000 AXNT20 KNHC 241746 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Tue Aug 24 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 1745 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 SE 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. ...TROPICAL WAVES... An Atlantic tropical wave has its axis along 27W, south of 19N, and it is moving W at 10 to 15 kt. A 1008 mb low pressure is along the wave axis near 09N. A recent scatterometer satellite pass show a broad circulation with fresh to locally strong N-NW breezes between 27W and 32W and from 08N to 12N. The wave is producing a large area of showers and thunderstorms, mainly to the W of the wave axis to 31W, and from 05N to 11N. The NHC is tracking this disturbance for possible tropical development over the next 5 days. For more details, please see the latest Tropical Weather Outlook. Another Atlantic tropical wave has its axis along 46W, south of 18N, and it is moving W at 10 to 15 kt. A recent scatterometer satellite pass reveals a sharp trough with gentle cyclonic winds. This wave is not producing any deep convection. A weak tropical wave was previously analyzed approaching the Lesser Antilles, but it appears to have dissipated based Total Precipitable Water analysis and wave diagnostics. A Caribbean tropical wave has its axis along 67W, south of 20N, and it is moving W at 10 to 15 kt. A recent scatterometer satellite pass indicates that it has a broad curvature with fresh to strong trades covering most of the central and eastern Caribbean. This system is also producing a large area of showers and thunderstorms, especially from 10N to 15N, affecting the ABC islands and NW Venezuela, and between 62W and 74W. The NHC is also tracking this disturbance for possible tropical development over the next 5 days. For more details, please see the latest Tropical Weather Outlook. A second Caribbean tropical wave has its axis along 87W, south of 20N, and it is moving W at 10 to 15 kt. The wave extends from the Gulf of Honduras, across Central America, to the Eastern Pacific. The wave is not producing any deep convection on the Caribbean side. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean through the coast of Mauritania near 20N16W, passing near the Cabo Verde Islands, and continues westward to 06N29W to 11N42W and to 08N49W. The ITCZ then extends from 08N50W to 12N60W. Most of the convective activity across the region is related to the tropical waves. ...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 30N85W in the Florida Panhandle to 29N92W. A few showers are noted along the weak trough. The other cluster of scattered moderate convection is seen in the SW Bay of Campeche, mainly within 70 nm of the coast of Veracruz, in association with the northernly end of a tropical wave along 96W. A recent scatterometer satellite pass observed fresh to locally strong N-NE winds with these storms. Gentle to moderate anticyclonic winds prevail across the rest of the Gulf. Seas of 2-4 ft are present in the Bay of Campeche and the Florida Straits, while 1-2 ft is prevalent elsewhere. For the forecast, high 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 Wed night. An area of low pressure is expected to form in the western Caribbean late this week, and this system could approach the Yucatan Peninsula or Belize by Sat. There is a medium chance of tropical cyclone formation within the next 5 days. An increasing pressure gradient between high pressure over the Gulf waters and the possible tropical system over the western Caribbean will result in fresh to strong easterly winds over the SE and south- central Gulf during the upcoming weekend. ...CARIBBEAN SEA... Two tropical waves are moving westward across the Caribbean Sea. Please, see the Tropical Waves section for details. Scattered moderate to isolated strong convection is noted in the SW Caribbean Sea from the coast of Nicaragua to northern Panama. Satellite imagery suggest that confluent winds, abundant moisture and the presence of the eastern portion of the East Pacific monsoon trough is resulting in the large area of convection. As mentioned in the tropical wave section, fresh to strong trades are prevalent across the central and eastern Caribbean, including the entrance to the Windward Passage. Moderate to fresh winds are present in the rest of the basin. Seas are 6-9 ft in the central and eastern Caribbean, with the highest seas occurring off the NW coast of Colombia. The rest of the Caribbean is observing seas of 3-6 ft. For the forecast, fresh to locally strong trade winds will dominate most of east and central Caribbean through midweek with seas in the 7 to 8 ft range. Fresh to locally strong winds are also expected in the Windward passage and in the lee of Cuba through tonight. A tropical wave over the eastern Caribbean Sea along 67W is expected to form a broad area of low pressure over the southwestern Caribbean later this week. Conditions are forecast to be conducive for development, and a tropical depression could form late this week or this weekend while the system moves northwestward over the northwestern Caribbean Sea, toward the Yucatan Peninsula or Belize by Sat. ...ATLANTIC OCEAN... Two tropical waves are moving westward between the W coast of Africa and the Lesser Antilles. Please, see the Tropical Waves section for details. A broad subtropical ridge maintains dominance of the tropical Atlantic. A 1009 mb low pressure is located near 22N46W is moving NW at 10 to 15 kt. The system is producing a small area of showers and thunderstorms near the center. A recent scatterometer satellite pass show strong to near gale-force winds over the northern and eastern semicircle, extending up to 200 nm from the center. Seas in the area are in the 6-9 ft range. The NHC is tracking this disturbance for possible tropical development over the next 5 days. For more details, please see the latest Tropical Weather Outlook. Northwest of the low, a weak surface trough extends from a weakening stationary front north of the area to 24N54W. Scattered moderate showers are noted SE of the trough from 24N to 29N. The combination of a surface trough NE of the Bahamas and an upper level low is causing a large area of scattered moderate convection from 24N to 29N and between 67W and 73W. The storms produced an expansive outflow boundary that moved across the SE Bahamas, eastern Cuba and Hispaniola, but it has dissipated as of 1725 UTC. The recent scatterometer satellite pass captured a broad area of strong to near gale-force N-NE winds from the coasts of Hispaniola and eastern Cuba to 25N and betwen 67W to 77W. The strongest winds were near the northern coast of Hispaniola and likely generated by the outflow boundary. Seas W of 60W are in the 4-8 ft range. Also, a weak trough over the SE United States is generating some showers off NE Florida, mainly north of 28N and between 77W and 80W. The rest of basin enjoys fairly tranquil weather conditions. The pressure gradient between the subtropical ridge and lower pressure associated with the disturbance in the eastern Atlantic is causing fresh to strong NE winds from 15N to 27N and between the coast of Africa to 33W. Seas in this region are in the 5-8 ft range. Gentle to moderate winds and 3-6 ft seas prevail in the rest of the basin. For the forecast W of 65W: A surface trough east of the Bahamas will move westward, bringing strong NE to E winds over the central Bahamas tonight. By Thu morning, the surface trough will extend from 30N78W to the western tip of Cuba, bringing fresh to strong E winds to the east of northern Florida before the trough weakens by late Thu. Otherwise, a 1021 mb high pressure located near Bermuda will dominate the remainder of the forecast region through at least Wed. Fresh to locally strong winds are expected N of Hispaniola including the approaches to the Windward Passage through tonight. Fresh to locally strong winds will continue to pulse north of Hispaniola during the evening hours through Sat night. Expect increasing winds across the waters between Cuba and the Bahamas by the end of the week as a tropical system develops over the NW Caribbean. $$ DELGADO