000 AXNT20 KNHC 181646 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sun Aug 18 2024 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 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 1200 UTC surface analysis and satellite imagery through 1700 UTC. ...TROPICAL WAVES... An eastern Atlantic tropical wave is analyzed with axis along 37W from 05N to 21N, moving west at 10 to 15 kt. Scattered moderate convection is observed from 05N to 10N between 22W and 35W. A tropical wave is passing through the Lesser Antilles extending from 06.5N to 20N with axis near 60W, moving west at 15 to 20 kt. Scattered showers and isolated thunderstorms are observed just west of the Lesser Antilles. A tropical wave is in the central Caribbean with axis near 74W from 08N to 19N, moving west at 10 to 15 kt. The wave is devoid of convection. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic near 19N16W and then curves southwestward to 10N34W then turns west-northwestward to 12N54W. In addition to the convection associated with the tropical wave, scattered moderate convection is seen along and within 500 nm south of the monsoon trough. ...GULF OF MEXICO... A surface trough extends from the Florida Straits westward across the central Gulf, and is acting to generate scattered moderate convection along the trough axis. There is also a diurnal surface trough in the southwestern Gulf and Bay of Campeche, with no notable convection nearby. Otherwise, a very weak pressure gradient prevails across the Gulf of Mexico, which is supporting light to gentle winds and seas of 1 to 3 ft across the basin. For the forecast, a weak pressure pattern across the Gulf will support mainly gentle to moderate breezes and slight seas through Thu night. Moderate to fresh SW winds will develop over the far NE Gulf this evening ahead of a weak cold front forecast to move into the NE Gulf early on Mon. The front will stall briefly Mon night and then move E of the area Tue afternoon. ...CARIBBEAN SEA... Please refer to the Tropical Waves section above for information on convection associated with the wave passing through the Lesser Antilles. Scattered moderate convection is observed over the southwest Caribbean in the vicinity of both the Panama Low and the eastern extension of the East Pacific monsoon trough. Ridging associated with the Azores High continues to dominate the basin otherwise, resulting in the continuation of moderate to fresh trade winds across portions of the central and the SE Caribbean. Gentle to moderate E to SE winds are over the rest of the central Caribbean with slight seas to 3 ft, while light to gentle winds are ongoing over the NW Caribbean with slight seas. For the forecast, high pressure will continue to build N of the area. The pressure gradient between the area of high pressure and low pressure over NW Colombia will support moderate to fresh trades over the central Caribbean through Thu night, increasing to fresh to strong speeds in the south-central region today through Tue night. Moderate to rough seas are forecast for the south- central basin. Elsewhere, gentle to moderate winds are expected along with slight to moderate wave heights. ...ATLANTIC OCEAN... Tropical Storm Ernesto is centered near 36.1N 62.5W at 18/1500 UTC or 510 nm S of Halifax Nova Scotia, moving NNE at 14 kt. Estimated minimum central pressure is 978 mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt. Although the center of Ernesto is N of the area, moderate to fresh winds and rough seas up to 10 ft continue to affect the offshore waters N of 29N between 56W and 70W. Away from Ernesto, a surface trough extending from the Florida Straits eastward across the central Bahamas is supporting the development of scattered moderate convection along and within 100 nm north of the trough axis. Another area of scattered showers and isolated thunderstorms is observed north of Puerto Rico and east of the Turks and Caicos Islands, generally from 20N to 23N between 63W and 67W. Otherwise, the 1027 mb Azores High, anchored at 38N 27.5W, continues to support gentle to moderate E to NE winds across much of the tropical and subtropical waters, along with seas of 4 to 7 ft. Satellite scatterometer data indicates moderate to fresh NE winds in the vicinity of the Canary Islands, along with localized seas up to 8 ft in this area. For the forecast west of 55W, large swells across the forecast waters generated by Ernesto will slowly subside through Mon. Expect moderate to fresh SW winds off northeast Florida late today into Mon, ahead of a weak cold front that will move into the area tonight. The front will briefly stall Mon night and weaken through mid week. $$ Adams