000 AXNT20 KNHC 142239 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Wed Dec 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 2220 UTC. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Sierra Leone near 07N12W to 05N17W. The ITCZ continues from 05N17W to 06N35W to the coastal border of French Guiana and Brazil near 04N51W. Scattered moderate convection is noted from 03N-07N between 20W and 31W. GULF OF MEXICO... High pressure of 1031 mb located over over the southeast U.S. extends a ridge across the entire Gulf of Mexico. A surface trough is analyzed over the western Bay of Campeche. Low clouds with embedded showers are associated with the trough. Moderate to fresh NE winds prevail over the southeast Gulf with gentle to moderate winds elsewhere. Seas are 4-6 ft over the southeast Gulf, including the Yucatan Channel, 1-3 ft over the northeast Gulf, and 3-5 ft elsewhere. For the forecast, high pressure will prevail across the forecast waters through the week. Fresh east winds will spread westward through the Straits of Florida and into the eastern Gulf S of 26N through midweek along with building seas. A cold front is forecast to enter the basin by Sun bringing fresh to strong winds and building seas across the NW Gulf. CARIBBEAN SEA... The pressure gradient from a 1031 mb high pressure centered over the southeast U.S. combined with lower pressure over Colombia is supporting fresh to strong easterly winds over the central Caribbean, including the Windward Passage, south of Hispaniola, and offshore Colombia. Fresh winds prevail across most of the remainder of the basin. Seas are 7 to 8 ft over the south-central Caribbean, and near the Cayman Islands based on a recent altimeter pass. Seas of 5-7 ft prevail elsewhere. Scattered showers and thunderstorms are noted over Nicaragua and regional waters. Similar convection is also seen over the Gulf of Honduras. A diffluent pattern aloft is helping to induce this convective activity. For the forecast, fresh to strong trades will prevail over the central Caribbean through the end of the week. Moderate to fresh trades are expected elsewhere. Strong high pressure will strengthen over the western Atlantic through the forecast period. This will result in fresh to locally strong northeast to east winds in the Windward Passage, Mona Passage, the lee of Cuba, and south of Hispaniola through the week. ATLANTIC OCEAN... The aforementioned high pressure located over the southeast U.S. also dominates the SW N Atlantic producing moderate to fresh NE to E winds S of 24N. Seas are 6-9 ft within this area of winds E of the Bahamas based on altimeter data and buoy observations. Patches of low level clouds with possible showers are E of Florida to about 70W. For the forecast west of 65W, high pressure will prevail across the western Atlantic, supporting moderate to fresh winds over the forecast waters. High pressure will build southward from the middle to end of the week resulting in an increase in winds and seas. This pattern will also increase winds and seas east of 65W through the week. Farther E, a cold front enters the Atlantic forecast waters near 31N48W and extends SW to near 28N56W. Isolated showers are observed ahead of the frontal boundary. A 1026 mb high pressure is situated over the Azores while a surface trough extends from a low pressure located near the Madeira Islands across the Canary Islands. The pressure gradient between the Azores high and lower pressure within the monsoon trough and in the vicinity of the ITCZ is supporting a large area of fresh to locally strong easterly trade winds across the Atlantic from 13N to 24N with 8 to 10 ft seas. 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/. The latest advisory states that eruption has weakened but is still ongoing. Ash plume is drifting south-southeastward. $$ GR