000 AXNT20 KNHC 121702 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Fri Nov 12 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 1655 UTC. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coast of Senegal near 13N17W to 08N23W. The ITCZ then continues from 08N23W to 05N38W to the coast of French Guiana near 05N52W. Scattered moderate to isolated strong convection is observed within 200 nm on both sides of the ITCZ and monsoon trough E of 35W. GULF OF MEXICO... A weak cold front extends from the Big Bend region of Florida near 29N83W to the west-central Gulf of Mexico near 24N93W. A pre- frontal trough extends across Florida and the Florida Keys to the NW Caribbean Sea. Scattered moderate convection is noted near the cold front and trough axis, mainly E of 88W. A recent scatterometer satellite pass show fresh to strong winds in the Florida Straits, likely associated with the strongest storms. Moderate or weaker winds prevail in the rest of the Gulf. Seas of 1-3 ft are prevalent in the basin, with the highest seas occurring in the NW Gulf. For the forecast, the aforementioned cold front will stall over the southeast Gulf tonight. A reinforcing front will enter the basin late tonight followed by strong winds and seas to 8 ft over the northwest and north-central Gulf. The front will sweep through the basin Sat. By Sat night into Sun, high pressure will build into the northern Gulf, and strengthen into Mon. This will support fresh winds late this weekend into early next week across portions of the northwest and southern Gulf, with strong E winds possible over the Straits of Florida. The high pressure will shift east of the region Tue. CARIBBEAN SEA... The main feature of interest in the Caribbean Sea is a surface trough that extends from just W of the Cayman Islands near 19N83W to Florida peninsula. A few showers are present to the E of the trough axis. Satellite-derived wind data indicate that the storm activity is producing fresh to strong winds. The rest of the region is enjoying fairly tranquil weather conditions. A modest pressure gradient due to a strong 1034 mb high pressure over Nova Scotia and lower pressures in NW South America results in fresh to locally strong trades in the south-central Caribbean, with the strongest winds occurring within 90 nm of the coast of NW Colombia. Fresh trades are also noticed in a recent scatterometer satellite pass in the north-central and NE Caribbean. Moderate or weaker trades are found elsewhere. Seas of 4-7 ft are present in the SW, central and E Caribbean Sea, with the highest seas occurring offshore NW Colombia. The remainder of the basin is experiencing 2-4 ft seas. For the forecast, high pressure north of the area is supporting moderate to fresh trade winds across most of the Caribbean. The high will shift east later today, ahead of a cold front that will stall over the Yucatan Channel Sat. A second front will move through the Gulf Sun then stall from eastern Cuba to the Gulf of Honduras by Sun night. Looking ahead, the front will shift eastward into the Windward Passage into Tue as reinforcing high pressure builds north of the area behind a third front moving through the western Atlantic. This pattern will support fresh NE winds across parts of the northwest Caribbean Mon and Tue. ATLANTIC OCEAN... A deep upper level trough continues to dig into the SE United States, bringing a cold front that stretches from New England to the west-central Gulf, crossing central Florida along the way. A pre-frontal surface trough extends from Long Island to 31N77W and crossing southern Florida on its way to the NW Caribbean. The favorable upper level dynamics result in a large area of scattered showers and isolated thunderstorms, mainly W of 73W, affecting the NW and central Bahamas. The latest scatterometer satellite pass depict fresh to locally strong southerly winds ahead of the pre-frontal trough, likely associated with the storm activity. Farther east, a cold front enters the tropical Atlantic near 31N38W and continues SW to 28N45W, becoming a stationary front that then extends to near 22N65W, well north of Puerto Rico. Scattered showers and isolated thunderstorms are noted near the trough axis, mainly E of 44W. A dissipating cold front is barely entering our region, extending from 31N47W to 29N57W. Satellite- derived winds show that fresh to strong winds are occurring behind the frontal boundaries, especially N of 22N and W of 42W, with the strongest winds found behind the dissipating cold front. Elsewhere, a weak surface trough extends from 19N-28N along 36W and it is only producing a few shallow showers near the trough axis. Moderate or weaker winds prevail in the rest of the basin. Seas of 5-8 ft are found W of 60W. N swell produces 8-10 ft seas N of 25N and between 35W and 58W. Seas of 4-7 ft are present in the remainder of the tropical Atlantic. 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 Volcanic Ash Advisory issued by Meteo-France, at http://vaac.meteo.fr/volcanoes/la-palma/. For the forecast W of 65W, the previously-mentioned cold front moving off the NE Florida coast will gradually slow and weaken, and will reach from 31N74W to the Straits of Florida later today. Another cold front will move off the northeast Florida coast late Sat, then merge with first front by early Sun from 31N70W to western Cuba. The merged fronts will stall from near 31N70W through central Cuba by early Mon. Looking ahead, a third front will move off the northeast Florida coast late Sun night, eventually overtaking and merging with the stalled front, and then will stall from 27N65W to the Windward Passage late Mon and Tue. $$ DELGADO