000 AXNT20 KNHC 111757 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Thu Nov 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 1200 UTC surface analysis and satellite imagery through 1630 UTC. ...SPECIAL FEATURES... Showers and thunderstorms associated with a storm-force non- tropical area of low pressure located more than 1000 miles ENE of Bermuda have changed little in organization since last night. Although there is still a small chance the system could become a short-lived subtropical storm today, the system is quickly moving over cooler waters and the likelihood of subtropical development has decreased. Therefore, the chance of development has decreased to low. Additional information on this system, including hurricane- force wind warnings, can be found in High Seas forecasts issued by the National Weather Service at website - ocean.weather.gov/shtml/NFDHSFAT1.php ...MONSOON TROUGH/ITCZ... A monsoon trough exits the African coast near the Guinea-Sierra Leone border at 09N13W through a 1011 mb low near 07N16W to 07N21W, then continues as an ITCZ to 08N40W to 07N56W; just N of Suriname. Numerous moderate to isolated strong convection is noted near the low and part of the ITCZ from 02N to 10N between the African coast and 26W. Scattered moderate convection is seen farther W near the ITCZ from 06N to 09N between 27W and 35W, and from 05N to 09N between 48W and the Suriname-French Guiana border. The E Pacific monsoon trough is causing scattered showers near Costa Rica, Panama and nearby Caribbean waters. ...GULF OF MEXICO... An outflow boundary is triggering scattered showers and thunderstorms over the NW corner of the Gulf, S of Galveston, Texas. Fresh with locally strong winds with seas up to 6 ft are expected near this boundary. Otherwise, a broad surface ridge is supporting light to gentle ESE to SSW winds and seas at 2 to 4 ft across much of the Gulf. On the forecast, a cold front will move into the N Gulf coastal waters tonight, move southward across the Gulf Fri then stall and dissipate across the Yucatan Channel Sat. A reinforcing front will follow closely behind the first front, entering the N Gulf Fri night, then move southeastward across the Gulf through Sun. Looking ahead, high pressure building across the N Gulf on Sun will strengthen into Mon, supporting fresh winds over the SE and S central Gulf. ...CARIBBEAN SEA... A surface trough is coupling with divergent winds aloft to trigger scattered showers and thunderstorms across the W basin, including W Cuba. The western end of a shear line is producing similar conditions over the N coast of central Cuba. Refer to the Monsoon Trough/ITCZ section for additional weather in the basin. Recent satellite scatterometer and altimetery data indicate moderate to fresh easterly trades and seas of 5 to 6 ft over the S central and NW basin. NE to E gentle to moderate trades with seas at 2 to 4 ft prevail for the rest of the basin. For the forecast, the shear line over N Cuba will be dissipating through tonight. Afterward, a cold front will stall over the Yucatan Channel Sat, then dissipate. A slight stronger front will move into the NW Gulf Sun then stall from E Cuba to the Gulf of Honduras. Looking ahead, this second front will shift eastward into the Windward Passage through Mon as reinforcing high pressure builds N of the area behind a third front moving through the W Atlantic. This pattern will support fresh NE winds across parts of the NW Caribbean Mon and Mon night. ...ATLANTIC OCEAN... A weakening cold front curves southwestward from the N central Atlantic across 31N44W to near 24N58W, then continues westward as a shear line across the SE Bahamas to the N coast of central Cuba. Scattered showers and isolated thunderstorms are occurring up to 80 nm on both sides of this boundary between 31N44W and 22N72W, and also from the N coast of Cuba northward to the NW Bahamas. An upper-level trough near 24N20W is generating scattered showers along the Guinea-Bissau/Senegal/Mauritania coast and adjacent waters. Refer to the Monsoon Trough/ITCZ section of additional convection in the basin. N to ENE gentle to moderate with locally fresh winds and seas of 7 to 10 ft are present near and N of the cold front/shear line, between 46W and the Florida coast/Bahamas. Moderate to fresh NE trades and seas at 5 to 7 ft are found near the Canary Islands from 23N to 28N between the NW African coast and 21W. A 1018 mb high over the central Atlantic is promoting light to gentle winds and seas of 4 to 5 ft N of 20N between 21W and 46W. Gentle to moderate NNE to ENE trades with seas at 4 to 5 ft are present from 08N to 20N between the African coast and Lesser Antilles. Gentle to moderate with locally fresh E to SE trades and seas of 4 to 6 ft prevail for the remainder of the basin. For the forecast west of 65W, high pressure between Bermuda and NE Florida will shift east today ahead of a cold front that will move off the NE Florida coast by early Fri. The front will stall and weaken from roughly 31N72W to central Cuba by early Sat. Afterward, a second front will move off the NE Florida coast later on Sat, then merge with the first front before stalling from roughly Bermuda to central Cuba Sun. Looking ahead, a third, stronger front will move off the NE Florida coast late Sun night, eventually overtaking the aforementioned stalled front, and then reach from 27N65W to the Windward Passage by late Mon. 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 latest Volcanic Ash Advisory issued by Meteo-France at website http://vaac.meteo.fr/volcanoes/la-palma/. $$ Chan