000 AXNT20 KNHC 152318 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Wed Aug 16 2023 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...TROPICAL WAVES... The axis of a tropical wave is over west Africa near 15W from 04N to 18N, moving W at 10-15 kt. Numerous moderate with isolated strong convection is occurring from 05N to 18N between 25W and the west coast of Africa. The tropical wave is forecast to move off the west coast of Africa tonight or early Wednesday. Some slow development of this system is possible later this week or over the weekend while it moves generally west-northwestward or northwestward across the eastern Atlantic. Environmental conditions are expected to become unfavorable for development by early next week. There is a low chance for tropical cyclone development over the next 7 days. The axis of an Atlantic Ocean tropical wave is near 35W, from 18N southward, moving W at 15 kt. Scattered moderate convection is noted from 07N to 16N between 31W and 40W. Development, if any, of this system should be slow to occur while it moves generally west-northwestward at about 15 mph across the tropical Atlantic through the end of the week. There is a low chance for tropical cyclone development over the next 7 days. The axis of an Atlantic Ocean tropical wave is near 58W, from 21N southward, moving W at 15-20 kt. Scattered moderate convection is noted from 11N to 13N between 57W and 60W, including over Trinidad and Tobago. The axis of a Caribbean Sea tropical wave is near 82W, from 19N southward through Panama and into the east Pacific, moving W at 15-20 kt. Upper-level diffluence to the east of an upper-level low centered over Belize and northern Guatemala is enhancing scattered moderate isolated strong convection across the western Caribbean from 10N to 28N between 80W and 86W. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through coastal Mauritania near 18N16W to 13N35W to 09N55W. See the Tropical Waves section above for a description of showers and thunderstorms. GULF OF MEXICO... A high pressure ridge stretches across the central Gulf of Mexico from east to west. Weak surface troughing is over the Bay of Campeche, where moderate E winds prevail along with 3-4 ft seas. Light to moderate winds prevail elsewhere with 1-3 ft seas. Scattered thunderstorms are seen over the NE Gulf from 24N to 30N and west of 85W. Isolated showers and tstorms are near the coast of Mexico between Veracruz and Tampico. A surface trough over the eastern Straits of Florida is helping scattered thunderstorms persist across the western Straits of Florida and SE Gulf. A narrow upper- level trough is also producing some cloudiness and isolated showers and tstorms across the west-central Gulf. For the forecast, a trough will move off the Yucatan Peninsula each night through late week, supporting fresh winds off northwest Yucatan. Elsewhere, a ridge over the Gulf will support mostly gentle to moderate winds and slight seas across the basin through Sat. CARIBBEAN SEA... See the Tropical Waves section above for a description of showers and thunderstorms occurring across the basin. No significant precipitation is noted north of 12N and east of 77W, due to dry Saharan dust over the eastern two-thirds of the Caribbean, as noted on the GOES-16 CIMSS Saharan Air Layer Tracking Product. Earlier ASCAT data depicted fresh E trade winds across the eastern and central Caribbean. Recent buoy and altimeter data show seas of 6 to 7 ft across much of the basin, east of 80W. In the south- central basin, off the coast of Colombia, earlier ASCAT shows strong ENE winds with seas likely range 7 to 8 ft. Moderate or weaker winds and 2 to 5 ft seas prevail across the western Caribbean. For the forecast, ridging over the western Atlantic will support fresh to locally strong winds across mainly the south-central Caribbean into Wed. Moderate winds and seas will prevail otherwise. ATLANTIC OCEAN... A surface trough is moving westward over the eastern Straits of Florida, from 27N7.5W to 24N81W. Scattered thunderstorms are noted from 22N to 269, and west of 72W through the Straits of Florida. Scattered moderate convection is also noted offshore NE Florida, north of 28N and W of 80W. An upper-level low centered near 26N68W is only able to induce isolated showers and tstorms from 22N to 29N between 65W and 70W as a large plume of dry Saharan dust has recently caught up with the upper-low. Surface ridging dominates the remainder of the basin, anchored by a 1024 mb high pressure center near 34N41W. A surface ridge axis extends WSW from that high to the NW Bahamas. Moderate to fresh NE to E trade winds from 15N to 26N between 35W and 60W, where seas are 6 to 8 ft. Earlier ASCAT data depicted moderate to fresh ESE trades north of Hispaniola through the SE Bahamas and in the Windward Passage, where seas are likely 4 to 5 ft. Gentle to moderate wind speeds are farther north, closer to the ridge axis. Over the far NE Atlantic, from the Canary Islands to the coast of Western Sahara, fresh to strong NE winds and seas of 7 to 8 ft prevail. Of note, a dry airmass due to Saharan dust covers much of the basin from 13N to 27N, and east of 70W. For the forecast W of 55W, fresh to locally strong winds will pulse off Hispaniola this evening. Fresh E winds will form S of 25N starting Thu. A cold front will approach the NW waters then stall, but fresh SW winds can be expected Thu and Thu night in the NW waters. Gentle to moderate winds will prevail elsewhere. $$ AReinhart