000 AXNT20 KNHC 150420 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Fri Oct 15 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. ...SPECIAL FEATURES... Atlantic Gale Warning: A broad 1004 mb low pressure is located between the Leeward Islands and Bermuda near 26N63W with a warm front extending to the east and a surface trough extending SW to the SE Bahamas. A large area of showers and isolated thunderstorms extends to the east and south of the low pressure, mainly from 20N to 28N and between 50W and 64W. Recent scatterometer satellite data indicate that strong to near-gale force winds are already occurring within 150 nm of the south of the center. The low is forecast to deepen as it moves east- northeast and accelerates to the northeast by Fri. Gale force winds are expected to develop south of the low by Fri 1200 UTC, from 25N-27N between 54W-57W. The area of gale force winds will move east-northeastward, moving N of the area by 1800 UTC on Saturday. Seas up to 13 ft are expected within the area of gales. Please read the latest High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. ...TROPICAL WAVES... An Atlantic tropical wave has its axis along 25W, south of 18N and it is moving W at around 15 kt. Scattered moderate convection is noted from 07N and 11N and 23W and 27W. A stable airmass N of 11N suppresses the development of showers and thunderstorms. Another Atlantic tropical wave has its axis along 40W, south of 18N, and it is moving W at around 15 kt. Scattered moderate to isolated strong convection is noted from 05N and 11N and 37W and 43W. A stable airmass N of 11N suppresses the development of showers and thunderstorms. A third Atlantic tropical wave has its axis along 61W, south of 17N, extending across the Lesser Antilles into E Venezuela and N Brazil, and it is moving W at around 15 kt. No deep convection is observed near the wave axis. However, it is likely enhancing the formation of showers over E Venezuela. A Caribbean tropical wave has its axis along 74W, south of 19N, extending from Haiti to N Colombia, and it is moving W at 10-15 kt. No deep convection is present near the wave axis. However, it is likely enhancing the formation of showers and isolated thunderstorms over N Colombia. Another Caribbean tropical wave has its axis along 86W, south of 20N, extending across Honduras and W Nicaragua into the E Pacific and it is moving W at 10-15 kt. Scattered moderate convection is seen over Central America near the wave axis. ...MONSOON TROUGH/ITCZ... A monsoon trough extends from the coast of Guinea-Bissau near 11N16W to 05N20W. The ITCZ extends from 05N20W to 05N25W, then continues W of a tropical wave from 05N26W to 05N39W. Another segment then continues from 05N41W to the coast of French Guiana near 06N54W. Scattered moderate to isolated strong convection is noted within 300 nm of the ITCZ between 43W and 51W and also between 37W to 27W. A few showers are observed near the monsoon trough E of 21W. GULF OF MEXICO... The Gulf of Mexico remains in the southwestern periphery of a weak ridge positioned over the eastern United States. A weak pressure gradient results in moderate or weaker anticyclonic winds to prevail across the basin. A weak surface trough located in the NE Gulf along 87W from 26N to 29N is producing a few shallow showers. The rest of the Gulf enjoys fairly tranquil weather conditions. Seas of 3-5 ft are occurring W of 94W, while 1-3 ft seas are present elsewhere. For the forecast, the aforementioned high pres extending from the eastern U.S. southwestward to the N central Gulf will influence the Gulf waters during the next few days. A cold front will enter the NW Gulf Fri night with fresh to strong northerly winds following it. The front will reach south central Florida to western Bay of Campeche Sun morning with moderate to fresh N to NE winds across most of the Gulf. Gale- force N winds are possible across the Mexican waters Sat night and are expected to develop off of Veracruz Sun morning through afternoon. CARIBBEAN SEA... Refer to the section above for details on the tropical waves moving across the basin. A deep upper level trough continues off the SE United States, protruding into the NW Caribbean and reaching Central America, is interacting with tropical moisture to produce a large area of widespread shallow showers extending from Nicaragua to Hispaniola. A surface trough extends from near Puerto Rico to near the low pressure well north of the islands and a few showers and isolated thunderstorms are observed near the trough axis, affecting parts of Puerto Rico and the Virgin Islands. A weak pressure gradient across the Caribbean Sea results in moderate or weaker trades in the basin. Seas of 3-5 ft are occurring E of 75W and 1-3 ft seas are present elsewhere. For the forecast, an upper level trough extending from the Bahamas to the NW Caribbean will support active weather across the central Caribbean and extreme NE Caribbean through Fri. Low pres NE of the Bahamas will shift E-NE through Fri, then accelerate NE into the weekend. This will weaken the pressure gradient across the Caribbean basin leading to tranquil marine conditions. ATLANTIC OCEAN... Please refer to the section above for details on the tropical waves moving across the basin and the Gale Warning currently in effect. Aside from the low pressure system mentioned in the Special Features section, the other feature of interest is a cold front that enters the tropical Atlantic near 31N32W and becomes a stationary front that continues to a 1009 mb low pressure near 29N48W. The stationary front then exits the tropical Atlantic near 31N61W. Scattered moderate convection is noted within 200 nm on both sides of the frontal boundary. The strongest convection is found N of 29N and between 28W and 33W. Scatterometer satellite data indicate that fresh southerly winds are occurring with the strongest convection. A surface trough NE of the NW Bahamas from 31N68W to 28N76W is producing a few showers near its axis. The rest of the tropical Atlantic is dominated by a broad 1022 mb high pressure located in the far NE Atlantic that stretches to the Lesser Antilles. Recent scatterometer satellite data depict fresh to strong trades from 08N to 15N and between 30W and 44W. Fresh N winds are also occurring E of 22W and from 18N to 24N, with the strongest winds affecting the waters off Western Sahara and NW Mauritania. Seas of 7-10 ft are found N of 24N and 27W and 40W. Seas of 5-8 ft prevail to the W of 55W and 6-9 ft seas are prevalent S of 25N and E of 55W. Seas of 4-7 ft are noted elsewhere in the basin. The Cumbre Vieja volcano, on the island of La Palma in the Canary Islands, has been erupting since 19 September 2021. Significant volcanic ash is possible near the volcano. 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 W of 55W, the aforementioned low pres 1004 mb near 26N63W will move E-NE tonight then accelerate NE and exit the area on Fri. This system will produce active weather that will impact the regional waters through early Fri. A cold front will move southeastward across Florida by the end of the weekend, bringing fresh northerly winds off the Florida coast. $$ DELGADO