000 AXNT20 KNHC 251022 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Wed Aug 25 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 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...SPECIAL FEATURE... Heavy Rainfall in southern Central America: A broad area of low pressure is expected to form over the SW Caribbean Sea later this week, resulting in an increase in moisture and unstable conditions across southern Central America. Heavy rainfall is expected across eastern Nicaragua, Costa Rica, Panama, and NW Colombia through early in the weekend. The heaviest precipitation is forecast to affect southern Costa Rica and western Panama late this week. These rains could cause significant flooding and mudslides in some areas. Please, monitor the latest forecasts for your local or national meteorological service. ...TROPICAL WAVES... The axis of a tropical wave is near 31W, south of 19N, moving W at 10 to 15 kt. A 1008 mb low pressure is along the wave axis near 10N31W. Scattered moderate to isolate strong convection is noted NW of the low center from 12N to 15N between 31W and 35W. Some development of this system is possible over the next several days while it moves west-northwestward at 10 to 15 kt over the eastern tropical Atlantic. Upper-level winds are forecast to become less conducive for development by this weekend. For more details, please see the latest Tropical Weather Outlook. The axis of a tropical wave is near 51W, south of 19N, moving W at 10 to 15 kt. There is no significant convection associated to this wave. The axis of a tropical wave is near 72W, south of 20N, moving W at 10 to 15 kt. A 1006 mb low pressure is along the wave axis near 13N72W. Clusters of moderate to isolated strong convection are noted on the west side of the low center, particularly from 11N to 14N between 72W and 74.5W. This convective activity is affecting the Guajira peninsula in Colombia. This disturbance is being monitored for possible tropical cyclone development over the western Caribbean Sea in a couple of days. For more details, please see the latest Tropical Weather Outlook. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean through Senegal near 14N17W and continues to 10N31W to 05N35W. The ITCZ then extends from 05N35W to 07N48W. Aside from convection noted in the tropical waves section, scattered moderate isolated strong convection is observed within 90-120 nm of the coast of Africa from 04N to 11N. This convective activity is likely ahead of the next tropical wave approaching the W coast of Africa. ...GULF OF MEXICO... High pressure continues to dominate the weather conditions across the Gulf of Mexico. A surface trough in the northern Gulf extends from the Florida Panhandle to 28N92W. Scattered showers and isolated thunderstorms are seen along the trough axis. Light to gentle winds are noted over the northern Gulf waters, mainly N of 27N with gentle to moderate winds prevail elsewhere. Seas are in the 3-5 ft range over the SE Gulf, and in the eastern Bay of Campeche with seas of 1-3 ft elsewhere. For the forecast, a surface trough will move into the eastern Gulf tonight into Thu morning, bringing fresh NE to E winds. Otherwise, high pressure pressure will dominate the basin through Fri, producing mainly gentle to moderate E to SE winds. Fresh winds will pulse west of the Yucatan Peninsula tonight and again Thu night. A broad area of low pressure is expected to form over the western Caribbean Sea in a couple of days. Environmental conditions are forecast to be conducive for development, and a tropical depression is likely to form late this week or this weekend while the system moves northwestward over the northwestern Caribbean Sea, near or across the Yucatan Peninsula of Mexico, and into the western Gulf of Mexico by Sunday. Based on the forecast, expect increasing winds and seas across the Gulf waters during the upcoming weekend. ...CARIBBEAN SEA... Satellite derived wind data indicate fresh to strong trade winds across the central Caribbean, and fresh to locally strong winds in the Windward passage, and in the Gulf of Honduras. Moderate to fresh winds are noted elsewhere. Seas are in the 6-9 ft range across the central Caribbean, but mainly between 70W and 75W. Seas are in the 3-4 ft range over the NE Caribbean, and 4-6 ft elsewhere. Clusters of moderate to strong convection are over the SW Caribbean, mainly S of 12N, in association with the eastern Pacific monsoon trough, that extends from northern Colombia to Costa Rica. For the forecast, fresh to locally strong trade winds will dominate most of east and central Caribbean today. A broad area of low pressure is expected to form over the western Caribbean Sea in a couple of days from a tropical wave currently located over the central Caribbean Sea along 72W. Environmental conditions are forecast to be conducive for development, and a tropical depression is likely to form late this week or this weekend while the system moves northwestward over the northwestern Caribbean Sea, and near or across the Yucatan Peninsula of Mexico. Based on the forecast, winds and waves will likely increase between 77W and the Yucatan Peninsula Fri and Sat. ...ATLANTIC OCEAN... A surface trough is E of the Bahamas S of 28N along 71W. This trough is a reflexion of an upper-level low that is moving westward. Scattered showers and thunderstorms are associated with the trough and cover the waters from 24N to 28N between 70W and 80W. Moisture related to this trough will reach South Florida by this afternoon increasing the likelihood of showers and thunderstorms. Fresh to strong NE winds are ahead of the trough axis over the central Bahamas and the Old Bahama Channel reaching the coast of Cuba. Seas of 8-9 ft are associated with these winds E of the Bahamas. For the forecast W of 65W: the surface trough located along 71W will reach the NW Bahamas this evening and move into the eastern Gulf of Mexico late tonight into Thu morning. Fresh to strong NE winds are expected ahead of the trough axis. Otherwise, high pressure located just N of the forecast region will dominate the SW N Atlantic through Sat. Fresh to locally strong winds are expected to pulse N of Hispaniola during the evening hours through Sat night. A broad trough of low pressure remains over the central Atlantic and extends from 31N50W to 21N52W. Fresh to strong SE winds are noted per scatterometer data on the E side of the trough axis. A low pressure is analyzed along the trough near 25N52W. This system is producing disorganized showers and thunderstorms over the waters N of 25N between 50W and 53W. Only slow development of this system is expected during the next day or so due to unfavorable upper-level winds. Afterwards, environmental conditions are expected to become more conducive for development, and a tropical depression is likely to form late this week or this weekend while the system turns eastward over the central Atlantic. For more details, please see the latest Tropical Weather Outlook. The remainder of the Atlantic forecast waters is under the influence of a ridge. The pressure gradient between the ridge and lower pressures near the monsoon trough supports an area of moderate to fresh NE to E winds roughly from 15N to 25N E of 40W, and between the Canary Islands and the coast of Morocco and Western Sahara. $$ GR