000 AXNT20 KNHC 162356 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sat Apr 17 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 2230 UTC. ...SPECIAL FEATURES... Gulf of Mexico Gale Warning: A cold front is expected to move off the Texas coast and enter the Gulf of Mexico very early Saturday morning. The front will move southward across the basin bringing strong winds and building seas. An area of gale force northerly winds is expected to develop offshore of the Tampico area Saturday night, behind the front. Seas will build to 12 ft in that area, before winds and seas diminish beginning Sunday morning. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at the website: https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details. Eastern Caribbean Ashfall Advisory: An Ashfall Advisory is in effect for La Soufriere Volcano on St. Vincent near 13.3N 61.2W. A new eruption occurred early this morning around 1000 UTC. GOES- 16 Geocolor imagery 2100 UTC near sunset shows that the plume is becoming diffuse over the east central Caribbean. The volcano remains in a very active state, and additional eruptions and ash plumes are possible at any time. Mariners transiting the nearby waters should exercise caution, and are encouraged to report volcanic ash to the National Hurricane Center by calling 305-229- 4424. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic ocean through the coast of Guinea in West Africa near 12N16W and continues southwestward to 06N20W. The ITCZ continues from 06N20W to 01N50W to the coast of Brazil in South America near 01N50W. Scattered moderate convection is seen from 03N-07N between 10W-17W and 00N-04N between 33W and 45W. GULF OF MEXICO... Please see the Special Features section for details on the Gale Warning in effect for the west-central Gulf of Mexico. A stationary front extends from 28N83W near Cedar Key Florida westward to the 29N94W near Houston, TX. Scattered showers and isolated thunderstorms are located north of 28N across the Gulf. South of the front S winds are light to moderate, while north of the front the winds are E moderate to fresh. Strong N to NE winds are occurring in the convection. Total precipitable water imagery shows lower moisture content prevails over the central and southern Gulf. GOES Geocolor imagery and coastal surface observations from Mexico suggest that smoke or haze is occurring over portions of the SW Gulf, mainly south of 26N and west of 93W, potentially reducing visibility to 3-5 NM. Seas are 2-4 ft across the Gulf this afternoon. The weak stationary front will remain over the northern Gulf into Saturday, before being overtaken by a cold front that will stretch from near Tampa Bay, Florida to central Bay of Campeche by the end of the weekend. Behind the front, gales will develop offshore Tampico, Mexico by Saturday night. CARIBBEAN SEA... An Ashfall Advisory is in effect for La Soufriere volcano on St. Vincent. See the Special Features section above for details. A surface trough extends from 17N66W east-northeastward to beyond 20N58W. Scattered showers are present within 60 NM of the through. The East Pacific monsoon trough is enhancing scattered moderate convection in the SW Caribbean south of 11N, including over portions of NW Venezuela, N Colombia, Panama, and Costa Rica. Fresh E trades are occurring over the south-central Caribbean with moderate trades elsewhere, except for light to gentle winds south of Cuba to the Cayman Islands. Fresh SE winds are also likely occurring in the Gulf of Honduras. Seas of 4-6 ft prevail over much of the basin, except 1-3 ft south of Cuba to the Cayman Islands and Jamaica. For the forecast, fresh to strong SE winds are expected in the NW Caribbean this weekend, and then again Tue night. Fresh to strong trade winds will prevail across the south central Caribbean Sun night through early next week. ATLANTIC OCEAN... A stationary front extends from N Florida eastward to a weak 1010 mb low at 31N78W, then continues eastward of NE Florida. A surface trough also exists south of the front from 30N74W to 27N77W. Scattered moderate convection is occurring north of 28N west of 77W. Fresh to locally strong SW winds ahead of the front, mainly north of 28N between 62W-72W. Seas of 8-10 ft are present in the area of fresh to strong winds. The front will stall north of 28N through Sat then dissipate as it lifts northward through Sun. Elsewhere, weak high pressure will dominate. Over the central Atlantic, a cold front extends from 32N35W to 25N47W, where it transitions to a surface trough that continues to the NE Caribbean near 17N66W. Scattered moderate convection exists within 60 NM of the cold front. Scattered showers are also present within 60 NM of the trough. A secondary dissipating cold front extends from 32N44W to 29N50W. Winds south of 30N are mainly gentle, but some fresh winds are noted north of 30N. The cold front will dissipate by early Sat. A 1024 mb high is near 36N23W. This high pressure is expected to remain in the same general area during the next few days. Fresh to locally strong trade winds are noted from 07N-20N between the Cabo Verde Islands and 50W, where seas are 6-8 ft. $$ Landsea/Hagen