000 AXNT20 KNHC 252149 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Mon Jul 26 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 1800 UTC surface analysis and satellite imagery through 2130 UTC. ...SPECIAL FEATURES... A 1012 mb low is centered near 30N79W. An Air Force Reserve reconnaissance aircraft flying over the low pressure found fresh to strong winds near the center. A recent scatterometer satellite pass showed mainly fresh winds extending well to the north of the low. Disorganized shower and thunderstorm activity persists mainly over the southern part of its circulation. Environmental conditions are marginally conducive for development, and there is a medium change a tropical depression could still form later today or early Monday while the low drifts westward or west-northwestward toward the northeast coast of Florida. Interests in Florida should continue to monitor the progress of this system. Please read the latest Tropical Weather Outlook at hurricanes.gov for more information. Heavy rainfall is expected to continue in Southern Central America, particularly in Panama and Costa Rica and perhaps southern Nicaragua. High moisture content, persistent monsoon flow, and favorable conditions aloft will continue to support scattered to numerous strong convection capable of producing torrential rain through Monday. Heavy rainfall in these areas could cause significant flooding and mudslides. ...TROPICAL WAVES... An Atlantic tropical wave is near 23W/24W from 05N to 20N, moving westward at 10 kt. Scattered moderate convection is noted from 07N to 09N between 21W and 24W. An Atlantic tropical wave along 579 south of 12N moving west at 15-20 kt, moving through Guyana and approaching Barbados. There is reasonable evidence of this wave in Hovmoller diagrams going back several days. Recent satellite- derived wind data from the lower levels of the atmosphere hints the wave is restricted to the deep tropics. Scattered moderate convection is evident from 08N to 12N between 52W and 60W. A Caribbean Sea tropical wave is along 73W from central Hispaniola to northeast Colombia, moving W at 10 kt. The tropical wave is moving west of an upper level low centered off northern Haiti. Dry, subsident air in the northerly flow on the west side of this upper low, along with lingering, dry Saharan air, are inhibiting any major convection near the tropical wave. A Caribbean Sea tropical wave is near 82W from western Cuba to western Panama, moving W at 10 to 15 kt. Convection associated with this wave is confined to near the monsoon trough, S of 12N and is described below. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean along the coast of Senegal near 13N17W to 11N18W to 08N35W. The ITCZ continues from 08N35W to 08N52W. No significant convection is evident along these features at this time. The eastern Pacific monsoon trough extends from off the coast of Colombia near 12N73W to near the Costa Rica/Panama border near 10N82W. Scattered moderate convection is noted within 60 nm either side of this monsoon trough axis, with numerous moderate to heavy rainfall observed over western Panama at this time. ...GULF OF MEXICO... A surface trough extends from Cape Sable in southwest Florida to the central Gulf near 26N90W. Farther west, 1016 mb high pressure is centered near 28N94W. A few showers are likely ongoing the trough. Light to gentle winds and slight seas prevail across the Gulf. For the forecast, showers and thunderstorms will persist south of the trough, forecast to drift northward over the next couple of days as the low pressure located about 130 nm east of Daytona Beach, Florida, drifts westward or west-northwestward toward the northeast coast of Florida. At the same time, the high pressure will move toward SE Louisiana. ...CARIBBEAN SEA... Refer to the Tropical Waves section above for more information on convection across the Caribbean Basin. Overall, a relatively benign pattern continues across the Caribbean today. There are scattered showers and thunderstorms over the far southwest Caribbean, south of 12N, from western Colombia to Costa Rica, to include the coast of Panama, posing a risk of flooding. A few showers are possible off the coast of northeast Colombia and northwest Venezuela, as far east as Curacao. But no significant showers or thunderstorms are noted elsewhere. Light breezes and slight seas are noted over the northwest Caribbean, and gentle to moderate trade winds with 2 to 4 ft seas elsewhere. The trade wind flow is lighter than usual, related in part to a relatively weaker subtropical ridge north of the area. For the forecast, the current pattern will continue past mid week, supporting gentle to moderate trade winds across the basin through Thu, with the exception of moderate to locally fresh winds near the coast of Colombia. Winds will increase across the E and central Caribbean Thu night into Fri as the Atlantic ridge builds westward in the wake of the low pressure located E of Florida. ATLANTIC OCEAN... See the Special Features section for more information on the low east of Florida and the Tropical Waves section for information on the wave off the African coast. Clusters of showers and thunderstorms are noted over the Atlantic north of Puerto Rico and east of the Bahamas, specifically from 20N to 25N between 62W and 68W. This activity is tied to upper level divergence between an upper low over the Turks/Caicos Islands and an upper trough in the northwest flow aloft farther to the northeast over the central Atlantic. A weak surface trough is analyzed in this area of convection, from 22N69W to 28N63W. Another trough is analyzed farther east, from 22N to 28N between 45W and 50W. The troughs are south of a 1028 mb high pressure near 39N35W. Earlier scatterometer satellite passes indicated fresh E winds near western trough. This is evidence of a broader area of fresh winds from 18N to 25N between 55W and 70W between the trough and the ridge, with seas estimated to be 5 to 7 ft. Similarly moderate to fresh winds and 5 to 7 ft seas are likely between the eastern trough and the ridge, from 25N to 30N between 35W and 50W. Aside from fresh to strong winds near the Cape Verde Islands and off Morocco, this pattern is support generally moderate trade winds and 4 to 6 ft seas across the basin. For the forecast for the waters west of 65W, other than what is described in the Special Features section above regarding the low pressure off northeast Florida, the area of showers and thunderstorms will move northward across the waters east of the Bahamas through Tue. $$ Christensen