000 AXNT20 KNHC 162137 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sun Oct 17 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 2130 UTC. ...SPECIAL FEATURES... Atlantic Gale Warning: A cold front extends from a 1000 mb low near the Azores Islands to near 26N50W. A tight pressure gradient between the front and a surface ridge to the east is supporting minimal gale force winds within 120 nm east of the front from 29N to 31N. A recent Jason-3 radar altimeter satellite pass indicated seas reaching in excess of 16 ft in the area of gale force winds. The low pressure area will continue to shift further NE away from the area, with the gales moving north of the area by tonight. Gulf of Mexico Gale Warning: A cold front extends from near Apalachicola, Florida to near Poza Rica, Mexico. NW to N winds are funneling along the coast of Mexico near Tampico and reaching gale force this afternoon. Scatterometer satellite passes indicated fresh to strong N to NE winds elsewhere north of the front, and off Veracruz, Mexico. Seas behind the front may be 8 to 10 ft over the northwest Gulf. Increasing winds and building seas will spread southward, extending off the coast of Veracruz, Mexico on Sun. Seas will peak near 13 ft off Veracruz, Mexico by Sun afternoon. 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 on both warnings. ...TROPICAL WAVES... The axis of a tropical wave is near 37W south of 18N, moving W at 10 to 15 kt. An earlier scatterometer data depicted a decent curvature with this wave. Scattered moderate convection is from 02N to 10N between 32W and 39W. The axis of a tropical wave is near 50W south of 19N, moving W at 10 to 15 kt. No significant convection is related to this wave at this time. The axis of a tropical wave is over the central Caribbean near 70W/71W south of 20N, moving W at 10 to 15 kt. Scattered moderate to strong convection is observed over northwest Venezuela. The axis of a tropical wave is near 84W south of 18N, moving W at 10 to 15 kt. Scattered moderate convection is noted over eastern Nicaragua. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Senegal near 14N17W to 07N23W. The ITCZ continues from 07N23W to 04N30W to 04N34W. It resumes from 04N39W to 04N48W. Aside from convection mentioned in the Tropical Waves section, scattered moderate convection is noted from 01N to 07N between 22W and 32W. GULF OF MEXICO... Refer to the Special Features for information on the Gale Warning in effect for the SW Gulf of Mexico. Aside front the cold front described above, a pre-frontal trough extends from 30N83W to 24N90W. Scattered showers and a few thunderstorms are noted south of 24N and west of 90W. A weak pressure pattern continues across the remainder of the basin, supporting light to gentle breezes and slight seas. For the forecast, the cold front will continue moving SE across the basin, then stall across the south-central Gulf through Tue and dissipates. Winds and seas will diminish across the basin Mon into Tue, but increase slightly over the eastern Gulf into mid week as high pressure builds north of the region. CARIBBEAN SEA... Please refer to the section above for details on the tropical waves moving across the basin. An upper trough extends from an upper low over the Straits of Florida through the Gulf of Honduras. Upper level divergent flow southeast of this trough is supporting clusters of showers and thunderstorms over much of the south-central and southwest Caribbean, from 11N to 15N west of 75W. Mostly gentle to moderate trade winds persist across the basin with 2 to 4 ft seas. For the forecast, a cold front will enter the northwest Atlantic over the weekend and move southeastward. High pressure building in the wake of the front will bring a return to moderate trade winds to the Caribbean Mon night through Tue and then moderate to fresh winds late Wed. ATLANTIC OCEAN... W Atlc Please refer to the Special Features section above for details on the Gale Warning and tropical waves currently across the basin. A 1011 mb surface low is centered near 29N69W. A surface trough extends from the low to 26N71W. No significant convection is related to these features at this time. This pattern is maintaining light to gentle breezes and 2 to 4 ft seas in open waters west to 65W. Farther east, gales are active ahead of the cold front as described in the Special Features section. Seas in excess of 8 ft are evident north of 22N and west of the front to 50W. Moderate NE to E winds and 4 to 6 ft seas are noted elsewhere. The Cumbre Vieja volcano, on the island of La Palma in the Canary Islands, has been erupting since 19 September 2021. Low ash concentrations moving NW. 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 west of 65W, a cold front will move off the southeast U.S. coast tonight and continue southeastward across all of Florida by Sun night, reaching from Bermuda to the Straits of Florida by Mon morning. Expect fresh to strong N to NE winds behind the front through Mon morning. High pressure will shift ESE across the western Atlantic along 31N-32N Tue through Wed. $$ Christensen