000 AXNT20 KNHC 110425 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Sat Dec 11 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 0000 UTC surface analysis and satellite imagery through 0425 UTC. ...MONSOON TROUGH/ITCZ... The monsoon trough remains mostly confined to the African continent, reaching the coast of Guinea near 10N13W and extending to 08N17W. The ITCZ begins near 08N17W and extends westward to 04N30W and then to the coast of Amapa near 02N50W. Scattered moderate to isolated strong convection is observed from 02N to 09N and E of 27W. GULF OF MEXICO... The Gulf of Mexico is in the southwestern periphery of an expansive 1029 mb high pressure system located to the SE of Nova Scotia in the NW Atlantic. Dry continental air continues to dominate the region, maintaining tranquil weather conditions. The pressure gradient between the subtropical ridge and lower pressures over Texas and northern Mexico result in moderate to fresh southerly winds, especially W of 87W. A recent scatterometer satellite pass even showed a small area of strong southerly winds in the NW Gulf. Seas of 4-7 ft prevail in the central and western Gulf, while seas of 2-4 ft are prevalent elsewhere. The highest seas are occurring in the NW Gulf. For the forecast, areas of marine fog will lower visibility to less than one nm tonight and Sat night along the NE Gulf. A high pressure ridge extending from the Atlantic to the central Gulf will gradually shift eastward through Sat afternoon in response to a strong cold front that will move over the NW Gulf on Sat. Moderate to fresh southerly return flow will set-up across the western Gulf tonight ahead of the front. Fresh to strong northerly winds and building seas are expected in the wake of the front through Sat night. The front will weaken as it reaches from central Florida to the SW Gulf Sun and dissipate by Mon. Fresh to strong east winds will spread westward through the Straits of Florida and to the eastern Gulf S of 26N Mon through Tue night along with building seas. CARIBBEAN SEA... The tight pressure gradient due to the strong ridge north of the Greater Antilles and lower pressures over northern South America result in strong to near gale-force trades across the south- central Caribbean Sea as shown in a recent scatterometer satellite pass. The strongest winds are occurring offshore NW Colombia. Fresh to locally strong trades are present in the north-central Caribbean Sea, with the strongest winds observed offshore southern Hispaniola and in the Windward Passage. Seas of 7-10 ft prevail in the central Caribbean Sea, with the highest seas occurring offshore NW Colombia. The rest of the basin enjoys tranquil weather conditions, moderate to locally fresh trades and 3-7 ft seas. For the forecast, the aforementioned pressure gradient will continue to support fresh to strong easterly trades over the south-central Caribbean through the weekend. Moderate to fresh trades will prevail elsewhere. High pressure will continue to strengthen over the western Atlantic through the forecast period, resulting in pulsing fresh to locally strong northeast winds in the Windward Passage, the lee of Cuba and south of Hispaniola through Wed night. ATLANTIC OCEAN... High pressure dominates most of the tropical Atlantic. A strong subtropical ridge is positioned off Nova Scotia in the NW Atlantic, while a second robust subtropical ridge is anchored off the Azores in the NE Atlantic. The pressure gradient between the subtropical ridges and lower pressures over NW Africa and the deep tropics result in fresh to strong easterlies, mainly south of 25N. Strong E-NE winds are noted at the entrance of the Windward Passage. The strongest winds are occurring off the Morocco coast and in the waters surrounding the Canary Islands. Seas of 8-12 ft are found E of 50W, with the highest seas occurring offshore Morocco. A weak shear line extends from 31N55W to 29N71W, passing about 200 nm south of Bermuda. A recent scatterometer satellite pass depict a small area of fresh E winds north of the shear line. Seas of 4-8 ft are present W of 60W. A surface trough is analyzed along 51W, extending from 09N to 21N. Satellite imagery show a few showers and isolated thunderstorms near the trough axis, especially S of 13N. The rest of the tropical Atlantic enjoys fairly tranquil weather conditions, moderate or weaker winds and 5-8 ft seas. For the forecast west of 65W, high pressure will continue to build across the region producing moderate to fresh NE to E winds S of 20N, and mainly gentle to moderate winds N of 20N through Sat night. The next cold front will move off the northeast Florida coast Sun, and reach from near 31N65W to South florida by Sun night. This front is forecast to dissipate over the southeastern waters on Mon. High pressure behind the front will bring fresh to strong northeast to east winds mainly across the waters south of 27N by Mon night. These conditions are expected to last through Tue night. The Cumbre Vieja volcano, on the island of La Palma in the Canary Islands, has been erupting since 19 September 2021. Low ash concentrations are expected in the vicinity of the volcano with very low concentrations to the southwest. 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/. $$ DELGADO