000 AXNT20 KNHC 142246 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 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 1800 UTC surface analysis and satellite imagery through 2230 UTC. ...SPECIAL FEATURES... Atlantic Gale Warning: A complex low pres system is developing across the western Atlantic. A 1006 mb low pressure is located NE of the Bahamas near 25N68W with a trough extending from it to a 1003 mb low near 26N63W. Scattered to numerous moderate convection is from 20N-30N between 50W-65W. The lows are expected to merge and deepen as it moves east and accelerates to the northeast by Fri. Gale force winds are expected to develop south of the new merged 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... A tropical wave has been introduced to the analysis. The wave's axis extends along 23W from 02N-18N, moving W at 10 to 15 kt. Scattered showers are noted S of 14N between 20W-24W. An Atlantic tropical wave has its axis along 39W S of 17N, moving W at 15-20 kt. The convection in the vicinity of the wave is mostly related to the proximity of the ITCZ, which extends along 07N. Another Atlantic tropical wave has its axis along 59W S of 17N, moving W at 10 to 15 kt. Scattered moderate convection is noted along the wave axis from 10N-13N. A central Caribbean tropical wave axis extends along 73W from 05N-19N, moving W at 10-15 kt. Scattered moderate convection is noted from 15N-20N between 70W-73W. A western Caribbean tropical wave has its axis along along 85W and N of 04N, moving W at 10 to 15 kt. Scattered showers are noted from 05N to 12N between 87W and 87W. ...MONSOON TROUGH/ITCZ... A monsoon trough extends from the border of Guinea and Guinea-Bissau near 11N15W to 08N23W. The ITCZ extends from 08N25W to 08N37W, then continues W of a tropical wave from 07N41W to 10N55W. Aside from the convection mentioned in the tropical waves section above, scattered moderate convection is noted from 06N-10N between 25W-52W. GULF OF MEXICO... Weak surface ridging covers most of the Gulf of Mexico. The latest ASCAT data depicts gentle to moderate E winds covering the area E of 93W, where seas are 2 to 4 ft. Relatively dry conditions cover this area. Fresh SE to SSE winds are over the far western Gulf of Mexico, W of 94W, confirmed by the latest ASCAT data. Seas are 4 to 6 ft in this area. Strong thunderstorms are noted along the coast of Texas between Freeport and Corpus Christi. These storms are the result of remnant moisture from East Pacific post-tropical Pamela, which dissipated, and then combined with a weakening frontal boundary/trough. These thunderstorms are expected to dissipate by the evening hours. The high pres will influence the Gulf waters during the next few days. A cold front 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. An upper-level low centered near the central and northwest Bahamas extends an upper-level trough SW to Honduras. Upper- level divergence to the east of the upper-trough axis is enhancing scattered showers and thunderstorms across most of the basin between 60W-77W. The latest ASCAT data shows moderate SE winds in the eastern Caribbean, where seas are 3 to 5 ft. ASCAT shows gentle wind speeds in the western half of the basin, where seas are 1 to 3 ft. The upper level trough will persist from the Bahamas to the NW Caribbean supporting active weather across the central 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 convection related to the Special Features system described above, the only area of scattered showers is noted in the vicinity of a frontal boundary that extends from 31N34W to 27N42W to 1010 mb low near 29N50W to 31N59W. Latest ASCAT pass from early depicted strong to near-gale force SW winds within 180 nm E of the front, mainly north of 28N and east of 37W, where seas are likely 10 to 12 ft. A surface ridge axis extends from 1021 mb high pressure near 39N13W to 1018 mb high near 24N30W to 20N55W. Gentle anticyclonic winds are near the ridge axis. 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 65W, High pressure ridge E of 60W will shift E and weaken through the end of the week. Low pres system near Bahamas will move E-NE tonight then accelerate NE and exit the area on Fri. This system will continue to produce very active weather and 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. $$ ERA