495 AXNT20 KNHC 200507 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Sat Nov 20 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 0455 UTC. ...SPECIAL FEATURES... Gulf of Mexico Gale Warning: A stationary front extends from near St. Petersburg, Florida to inland Mexico near Coatzacoalcos as of 0300 UTC. NW-N gale-force winds are confined to the far SW Gulf S of 21N and W of 95W, with seas of 8-12 ft. A recent altimeter satellite pass indicate seas up to 12 ft off Veracruz, Mexico. Winds will slacken and seas will subside today as the pressure gradient decreases and the frontal boundary weakens. Please see the latest NWS High Seas Forecast issued by the National Hurricane Center at website www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more information. ...MONSOON TROUGH/ITCZ... The monsoon trough remains over Africa. The ITCZ begins near 06N16W to 07N30W. A surface trough extends from 16N30W to 03N38W, interrupting the ITCZ. The ITCZ then resumes near 07N39W to 05N50W. Scattered moderate to isolated strong convection is observed from 02N to 13N and E of 40W. GULF OF MEXICO... Please see the Special Features section above for details on a Gale Warning that is currently in effect for a section of the SW Gulf. The aforementioned stationary front extends from central Florida to near Coatzacoalcos, Mexico in the SW Gulf. Abundant moisture, low-level wind convergence and divergence aloft result in a large area of cloudiness and widespread showers, mainly S of 25N and W of 87W. Recent scatterometer satellite pass show fresh to strong NE winds covering most of the basin. The exception being the NW Gulf where winds have decreased to fresh to moderate. Seas of 6-9 ft are occurring in the SW Gulf outside of the gale warning area, while 3-6 ft prevail elsewhere. For the forecast, the previously-mentioned front will drift south while dissipating this weekend. Strong northerly winds and rough seas follow the front. Winds to minimal gale force off Veracruz are ongoing and will gradually diminish tonight. Another cold front will enter the northwest Gulf early Mon, and move south of the basin late Mon night. Fresh to strong winds are expected behind the front. High pressure will build across the Gulf region in the wake of the front. CARIBBEAN SEA... Most of the Caribbean Sea enjoys fairly tranquil weather conditions. The exception is found within 60 nm of the coast of Nicaragua where abundant moisture and low-level convergence are inducing a few showers. The pressure gradient across the basin has diminished as the strong ridge north of the Caribbean has tracked eastward and further away from the region. Fresh to locally strong trades are occurring in the central Caribbean, with the strongest winds affecting the waters offshore of NW Colombia. Moderate or weaker winds prevail elsewhere. Seas of 3-6 ft are found in the SW, central and E Caribbean, while 1-3 ft seas are prevalent in the rest of the basin. For the forecast, high pressure north of the area will shift east, ahead of a cold front moving off NE Florida. Winds and seas will further diminish early next week, ahead of a stronger cold front moving through the Gulf of Mexico Mon. The front will reach the Yucatan Channel by late Mon night and extend from eastern Cuba to the Gulf of Honduras by late Tue. Fresh to locally strong winds and building seas are expected in the wake of the front. ATLANTIC OCEAN... A cold front extends from the Canadian Atlantic provinces to central Florida, entering the tropical Atlantic near 31N74W. A pre-frontal trough extends from 23N to 29N along 78W, crossing the NW Bahamas. Scattered moderate to isolated strong convection is noted to the east of the front and trough axis, with the strongest convection occurring just east of the NW Bahamas. A recent scatterometer satellite pass show fresh to strong winds N of 24N and W of 72W. Seas W of 60W are 6-10 ft, with the highest seas occurring to the north of the frontal boundary. Farther east, a shear line extends from 31N34W to 23N51W and only a few isolated showers are seen near its axis, mainly W of 49W. Satellite-derived wind data show fresh to locally strong N-NE winds behind the shear line, extending north to 31N. Nearby, a 1011 mb low pressure system is analyzed near 27N32W and surface troughs extend from the low, southwestward to 18N39W and eastward to 26N25W. A large area of showers and isolated thunderstorms is located to the east of the low pressure, mainly N of 27N and between the low pressure and 21W. Scatterometer satellite data depict a small area of fresh SE-S winds east of the low pressure. The rest of the basin enjoys fairly tranquil weather conditions and moderate or weaker winds. Seas of 6-10 ft are found N of 20N and between 25W and 60W, with the highest seas occurring over the open Atlantic near 30N40W. Elsewhere in the basin, seas of 3-6 ft are prevalent. Northerly swell, generated by a strong low pressure system located north of the area, will reach the forecast waters late on Sat, building seas to 10-14 ft roughly north of about 28N and between 25W-40W by Sun morning. The Cumbre Vieja volcano, on the island of La Palma in the Canary Islands, has been active for two months(since 19 September 2021). An ash emission is ongoing. Medium ash concentration is noted in the vicinity of the volcano, low elsewhere. 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, cold front extending from 31N75W to near Cape Canaveral, Florida will remain across the northern forecast waters this weekend, before lifting north ahead of a stronger cold front that will move off the northeast Florida coast on Mon. The second front will reach from near Bermuda to eastern Cuba by late Tue. Fresh to strong northerly winds and building seas are expected behind the fronts. $$ DELGADO