 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...
A rather complex weather regime is setting up over much of the Gulf as for the short term as low pressure of 1012 mb has developed this morning near 28n85w with an associated cold front extending from its SW to just N of the NW Yucatan Peninsula and a warm front that extends from the low E to inland W central Florida near Tampa. A deep upper trough over the central Gulf supports this frontal system and low. A pre-frontal trough is analyzed from near 27n84w to 23n86w. Latest satellite imagery shows numerous showers and thunderstorms over much of the NE Gulf to the N of the warm frontal boundary. The low will rapidly track east-northeastward across N central Florida Wednesday night through Thursday, and push a cold front across the area through Saturday. Gale conditions under NW to N flow will begin along the coast of Mexico near Veracruz beginning late on Wednesday morning or early in the afternoon. Latest wave model guidance suggests that combined seas will peak to a maximum of around 14 ft with these gale force conditions on Thursday before subsiding to around 10 ft Thursday night and to less than 8 ft early on Friday as high pressure settles back over the entire area. The related 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 he se part of the Gulf where seas will be higher in the 3-5 ft range due to a NW swell.
...Caribbean Sea and tropical N Atlantic from 07n to 19n between 55w and 64w...
The 1506z ascat pass indicates that the earlier fresh to strong NE winds that were across the Windward Passage have diminished to gentle to moderate NE-E winds. Moderate to locally fresh E-se winds are over the far S central and se portions of the basin, while gentle to moderate E-se winds are elsewhere, with the exception of NE-E winds in the gentle range over the western Caribbean. The latest surface analysis has a trough extending from just se of Jamaica to near 11n79w. The same 1506z ascat pass detected a NE to se wind shift of mainly gentle winds across the trough axis. In addition, latest visible satellite imagery shows low-level cloud motion from NE to se across the axis of the trough. Isolated showers are along and near the trough. The trough will linger over the west-central Caribbean through at least Thursday. Winds will diminish over the S central and se potion 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 Saturday along with Max combined seas of 6 or 7 ft. These winds then diminish on some on Sunday.
...SW N Atlantic including the Bahamas...
A complex weather scenario is setting up across the area. As of 18z, a stationary front extends from near 28n65w to 28n72w where it becomes a warm front to inland Florida near Cape Canaveral. The 1506z ascat pass highlighted a swath of E 20-25 kt winds N of the stationary and warm front between 70w-76w. Latest NWS Doppler radar display shows a large patch of scattered to numerous showers and thunderstorms lifting quickly northward over the NW waters to the N of the NW Bahamas. A surface trough is located from just NE of the eastern tip of the Dominican Republic to near 22n65w. The weather pattern through the end of the week will be rather fast pace as features in the upper levels progress quickly from W to E over the area.
The warm front will lift northward through Wednesday. A low pressure system over the eastern Gulf of Mexico will track east- northeastward towards N central Florida Wednesday night through Thursday. The low will lift N of the NW portion on Friday 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 near 29n74w by early on Wednesday, and quickly track northeastward to just NE of the forecast waters by early on Thursday. Gale force winds are becoming more likely with southerly flow to the E and se of the low beginning on Wednesday 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 Friday night. The aforementioned surface trough from just NE of Hispaniola to near 22n65w will drift NW today and tonight and merge with the frontal boundary associated with the low that forms near 29n74w.
.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 Wed into Wed night. Gale conditions possible Wed night into Thu.
.Caribbean Sea and tropical N Atlantic from 07n to 19n between 55w and 64w... none.
.SW N Atlantic including the Bahamas... None.
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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.