000 AXNT20 KNHC 172335 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sun Apr 18 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: As of 2100 UTC, a cold front extends from 29N83W to 26N91W to near Tamiahua, Mexico. Fresh to strong N to NE winds behind the front are forecast to reach gale force speeds over Tampico adjacent waters tonight. Seas will build to 12 ft in that area, before winds and seas begin to diminish 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. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of West Africa near 08N13W and continues southwestward to 02N22W. The ITCZ continues from 02N22W to the coast of Brazil in South America near 00N47W. Scattered moderate convection is from the Equator to 09N between 00W and 21W, and from 01S to 04N between 43W and 50W. GULF OF MEXICO... Please see the Special Features section for details on the Gale Warning in effect for the west-central Gulf of Mexico. As of 2100 UTC, a cold front extending from 29N83W to 26N91W to near Tamiahua, Mexico continue to support scattered showers and tstms over the north-central and northeast basin. Fresh to strong N to NE winds are behind the front over the NW gulf and along the coast of NE Mexico. Aside from the shower activity, dense fog is being reported over Louisiana adjacent waters as well as Mississippi, Alabama, and Florida panhandle adjacent waters behind the front. Moderate to locally fresh southerly winds are ahead of the front over the SE gulf. The front is forecast to reach from near Cedar Key, Florida to south of Veracruz, Mexico by this evening. Winds will briefly reach gale force near Tampico, Mexico tonight west of the front. The front will stall from near Tampa Bay, Florida to the central Bay of Campeche by early next week. Looking ahead, reinforcing cool and dry air will push the front into the far southeast Gulf through mid week. CARIBBEAN SEA... La Soufriere volcano on Saint Vincent remains in a continually 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. Shallow moisture over the SW Caribbean, upper-level diffluence and the east Pacific monsoon trough continues to support scattered showers and tstms over the offshore waters of Costa Rica, Panama and SE Nicaragua. Similar shower and tstms activity is occurring over Hispaniola being supported by middle-level diffluent flow. Deep layer dry air is elsewhere, thus favoring fair weather conditions. Surface high pressure over the central Atlantic, extends a ridge axis SW to the northern and eastern Caribbean and continue to support fresh to locally strong winds over the south-central basin and Gulf of Honduras. Seas in these two regions will build to 9 ft. Moderate trade winds with seas to 7 ft are elsewhere. Fresh to strong SE winds will persist north of central Honduras through Sun, between the ridge and lower pressure over the southwest Gulf of Mexico. The ridge will shift east ahead of a weak front moving into the Gulf allowing trade winds to increase over mainly the south-central Caribbean early next week. ATLANTIC OCEAN... A stationary front extends from 31N72W to 29N75W to Daytona Beach, Florida. Middle-level diffluence and shallow moisture support scattered showers N of 28N between 60W and 70W as well as over NE Florida coastal waters. Broad surface ridging is across the remainder Atlantic waters, supporting moderate to fresh NE to E winds over the West Africa adjacent waters and over the central tropical waters. Otherwise, the remnants of a front are analyzed as a surface trough from 30N35W to 23N57W, which is supporting isolated showers and tstms within 150 nm either side of the trough. For the forecast, the front will fluctuate to the north and south over the waters between roughly Bermuda and northeast Florida through early next week, as a ridge persists across the central Bahamas. Looking ahead, the ridge will shift east by mid week ahead of a slightly stronger frontal boundary moving off the southeast U.S. coast by late Wed into Thu. $$ Ramos