000 AXNT20 KNHC 162323 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Thu Aug 17 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 approaching the Cabo Verde Islands along 26W, from 17N southward, moving W at 15 kt. This tropical wave is producing a large area of disorganized showers and thunderstorms. This system is forecast to move toward the west- northwest at about 15 mph, with an area of low pressure expected to form in a day or so just to the west of the Cabo Verde Islands. Further development of the low is possible, and a tropical depression could form over the weekend before environmental conditions become unfavorable early next week. This system has a low chance of developing in 48 hours and a medium chance in 7 days. An axis of a tropical wave is in the central Atlantic along 42W, from 16N southward, moving W at 15 kt. Scattered moderate and isolated strong convection is noted from 09N to 15N between 39W and 46W. Environmental conditions appear conducive for gradual development of this system, and a tropical depression could form during the next several days while moving toward the west or west- northwest at about 10 kt across the central tropical Atlantic. This system has a low chance of developing in 48 hours and a medium chance in 7 days. The axis of a tropical wave is in the E Caribbean near 65W, from 19N southward, moving W at 15 kt. Convection previously associated with this wave has generally diminished today. ...MONSOON TROUGH/ITCZ... The monsoon trough passes near coastal Senegal near 15N17W to 11N29W to 10N47W. The ITCZ continues from 10N47W to 10N61W. Scattered moderate to isolated strong convection is noted from 07N to 17N between 20W and 32W. Scattered moderate convection is noted from 06N to 13N between 49W and 59W. GULF OF MEXICO... Scattered moderate to isolated strong convection is noted over the eastern Bay of Campeche. Otherwise, a stationary front is noted just inland of the northern Gulf coast, with a weak pre- frontal trough noted along 28N from offshore the Florida Panhandle to the NW Gulf. Scattered moderate to isolated strong convection 22N and E of 96W. Despite these features, weak high pressure dominates the basin, providing light and variable winds and seas of 1 to 2 ft. For the forecast, the surface trough will continue to support isolated thunderstorms across the N-central and NE Gulf tonight and tomorrow. A surface ridge over the central Gulf will support mostly gentle to moderate winds and slight seas across the basin through the weekend. Looking ahead, a broad area of low pressure could form in the central or W Gulf by the beginning of next week. CARIBBEAN SEA... Scattered moderate convection is noted near the Windward Islands, otherwise dry conditions prevail. Fresh to locally strong trades are noted in the central Caribbean, with moderate winds in the eastern Caribbean. Gentle winds are noted in the NW basin and S of the eastern extension of the East Pacific monsoon trough along 10N in the far SW Caribbean. Seas are 5 to 7 ft in the central Caribbean, and 3 to 5 ft elsewhere, lesser in the lee of Cuba. For the forecast, fresh to locally strong tradewinds will prevail across the central Caribbean through tonight. The pressure gradient between the Bermuda High and the Colombian Low will loosen by tomorrow morning, resulting in a slight decrease in winds over the area for the next few days. Gentle to moderate tradewinds will prevail elsewhere. ATLANTIC OCEAN... The dominating feature in the basin is the Bermuda to Azores ridge. This is leading to mainly gentle E winds N of 25N, with the gradient between the ridge and the ITCZ and monsoon trough leading to moderate to fresh trades S of 25N. Some moderate to fresh SW winds are occurring N of the Bahamas, as an eastward moving front along the Mid-Atlantic U.S. coast passes N of the waters. Scattered moderate to isolated strong convection is N of 24N and W of 70W to the coast of Florida. Some fresh to locally strong winds have developed within about 100 nm of the center of a 1009 mb low pressure to the SW of the Cabo Verde Islands, that is depicted in more detail in the tropical waves section above. Other convection associated with the monsoon trough and tropical waves is also described in the section above. Seas across the basin are mainly 5 to 8 ft, with areas NW of a 31N60W to Turks and Caicos line having somewhat lower seas of 3 to 5 ft. For the forecast W of 55W, fresh to locally strong tradewinds will pulse off Hispaniola each evening through the next several days. Fresh tradewinds will develop south of 25N starting Thu and diminishing again on Sat. A cold front will approach the NW waters then stall, but fresh SW winds ahead of the cold front can be expected Thu and Fri in the NW waters. Gentle to moderate winds will prevail elsewhere. $$ AReinhart