000 AXNT20 KNHC 071709 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Thu Oct 7 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 1200 UTC surface analysis and satellite imagery through 1705 UTC. ...TROPICAL WAVES... An Atlantic tropical wave has its axis along 31W, south of 16N and it is moving W around 15 knots. The convection near the southern portion of the wave is described in the Monsoon Trough/ITCZ section. The northern portion of the wave is surrounded by dry Saharan air resulting in no deep convection N of 08N. Another Atlantic tropical wave has its axis along 56W, south of 19N and it is moving W around 15 knots. Divergence aloft is interacting with the wave and another surface trough nearby causing a large area of scattered showers and isolated thunderstorms, mainly from 09N to 15N and between 53W and 62W. A Caribbean tropical wave has its axis along 88W, south of 21N, extending from the N Yucatan through W Central America and into the E Pacific. The wave is moving W at 10-15 knots. Scattered moderate convection is noted near the trough axis in the Gulf of Honduras, mainly within 60 nm of Belize. Most of the wave is over the E Pacific. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean through the southern coast of Senegal near 13N17W to 08N19W. The ITCZ then continues from 08N19W to 06N25W and to 06N31W. Another segment of the ITCZ is found from 05N32W to 04N40W and to the coast of NE Brazil near 01S48W. Numerous moderate to isolated strong convection is observed within 240 nm of the ITCZ between 16W and 40W. GULF OF MEXICO... The main feature of interest in the Gulf of Mexico remains a weak stationary front that enters the basin near the Florida-Alabama border and meanders S-SW to the central Bay of Campeche. A few showers and isolated thunderstorms are seen on satellite imagery near the frontal boundary, especially in the central Bay of Campeche. Scattered moderate convection is also noted in the E Bay of Campeche and within 90 nm of the N Yucatan coast and the Big Bend area of Florida. The rest of the basin enjoys of fairly tranquil weather conditions, especially the NW and W Gulf thanks to continental dry air behind the stationary front. A weak pressure gradient allows for a benign wind pattern across the Gulf, with gentle to moderate cyclonic winds prevailing. The exception is the W Bay of Campeche where moderate to locally fresh N-NW winds are found, mainly within 60 nm of the coast of Veracruz. Seas of 2-4 ft are found in the Bay of Campeche and SE Gulf, especially in the Florida Straits, while 1-2 ft are prevalent elsewhere. For the forecast, the previously mentioned stationary front will meander today before drifting NW and gradually dissipating through Fri. High pressure over central and southern Mexico will support moderate to locally fresh northerly winds over Veracruz adjacent waters through Fri early in the evening. Weak high pressure will build across the E half of the basin late this weekend into early next week, and support moderate to locally fresh return flow W of 90W Sun through Mon. CARIBBEAN SEA... An upper level trough extends across Hispaniola and Puerto Rico to the ABC islands, enhancing scattered moderate to isolated strong convection over the E Caribbean, with the strongest convection occurring near the Windward Islands. Scattered moderate to isolated strong convection is also observed in the SW Caribbean due to abundant moisture and enhancement from the eastern extension of the E Pacific monsoon trough that enters the basin through the coast of Costa Rica to a 1009 mb low near 10N77W to NW Colombia. The convection extends from the coast of Nicaragua to NW Colombia, mainly within 155 nm of the coasts of the countries in the region. A drier environment is prevalent elsewhere in the Caribbean Sea, resulting in fairly tranquil weather conditions. A modest pressure gradient between a 1023 mb Bermuda High and lower pressures in South America and the monsoon trough in the SW Caribbean Sea results in a large area of fresh to strong trades in the central and SW Caribbean, especially from 71W to 84W and between 18N near the coasts of Hispaniola and Jamaica to 10N near the coasts of N Colombia and Nicaragua. A recent scatterometer satellite pass indicate that the strongest winds are mostly confined from 11N to 14N and between 74W and 80W. The rest of the Caribbean Sea experiences mainly gentle to moderate trades. Seas of 8-10 ft are found in the south- central Caribbean, while 5-8 ft are present in the north- central, E and SW Caribbean. Seas of 3-5 ft are prevalent in the NW Caribbean and Gulf of Honduras. For the forecast, fresh to locally strong trade winds will continue across the majority of central and SW Caribbean today and tonight behind a tropical wave moving across Honduras. A tropical wave will move across the tropical Atlantic waters today through early Fri and weaken as it enters the E Caribbean Fri. A low level disturbance accompanied by strong winds and very active weather will enter the tropical Atlantic waters early Fri and reach the central Lesser Antilles Fri morning before weakening as it moves westward across the E Caribbean Fri through Sat. High pressure will build N of the area late in the weekend and support mainly moderate trades over the eastern half of the basin Sun through Mon night. ATLANTIC OCEAN... A 1016 mb low pressure off the South Carolina coast is producing a large area of showers and thunderstorms well to the E of the center due to strong wind shear. The convection is mainly confined to the N of 29N and between 70W and 78W. The National Hurricane Center is tracking this system for possible tropical development over the next few days and assesses a low chance of development during the next 48 hours. Please visit the latest Tropical Weather Outlook at hurricanes.gov for more details. A surface trough extends from 28N53W to 19N66W and it is interacting with a nearby upper level trough to produce a large area of scattered moderate to isolated strong convection from 24N to 30N and between 44W to 60W. Satellite-derived wind data indicate that the strongest storms are producing fresh to strong winds. A few showers are noted near the southern portion of the trough axis. Another surface trough extends from 14N47W to 09N51W and it is also under the favorable upper level dynamics provided by the previously mentioned upper level trough. A large area of scattered showers and isolated thunderstorms is noted from 11N to 20N and between 42W and 52W. The rest of the tropical Atlantic enjoys fairly tranquil weather conditions. Recent scatterometer satellite data show fresh to locally strong trades from 09N to 19N and between 32W to 59W. Fresh to locally strong NE winds are noted off the coast of Western Sahara from 18N to 25N and E of 25W. Fresh trades are occurring from the NE coast of Cuba to 26N and between 72W and 78W, including the E and central Bahamas. Moderate to locally fresh winds are found elsewhere in the tropical Atlantic. Seas of 7-10 ft are present S of 20N and between 30W and the Lesser Antilles. Seas of 4-7 ft are noted W of 60W and 5-8 ft prevail elsewhere. The Cumbre Vieja volcano, that is on the island of La Palma in the Canary Islands, has been erupting since 19 September at 1410 UTC. Marine and aviation interests should monitor this on-going situation, by reading the Volcanic Ash Advisory, that is issued by Meteo-France, at http://vaac.meteo.fr/volcanoes/la-palma/. For the forecast, the aforementioned low pressure off South Carolina will drift NE and persist off the coasts of the Carolinas through Sun. Some non-tropical development will be possible over the weekend due to the system interacting with a frontal boundary. Regardless of development, this system could bring heavy rain to the offshore zones N of the Bahamas. Moderate to fresh E winds S of 25N will continue through Fri and then resume Sun into Mon night as high pres builds into the region and both a tropical wave and low level disturbance move across the E Caribbean. $$ DELGADO