000 AXNT20 KNHC 142316 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Thu Apr 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 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... Windward Islands Ashfall Advisory: An Ashfall Advisory remains in effect for La Soufriere Volcano that is on the island of St. Vincent near 13.3N 61.2W. A new explosive eruption has occurred this afternoon, and the ash plume is forecast to reach Barbados this evening and tonight. Ash may be reaching the surface of the ocean, and low-level visibility may be reduced. Mariners who are transiting the waters between Saint Vincent and Barbados should exercise caution. If you encounter volcanic ash or volcanic debris, please report the observation to the National Hurricane Center, at 305-229-4424. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic ocean through the coast of west Africa near 12N16W and continues SW to 07N22W. The ITCZ extends from 07N22W to 02N35W to 04N45W to the coast of Brazil near 03N51W. A cluster of moderate to isolated strong convection is noted from 03N-05N between 22W-25W. Scattered moderate convection can be found from 01N-03N between 44W-48W. GULF OF MEXICO... High pressure of 1021 mb located E of NE Florida extends a ridge across Florida into the Gulf of Mexico producing gentle to moderate winds across the western half of the Gulf, and moderate to fresh E-SE winds across the eastern half of the Gulf region. Convection has flared-up across the north-central Gulf ahead of a frontal boundary. The ridge will remain in place through tonight. A cold front will reach the northern Gulf Thu, then stall and weaken on Fri. A stronger cold front will move into the Northwest Gulf on Sat, with strong northerly winds and building seas expected across the western Gulf this weekend. The front will stall from near Tampa Bay, Florida to the Bay of Campeche early next week. CARIBBEAN SEA... An Ashfall Advisory remains in effect for La Soufriere Volcano on St. Vincent. Please refer to the Special Features section above for more details. A ridge dominates Cuba and the NW Caribbean while a weak pressure gradient noted over the eastern Caribbean thanks to the presence of a frontal boundary near Puerto Rico. The most recent scatterometer pass showed moderate to fresh NE winds across the Windward Passage and downwind to just E of Jamaica. Similar wind speeds are noted near the coast of Colombia, and in the Gulf of Honduras. For the forecast, moderate to fresh trade winds will prevail across the Caribbean through Sat, except pulsing locally to fresh to strong through the Windward Passage, south of Hispaniola, and north of Colombia through early Thu, then in the south-central Caribbean this weekend into early next week. SE winds will pulse to fresh to strong in the NW Caribbean starting early Fri through the weekend as a cold front moves across the Gulf of Mexico. ATLANTIC OCEAN... An Ashfall Advisory remains in effect for La Soufriere Volcano on the island of St. Vincent. Please refer to the Special Features section above for more details. A pair of cold fronts are moving across the western-central Atlantic waters. The primary cold front extends from 31N48W to the easternmost tip of Dominican Republic. The second cold front enters the forecast waters near 31N56W and continues SW to near the Turks and Caicos Islands. Scattered moderate convection is noted ahead of the first front, particularly N of 21N E of front to 45W. The primary cold front will move eastward on Thu while weakening. The secondary front will dissipate over the next 12-24 hours. Moisture associated with the primary front will affect the Leeward Islands on Thu and Fri. Another cold front will move east of northern Florida into the northern waters by early Fri, then stall north of the Bahamas this weekend into early next week. The remainder of the Atlantic forecast area is under the influence of 1023 mb high pressure located near 29N31W. The pressure gradient between this system and lower pressure over west Africa will result in fresh trade winds across the Cabo Verde Islands, and between these islands and the coast of W Africa Thu and Fri. By Fri night into Sat, the trade wind flow will increase some between 35W and 50W. $$ GR