000 AXNT20 KNHC 111804 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sun Apr 11 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 1200 UTC surface analysis and satellite imagery through 1650 UTC. ...SPECIAL FEATURES... Windward Islands Ashfall Advisory: La Soufriere volcano on the island of Saint Vincent near 13.3N 61.2W is undergoing frequent eruptions. Satellite imagery shows the volcanic ash plume spreading well to the east and northeast of St. Vincent, roughly in an area from 10N-18N between 40W-62W, which includes Barbados. Violent volcanic eruptions may occur suddenly without warning. Volcanic ash may be reaching the ocean surface east northeast of St. Vincent. Mariners should exercise caution, and report volcanic ash or floating debris to the National Weather Service by calling 305-229-4424. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends southward from the coast of Guinea-Bissau near 12N16W to 04N22W, where it transitions to the ITCZ to 01N30W to 02S43W. Scattered moderate convection is within 240 nm south of the ITCZ between 21W-26W. GULF OF MEXICO... A cold front is slowly moving east across the NW Gulf. As of 15 UTC the front stretches from the western edge of the Florida Panhandle to northeast Mexico near 25N97W, and the latest scatterometer pass revealed moderate N-NE winds behind the front. Ahead of the boundary, a cluster of thunderstorms continues to move across the NE Gulf and Northern Florida north of 27N and east of 88W. With a rather potent upper-level trough located over the eastern Gulf and ample available moisture in place at the low- levels from persistent fresh southerly winds along with daytime heating, expect additional clusters of strong to severe thunderstorms to develop over the NE Gulf and over central Florida. The main hazards associated with these storms are likely to be wind gusts of 35-45 kt and frequent lightning. The storms will propagate east-southeastward during the day. Elsewhere in the Gulf, a 1006 mb low is along a surface trough is located near 22N94W in the southwest Gulf. Gentle to moderate winds are in the southern Gulf around the low. Seas across the basin are 3-5 ft. The cold front over the northern Gulf will move eastward, reaching from north Florida to the east-central Gulf by late tonight. It will weaken further to a trough as it reaches the southeastern Gulf Mon and dissipates late Mon. An upper- level trough will help generate scattered showers and thunderstorms over most of the eastern Gulf waters today. Some of this activity may contain frequent lightning and strong gusty winds. CARIBBEAN SEA... See the Special Features section above for details on an Ashfall Advisory issued for ongoing volcanic eruptions on St. Vincent. The latest surface analysis depicts a rather weak pressure gradient across the basin. ASCAT data shows fresh trades over most of the basin, while fresh to strong east-southeast winds in the Gulf of Honduras as well as the Yucatan Channel. Mainly fair weather conditions are in place across the basin. Wave heights are in the 3-6 ft range, except for slightly higher wave heights of 5-7 ft in the central Caribbean area and within the Gulf of Honduras. For the forecast, fresh southeast winds will continue over the northwestern Caribbean through this afternoon, while fresh to strong east to southeast winds continue in the Gulf of Honduras. Winds will pulse to strong speeds over a small area near the coast of Colombia during the afternoons and at night through Wed. Elsewhere, generally moderate to fresh east winds will change little through Thu night. ATLANTIC OCEAN... See the Special Features section above for details on an Ashfall Advisory issued for ongoing volcanic eruptions on St. Vincent. The latest scatterometer data shows fresh to strong southerly winds west of 73W. Numerous showers and thunderstorms are moving E-SE across the Florida Peninsula. Storms are currently offshore northern Florida north of 26N and west of 76W. Storms will bring frequent lightning and strong gusty winds to the coastal waters between Florida and the Bahamas later today and tonight. For the forecast, fresh to strong southerly winds east of Florida will shift eastward through Mon ahead of a cold front that will move off the southeastern U.S. coast tonight. The front will reach from near 31N75W to east-central Florida early Mon, from near 31N70W to the central Bahamas and to east-central Cuba Mon evening and the southeast waters by late Tue. The front will move east of the forecast waters on Wed as weak high pressure builds in behind it. Another cold front is expected to cross the northwest and north- central waters beginning Tue. Fresh to strong southwest winds are expected to precede this front. Scattered to numerous showers and thunderstorms, some strong to severe, are expected to push off the Florida coast today. Farther east, a large area of fresh to strong west winds associated with a low pressure system north of our discussion area continues to affect waters north of 26N between 27W-51W. Seas are 11-17 ft in this area. Northerly swell from this system, with seas in excess of 8 ft, is affecting most of the central Atlantic north of 21N between 26W-63W. Fast-moving small cells of showers and thunderstorms are seen rotating cyclonically in the southern semicircle of this low. This activity is brushing the waters north of 29N between 39W- 48W. Cold air instability aloft is helping to sustain this activity. South of the low, weak surface trough is analyzed from 30N30W to 15N62W. Upper-level diffluence to the east of the northeastern portion of the surface trough is aiding an area of scattered moderate convection east of the trough from about 24N to 32N between 23W-31W. High pressure ridging and gentle anticyclonic flow dominates the waters east of the trough. $$ Mora