000 AGXX40 KNHC 301856 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 256 PM EDT Sat Sep 30 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 middle to upper level low continues over the E central Gulf near 27N86W and currently drifting W attm but forecast to shift SW and across the Yucatan through Mon. Deep tropical moisture continues to feed N from the NW Carib into the Gulf E of the low and then NE across central FL. Inverted llvl troffing is found from the Gulf of Honduras NNE into the E Gulf with moderate to fresh trades forcing scattered showers and thunderstorms across the SE Gulf to just S of Tampa Bay. A surface trough forecast by GFS is verified by recent ASCAT pass across the SW Gulf from near Tampico SSE and offshore of coast to Laguna de Terminos in the E Bay of Campeche, with NW winds 15-25 kt to W of trough between Cabo Rojo and Coatzacoalcos. Seas there estimated at 5-8 ft. As the upper low shifts SW during the next 48 hours the surface trough across NW Carib will shift W across the Yucatan and reinforce the broad troffing across the SW Gulf, while the winds diminish W of the trough along the Mexican coast. Associated weather will follow the upper low. Strong high pressure is forecast to build across the NE Gulf this evening and tonight behind a stationary front, increasing winds to strong N of the front which will spread across the waters N of 27N/28N through early Monday, then will continue to expand across the waters N of 23N E of 91W by mid-week. Seas will build to 8 to 11 ft through early next week as a result. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... The deep layered low in the E central Gulf of Mexico continues to advect deep tropical moisture across the waters W of 80W. This pattern is forecast to persist through the weekend as the low shifts SW and maintain moist unstable environment across NW portions. A tropical wave over the eastern Caribbean extending SSW from the Mona Passage to NW Venezuela continues to interact with a TUTT low retrograding slowly WSW across the Dominican Republic with widespread showers and scattered thunderstorm activity over the eastern Caribbean extending E and SE across the Lesser Antilles. This tropical wave and accompanying upper low will move westward to the central Caribbean through the weekend, then the western Caribbean early next week, bringing accompanying unsettled weather. Moderate to fresh trades in the central Caribbean between these two areas will diminish as a frontal system intrudes on the SW N Atlantic N of the area weakening the pressure gradient. Moderate trades will dominate the entire basin for the early part of the upcoming week into mid-week, except expect gentle to moderate southerly flow in the SW Caribbean S of the monsoon trough which will continue to be lifted slightly northward extending from NW Colombia to eastern Nicaragua. ...SW N ATLANTIC INCLUDING THE BAHAMAS... A surface trough extends across the northern portion from near 31N76W to weak low pressure over central Florida between Orlando and Cape Canaveral. Scattered showers and thunderstorms conitnue across this area N of the Bahamas between FL and 71W under upper level diffluence. Mainly gentle to moderate easterly flow dominates the basin, except locally fresh winds N of Hispaniola. Seas are mainly 4 to 7 ft, except 1 to 3 ft inside protected areas SW and W of the Bahamas. Nly swell from Maria is propagating through the NE and E waters and is a bit underforecast by models, 1-2 ft, but WW3 timing looks good attm. A cold front is forecast to sag southward into the NW portion late this afternoon and tonight with fresh to strong NE flow behind is as high pressure builds in. Seas will quickly build to 8 to 12 ft as a result. The front will extend from near Bermuda to 30N70W to E central Florida by Sunday evening, then will gradually weaken from near 30N65W to the northern Bahamas early next week while high pressure continues to build southward. Fresh to strong NE flow will persist across the NW half of the basin, with moderate to fresh trades across the SE half through mid- week. The persistent NE to ENE fetch will maintain 8 to 11 ft seas, except 5 to 7 ft across the SE half of the basin. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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 Stripling. National Hurricane Center.