845 AXNT20 KNHC 221058 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Mon Nov 22 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 0600 UTC surface analysis and satellite imagery through 1030 UTC. ...SPECIAL FEATURES... Atlantic Gale Warning: A pair of strong cold fronts will move off the coast of northeast Florida, today and tonight, respectively. The fronts will merge Tue as they advance eastward. The merged cold front will reach from near Bermuda to eastern Cuba late on Tue. Fresh to near gale force S to SW winds will develop tonight east of the first front. Then, fresh to near gale force N winds and building seas are forecast behind the reinforcing front beginning early Tue. Gale force N winds are expected just behind the front, N of 29N and E of 75W, beginning late Tue morning and lasting until early Tue evening. Seas are forecast to build to 10-14 ft with these winds. Please refer to the latest High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coast of Guinea-Bissau near 12N16W to 08N19W. The ITCZ continues from 08N19W to 05N26W to 05N39W to 01N50W. Scattered moderate to strong convection is within 240 nm either side of the ITCZ from 00N to 09N between 25W and 43W. GULF OF MEXICO... A cold front has moved into the NW Gulf and extends from Lake Charles, Louisiana to Corpus Christi, Texas. Fresh N winds are behind the front. Elsewhere, a 1019 mb high pressure is centered near 29N87W. Gentle anticyclonic winds prevail over much of the Gulf with seas of 3 to 4 ft. Isolated moderate thunderstorms are noted in the southern Bay of Campeche, south of 20N. For the forecast, the cold front extending from Lake Charles to Corpus Christi will move SE, exiting the Gulf on Tue. In the meantime, another cold front will form this morning over the eastern Gulf, ahead of the trailing front. The leading front will move SE, exiting the Gulf by this evening. Fresh to strong northerly winds are expected behind the fronts, mainly offshore Tampico, Mexico late today, and over the northeast Gulf tonight into early Tue. High pressure is forecast to build in behind the front. Fresh southerly return flow will set up across the NW Gulf by the middle of the week ahead of the next cold front forecast to reach the Gulf waters by Thu night. Strong to near gale force winds are likely behind the front over the far western Gulf Thu night and Fri, with gale force winds possible Fri off the coast of Tampico. CARIBBEAN SEA... Broad mid to upper-level anticyclonic wind flow covers the Caribbean Sea. Water vapor imagery depicts weak subsidence, resulting in rather stable atmospheric conditions over the central and eastern Caribbean. GOES-16 satellite imagery indicated a trough in the east-central Gulf south of the Mona Passage from 17N68W to 09N69W. Earlier thunderstorms associated with a weak trough in the central Caribbean have dissipated. Scattered moderate convection is noted in the SW Caribbean, S of 14.5N and W of 76W with the influence of the monsoon trough. Isolated tstorms are also noted in the Gulf of Honduras and near Cozumel. Moderate wind speeds are occurring over the Caribbean south of 17N, with fresh speeds near the coast of Colombia. Light to gentle variable winds are over the NW Caribbean. Seas in the western Caribbean are 1-3 ft with 3-5 ft in the central and eastern basin, and up to 6 ft near the coast of Colombia. For the forecast, gentle to moderate trades will prevail across much of the Caribbean Sea through today. A cold front will reach the Yucatan Channel late this afternoon or evening. The cold front will extend from eastern Cuba to eastern Honduras by late Tue as a reinforcing front reaches the Yucatan Channel. Fresh N to NE winds and building seas are expected across the western Caribbean through Thu, with locally strong NE winds in the Windward and Mona Passages. Moderate northerly swell will affect the NE Caribbean passages beginning Thu night and Fri. ATLANTIC OCEAN... Please see the Special Features section above for details regarding an upcoming gale event. Upper-level diffluence over the western Atlantic is enhancing scattered moderate convection from 26N-30N between 69W-80W near a weakening shear line boundary. Isolated thunderstorms are also noted across the Straits of Florida. Moderate easterly winds are noted in most of the western Atlantic with seas 5-8 ft. In the central Atlantic, two troughs are noted from 27N55W to 21N56W and along 64W from 21N-26N. Showers have diminished near these features during the last several hours. Moderate winds are along these two troughs, with gentle to moderate winds prevailing across the central Atlantic. However, ridging north of the area is increasing the pressure gradient north of 28N between 47W-63W, where fresh winds are likely occurring. Seas range from 5-8 ft, except 8-10 ft north of 28N between 48W-64W. A cold front extends across the eastern and central Atlantic from 31N16W through the Canary Islands to 21N29W, then stationary to 20N47W. Isolated moderate convection is along and east of the front, from 24N-29N. Moderate westerly winds are behind the front, north of 26N. The Cumbre Vieja volcano, on the island of La Palma in the Canary Islands, has been erupting since 19 September 2021. Medium ash concentration is in the vicinity of the volcano, while lower concentration is elsewhere. 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, a strong cold front will move off the coast of northeast Florida by midday today. A reinforcing cold front will then move off the northeast Florida coast late tonight. The fronts will merge on Tue as they advance eastward. The cold front will reach from near Bermuda to eastern Cuba late on Tue. Fresh to near gale force S to SW winds will develop tonight east of the first front. Then, fresh to near gale force N winds and building seas are forecast behind the reinforcing front beginning early Tue. Gale force N winds are expected just behind the front, N of 29N between 69W-75W on Tue. The front will be accompanied by scattered showers and thunderstorms. In the wake of the front, high pressure will build in off the coast of Georgia and northern Florida on Thu. $$ Hagen