000 AXNT20 KNHC 121728 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Tue Dec 12 2017 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1545 UTC. ...ITCZ/MONSOON TROUGH... The monsoon trough meanders along the SW African coast of the Gulf of Guinea, before exiting the coast near 05N90W to near 06N13W. The Intertropical Convergence Zone extends from near 06N15W to 07N20W to 04.5N31W to 03N46W to the coast of far NE Brazil near 02N51W. Scattered moderate isolated strong convection is from 03.5N to 07N between 18W and 52W. ...DISCUSSION... GULF OF MEXICO... A surface ridge continues across all but the northern Gulf this morning, anchored by a 1027 mb high centered offshore of eastern Mexico near 22N96W. Gentle to moderate anticyclonic winds are noted across central and SE portions of the basin late this morning. Meanwhile fresh to strong N to NW winds are occurring across NE portions on both sides of a dry cold front moving into the N Gulf waters, where a 1524 UTC ASCAT pass showed NW winds around 25 kt across the SE Louisiana and Mississippi coastal waters. Current buoy data indicates seas across NE portions have built to 6-9 ft. The front is forecast to sweep ESE across the N half of the basin through tonight and become strung out W to E along about 24N Wednesday morning. Fresh to strong NW winds will dominate the NE Gulf behind the front. Weak high pressure will quickly replace the dissipated frontal trough through Thursday. CARIBBEAN SEA... A quasistationary frontal boundary persists across the central and SW Caribbean this morning, from near the E end of Cuba across the W coast of Jamaica to W central Panama. Morning satellite imagery suggest the front is drifting W to the S of Jamaica. Broken to overcast multi-layered clouds prevail to the W of the front from beyond the Bahamas to Panamas and Costa Rica, with active moderate to deep convection along the front from 14N to the S coast of Jamaica. Northerly winds continue to gradually diminish to the W of the front, and are assumed to have dropped to 20-25 kt to the S of 20N and between the front and 84W this morning, while 15-20 kt N winds are elsewhere W of front. Buoy 42057 between Jamaica and Honduras has fallen to 8 ft. Atlantic high pressure nosing into the E Caribbean is responsible for nudging the front W and is producing gentle to moderate E to SE tradewinds to the E of 73W. A few clusters of shallow convection are noted on satellite imagery between 68W and 72W, associated with a weak easterly perturbation. The front is forecast to meander across this general area and gradually weaken through Thursday. HISPANIOLA... Fair weather conditions prevail across the island this morning while the stationary front remains to the W across far E Cuba. Dry and fairly stable atmospheric conditions are expected across the island today, with best low level moisture expected to converge across W portions of the island this afternoon due to proximity of the front and diurnal sea breezes. ATLANTIC OCEAN... Water vapor imagery indicates a weakening narrowing middle to upper level troughing over the western North Atlc waters to near 30N70W and supports a lingering stationary front extending from near 31N60W to just NW of the Turks and Caicos to the E end of Cuba. Satellite imagery suggests very minor waves or undulations along the boundary E of 70W. Broken to overcast low and middle level clouds prevail within 120 nm NW of the front, where scattered light to moderate showers are occurring. A next broad deep layered trough is currently sweeping from the Great Lakes region into the N central Gulf states, and supporting a reinforcing cold front across the N Gulf. Weak and narrow surface ridging extends from the Gulf of Mexico NE across S Florida to near Bermuda ahead of this approaching front. A strong and broad prevail elsewhere across the central and E Atlc, centered on a 1035 mb high near 38N32W. Fresh to locally strong anticylonic flow is seen S and SW of the ridge, and generally E of 53W, where a surface trough is found drifting W. A weakening and narrow middle to upper layer trough is found along 50W and is acting to enhance an area of scattered moderate to strong convection from 16N to 30N between 45W and 50W. Farther E, a cold front is moving S and SSW across the NE Atlc and a back door fashion, extending from the SW coast of Western Sahara near 22N17W to 26N33.5W. For additional information please visit http://www.hurricanes.gov/marine $$ Stripling