000 AXNT20 KNHC 172122 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Thu Nov 18 2021 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 1800 UTC surface analysis and satellite imagery through 2000 UTC. ...SPECIAL FEATURES... Gulf of Mexico Gale Warning: Gale-force NW-N winds will develop offshore of Veracruz Fri afternoon behind a cold front that will move through the basin. Seas will build to around 12 ft with the gale-force winds. Conditions should diminish below gale-force by Fri evening. Please see the latest NWS High Seas Forecast issued by the National Hurricane Center at website://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more information. ...MONSOON TROUGH/ITCZ... The monsoon trough reaches the Atlantic through the coast of Guinea-Bissau near 12N16W to 09N17W. The ITCZ extends from 09N17W to 05N22W to 07N31W to 04N45W. Scattered moderate and isolated strong convection is noted from the equator to 11N between 25W and 41W. GULF OF MEXICO... Please see the Special Features section above for details on a Gale Warning in effect near Veracruz, Mexico. A ridge of high pressure extends across the southeastern United States with return flow across the basin. Moderate to fresh E-SE winds are found in the eastern Gulf, strongest in the southeast Gulf through the Straits of Florida, with gentle to moderate SE-S winds elsewhere. Seas are 3 to 5 ft across the northern half of the Gulf, with 4 to 6 ft seas in the southeast Gulf, except to 7 ft through the Straits of Florida, and 2 to 4 ft in the southwest Gulf. Deep tropical moisture moving in from the northwest Caribbean is allowing for scattered showers and thunderstorms embedded within these easterly winds across the southeast and south-central Gulf. For the forecast, a cold front moving into coastal Texas will enter the northwest Gulf early Thu. Strong winds and rough seas will follow the front over the western Gulf, reaching gale force off Veracruz Fri. The front will stall from near Tampa Bay, Florida to 24N95W to Veracruz by Sat, then start to dissipate. Looking ahead, another front will move into the northwest Gulf early Mon, and reach from southwest Florida to the southwest Gulf by late Mon night. CARIBBEAN SEA... A surface trough extends from just offshore of the Yucatan Peninsula extending from near Cozumel, Mexico to the Gulf of Honduras. This trough combined with deep tropical moisture and upper-level divergence are producing numerous moderate to isolated strong convection north of 17N, west of 80W. The rest of the Caribbean is fairly dry, except for scattered moderate convection noted just off the coasts of Honduras, Nicaragua, Costa Rica, and northern Panama, in association with localized land breezes as well as the eastern extension of the Pacific monsoon trough along 10N. High pressure north of the Greater Antilles and lower pressure across South America is translating to a tight pressure gradient over the basin, and thus moderate to fresh winds encompass most of the basin, fresh to strong in the central Caribbean from southwest of the Dominican Republic to offshore of Colombia. Seas of 6 to 9 ft dominate the central Caribbean, highest northwest of Colombia. Seas of 4 to 7 ft prevail in the eastern Caribbean with 3 to 5 ft in the western Caribbean. For the forecast, winds and seas will diminish through Fri as high pressure north of the area shifts east, ahead of a cold front moving into the Gulf of Mexico and western Atlantic. Winds and seas further diminish early next week, ahead of a second cold front moving through the Gulf late Mon and Mon night. ATLANTIC OCEAN... A cold front enters the tropical Atlantic near 31N51W and extends to 25N68W, where it transitions to a shear line that continues across the southeast Bahamas. No significant convection is occurring along this boundary. Fresh to locally strong winds are occurring within about 180 nm north-northwest of the boundary, with 5 to 7 ft seas across the area north of the boundary, locally to 8 ft near the strong winds. Farther east, a 1011 mb low pressure is near 25N31W. A weakening surface trough associated with the low pressure extends from the low to 23N41W. Scattered moderate convection is noted from 24N to 30.5N between 26W and 33W. Fresh to locally strong mainly easterly winds are noted northeast of the low between 28W and 35W, along with 7 to 10 ft seas. Aside from the winds near the cold front and low pressure, to the west of 40W, mainly moderate winds prevail except fresh winds north of the Lesser Antilles to 22N, highest through the Caribbean passages. Gentle to moderate winds are occurring elsewhere. Seas of 5 to 8 ft prevail elsewhere across the open Atlantic. The Cumbre Vieja volcano, on the island of La Palma in the Canary Islands, has been erupting since 19 September 2021. Marine and aviation interests should monitor this ongoing situation by reading the Volcanic Ash Advisory issued by Meteo-France, at http://vaac.meteo.fr/volcanoes/la-palma/. For the forecast, high pressure north of the area and the shear line will shift east tonight, ahead of cold front moving off the northeast Florida coast. The front will stall from Bermuda to central Florida Sat, then lift north again Sun ahead of a stronger front moving off the northeast Florida coast late Mon. The second front will reach from Bermuda to eastern Cuba by Tue night. $$ Lewitsky