000 AXNT20 KNHC 150558 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 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 0000 UTC surface analysis and satellite imagery through 0540 UTC. ...SPECIAL FEATURES... Windward Islands Ashfall Advisory: An Ashfall Advisory has been issued, for La Soufriere Volcano, that is on the island of St. Vincent, near 13.3N 61.2W. The volcano currently is in a state of unrest. It is possible that the volcano may erupt with little notice. It is possible that ash that was released earlier may be reaching the surface of the ocean, and low level visibility may be reduced. Mariners who are transiting the waters under the emitted ash advisory should exercise caution. Mariners who encounter volcanic ash or floating volcanic debris, are urged to report the observation to the National Hurricane Center, by calling 305-229-4424. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Guinea-Bissau near 12N16W, to 05N20W. The ITCZ continues from 05N20W, 02N23W, to 01N30W, to the Equator along 39W. Precipitation: scattered to numerous moderate to strong is from 120 nm to 180 nm to the north of the ITCZ between 27W and 32W, and from 02N to 04N between 48W and 51W. Broken to overcast multilayered clouds, and isolated to widely scattered moderate, are from 05N to 16N between 44W and 60W. Isolated moderate to locally strong is elsewhere, from 10N southward from 50W eastward. GULF OF MEXICO... A stationary front is in the coastal plains, from Louisiana to Texas. Precipitation: scattered to numerous moderate-to-strong is in parts of SE Louisiana, the coastal sections of Mississippi, and SW Alabama. Warming cloud top temperatures, and lingering but dissipating precipitation, cover the waters from 27N northward. A cold front will reach the northern Gulf of Mexico on Thursday, then stall and weaken on Friday. A stronger cold front will move into the NW Gulf of Mexico on Saturday, with strong northerly winds and building seas expected across the western Gulf of Mexico this weekend. The front will stall from central Florida to the Bay of Campeche on Monday morning. CARIBBEAN SEA... The GFS model for 250 mb shows: broad anticyclonic wind flow in the Caribbean Sea. The GFS model for 500 mb shows: a trough along 64W; and anticyclonic wind flow from 16N northward from Jamaica westward. The GFS model for 700 mb shows: cyclonic wind flow from 15N southward from 70W westward; a ridge from 14N60W to 16N75W; anticyclonic wind flow from 15N northward from 75W westward. A surface trough is along 11N73W in northern Colombia, to the Colombia/Panama border, beyond 07N80W, into the eastern Pacific Ocean. Precipitation: widely scattered moderate to isolated strong is in Colombia to the southeast of the surface trough. Scattered to numerous strong is in Costa Rica and southern Nicaragua from 09N to 12N. Numerous strong is in NW Venezuela, between Lake Maracaibo and the border with Colombia. Widely scattered to scattered moderate and isolated strong is from 12N southward from 78W westward. Broken to overcast low level clouds, and isolated moderate rainshowers, cover the rest of the Caribbean Sea. The clouds and isolated moderate precipitation are moving with the surface-to-low level wind flow. An Ashfall Advisory is in effect for La Soufriere Volcano on the island of St. Vincent near 13.3N 61.2W. Mariners who are transiting the nearby waters should exercise caution, and are encouraged to report volcanic ash to the National Hurricane Center, by calling 305-229-4424. Moderate to fresh trade winds will prevail in the Caribbean Sea through Saturday. Fresh to strong SE winds are expected in the NW Caribbean Sea this weekend. ATLANTIC OCEAN... The first cold front passes through 32N52W, to 25N60W, to 21N70W, to the south of the SE Bahamas, to the coast of Cuba near 21N75W. Precipitation: isolated moderate rainshowers are within 120 nm to the east of the first cold front from 23N northward. A 1020 mb high pressure center is near 30N76W. Surface anticyclonic wind flow covers the Atlantic Ocean to the west and northwest of the first cold front. A second cold front passes through 32N47W to 27N50W, 20N58W, and to 18N61W. Precipitation: widely scattered moderate to isolated strong is within 540 nm to the east of the cold front from 30N northward, and from 20N to 30N between 40W and the cold front from 20N to 30N. Isolated moderate is between 40W and the cold front from 17N to 20N. A 1022 mb high pressure center is near 31N29W. Surface anticyclonic wind flow covers the Atlantic Ocean from 10N northward from the 32N47W 18N61W cold front eastward. The current weakening cold front, that is to the northeast of the Leeward Islands, will move to the east of the area overnight. The trailing cold front, from 22N65W to just to the north of the Windward Passage, will stall and weaken through Thursday. Another cold front will move to the east of northern Florida into the northern waters by early Friday, then stall to the north of the Bahamas, from this weekend into early next week. $$ mt/DM