868 AXNT20 KNHC 181115 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Mon Dec 18 2023 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 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 0600 UTC surface analysis and satellite imagery through 1030 UTC. ..SPECIAL FEATURES... Western Atlantic Gale Warning: A cold front extends from 984 mb low pressure located along the North Carolina coast to 24N75W to central Cuba along 77W. A warm front extends from the low to near 23N66W. A tight pressure gradient between a ridge extending SW from strong high pressure of 1046 mb near 43N50W and the area of low pressure is supporting gale-force winds over the western Atlantic waters, on both the E and W of the cold front. Seas in this area are up to 20 ft along 30-31N. A large area of 12 ft seas has been generated by this system, with seas greater than 12 ft over the waters N of 23N and W of 65W. The low will track quickly northeastward along the Atlantic coast today, with gale force winds lifting N of the area by Tue morning. The area of 12 ft seas will shift eastward, merging with another area of large swell generated from gales over the central Atlantic. Central Atlantic Gale Warning: Strong high pressure will continue to build over the north central Atlantic. This will continue to tighten the pressure gradient between this area of high pressure and a stationary front extending from 31N36W to 20N60W. This will support gale force winds over the discussion waters N of 25N between 40W and 52W today. Seas of 12 to 16 ft currently over these waters will build to near 20 ft by this evening, with seas greater than 12 ft spreading southward and westward, merging with the area of 12 ft seas generated from the gale force winds over the western Atlantic waters through the middle of the week. The strong high pressure will shift further NE and away from the area, loosening the pressure gradient across the central Atlantic waters diminishing winds below gale force Tue evening. Please read the latest NWS High Seas and Offshore Waters Forecasts issued by the National Hurricane Center at https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and https://www.nhc.noaa.gov/marine/offshores.php for more details on both Gale Warnings. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic near 08N13W, then extends westward to near 08N17W. The ITCZ continues westward from 08N17W to 07N25W to 03N35W to 03N45W. Scattered moderate isolated strong convection is noted from 09N to 14N between 20W and the coast of Africa, and from 01N to 09N between 20W and 33W. ...GULF OF MEXICO... Please read the Special Features section above about an ongoing Gale Warning. 1019 mb high pressure is centered across southern Texas. The pressure gradient between this high and the cold front across the western Atlantic is producing fresh NW to N winds over the eastern Gulf, where seas are 7 to 11 ft, and highest in the Yucatan Channel. Gentle to moderate N winds prevail W of 90W, where seas are 4 to 7 ft. Fair skies prevail across the entire basin. For the forecast, the strong low pressure that was affecting the Gulf region is now along the E coast of the U.S., with the associated cold front moving SE across the western Caribbean. Fresh NW to N winds continue across the eastern Gulf and will gradually diminish today. High pressure will dominate the weather pattern across the Gulf waters through Tue, then strengthen N of the region Wed through Thu to produce fresh to strong NE to E winds across the eastern Gulf, including the Straits of Florida. ...CARIBBEAN SEA... A cold front extends from central Cuba along 77.5W to SE Nicaragua. Fresh to strong NW to N winds prevail W of front to 10N, where seas have built to 6-9 ft. Moderate to fresh winds are E of 72W, where seas are 5 to 8 ft, highest to 8 ft in NE swell across the NE Caribbean Passages. Light to gentle winds are elsewhere. For the forecast, the cold front will move SE and reach from the E coast of Cuba to NE Costa Rica Mon evening, and from central Hispaniola to 10N80W Wed evening before dissipating across the Caribbean. Fresh to strong northerly winds and seas to 9 ft are expected in the wake of the front through Wed. High pressure will build SE across the western Atlantic Wed night through Fri to produce fresh to strong NE winds across much of the Caribbean basin. ...ATLANTIC OCEAN... Please read the Special Features section for more on the Storm and Gale Warnings. A stationary front extends southwestward from near 31N36W to 20N60W, then continues as a warm front to the 984 mb low center along the east coast. A cold front extends from that low through central Cuba then into the NW Caribbean. Scattered moderate isolated strong convection is N of 20N within 180 nm E of the cold front, and from 18N to 30N between 40W and 46W. 1046 mb high pressure centered across the NW Atlantic is creating a strong pressure gradient N of the stationary front, and producing a very large area of strong to gale-force winds N of this stationary front to the cold front along about 72W. High seas of 10 to 16 ft prevail there. Outside of this areas, fresh to locally strong winds are found N of 18N and E of 42W, where seas are 7 to 9 ft. Gentle to moderate winds prevail elsewhere S of 18N across the tropical Atlantic, with seas of 5 to 7 ft. For the forecast W of 55W, a western Atlantic cold front extends through 31N73W to 24N75W to eastern Cuba along 77W. Gales ahead of the front will persist through Tue while gales behind the front are expected to move N of the area this morning. The front is expected to reach from 31N69W to the E coast of Cuba by Mon evening, from 31N61W to the N coast of Hispaniola near 19N70W by Wed evening, and from 28N55W to eastern Hispaniola by Thu evening. Strong high pressure will build into the western Atlantic behind the front Tue night through early Thu to produce fresh to strong winds. $$ Stripling