000 AXNT20 KNHC 121707 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Mon Jul 12 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 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 Atlantic tropical wave is along 38W from 11N southward and moving W at 15 to 20 kt. Scattered moderate convection is seen from 08N to 11N between 37W and 39W. Another weaker Atlantic tropical wave is near 50W from 09N southward and moving W near 15 kt. Scattered moderate convection is noted ahead of the wave axis to the coast of Guyana from 06N to 09N. A robust Caribbean tropical wave extends from Haiti to northeast Colombia, moving W at 10 to 15 kt. Aided by upper- level divergent winds, scattered to numerous showers and thunderstorms are present across the Turks and Caicos Islands, Dominican Republic and over waters south of Hispaniola . The Caribbean tropical wave previously located over Honduras, Nicaragua and Costa Rica has moved in the E Pacific and will be included in the Pacific Discussion. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Guinea-Bissau near 11N16W to 08N28W to 07N37W. The ITCZ then continues from 07N39W to 07N47W. In addition to the convection listed in the Tropical Wave section, scattered moderate to isolated strong convection is evident near the monsoon trough from 05N to 10N between 15W and 30W, and from 08N to 11N between 40W and 45W. ...GULF OF MEXICO... A surface ridge extends west-southwestward from northern Florida across the northern Gulf to South Texas. A scatterometer pass from 1500 UTC confirmed this pattern is supporting mostly gentle to moderate E to SE winds over most of the basin. Seas are mainly 2 to 4 ft. A few showers and thunderstorms are noted over the northwestern Gulf, the Straits of Florida, and over the warmer Loop Current of the south-central Gulf. For the forecast, the gentle to moderate SE winds will persist across most of the Gulf, south of the surface ridge. The ridge will lift just north of the area through today, maintaining gentle to moderate winds and slight to moderate seas through Fri. The exception will be fresh to occasionally strong winds off the northwest Yucatan Peninsula and eastern Bay of Campeche during overnight hours through mid week, related to the surface trough that forms during the late afternoon each day. ...CARIBBEAN SEA... Please refer to the Tropical Waves section above for details on convection in the basin. Scatterometer data from this morning noted fresh trades across most of the eastern and central Caribbean, with locally strong winds in the south-central Caribbean offshore of Colombia. Maximum seas are estimated to be 9 ft in the south-central Caribbean, mainly off the coast of Colombia, and 6 to 8 ft over the eastern Caribbean where fresh tradewinds follow the tropical wave moving across the basin. Moderate E to SE winds and 3 to 5 ft seas are noted over the northwest Caribbean. In addition to the convection mentioned in the Tropical Wave section, scattered moderate to isolated strong convection is ongoing off Costa Rica and southeastern Nicaragua. For the forecast, the tropical wave reaching from Haiti to northeast Colombia will move west of the basin into mid week. High pressure centered north of the region will build in the wake of the tropical wave, supporting strong tradewinds and building seas into Wed, including strong nocturnal NE winds across the Windward Passage Tue night into Wed. Winds and seas will diminish through Fri. ...ATLANTIC OCEAN... Please see the Tropical Waves and Monsoon Trough/ITCZ sections above for information on convection across the basin. A surface ridge extends from the central Atlantic across Bermuda to the central Florida coast. This pattern is supporting gentle to moderate E to SE trade winds north of 25N west of 35W with 3 to 5 ft seas over open waters. Fresh trades are noted south of 25N west of 35W to 60W with 6 to 9 ft seas. Fresh to locally strong E winds are south of 25N and west of 60W over waters surrounding the Greater Antilles with 4 to 6 ft seas. Divergence aloft associated with an upper low now centered over Grand Bahama Island is supporting clusters of scattered moderate to isolated strong convection over the Cay Sal area of the Bahamas and across the southern Bahamas and Turks and Caicos Islands. For the forecast, the surface ridge from the north-central Atlantic through Bermuda to central Florida will lift north to along 32N through Tue. An active tropical wave over Haiti will move quickly westward across the central Caribbean and bring a surge in wind and waves to the Atlantic waters north of Hispaniola and Cuba and across the Turks and Caicos Islands and southern Bahamas late today and Tue. Strong winds will continue to pulse off Hispaniola and into the Windward Passage Tue night into Wed. Winds and seas will diminish across the region through Fri as the high pressure weakens. $$ Mora