206 AXNT20 KNHC 222312 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Fri Jul 23 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 2300 UTC. ...SPECIAL FEATURES... Caribbean Gale Warning: The pressure gradient between the Atlantic ridge and the Colombian/Panamanian low will support gale force winds off the coast of the Colombia overnight with 8 to 13 ft seas. The strongest winds will be within 90 to 120 nm of the Colombian coast, mainly between Barranquilla and Santa Marta. Strong to near gale force winds will also impact most of the south-central Caribbean as well. For more information, please see the High Seas Forecast issued by the National Hurricane Center at https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml Heavy Rainfall in Southern Central America: High moisture levels, persistent strong trade wind flow, and favorable conditions aloft will together support heavy rainfall for much of southern Central America through early next week. The heaviest rain is expected over the Caribbean coast of Costa Rica and southeast Nicaragua. These rains could cause significant flooding and mudslides in some areas. Currently, scattered moderate convection is noted along the Caribbean coast from SE Nicaragua through western Panama. ...TROPICAL WAVES... An Atlantic tropical wave extends its axis along 46W, south of 19N, moving W near 20 kt. Scattered moderate convection is evident from 08N to 12N between 42W and 48W. Another tropical wave is over the eastern Caribbean along 62W, south of 20N, moving W at near 15 kt. No significant convection is evident near this tropical wave. A third tropical wave from roughly the Turks/Caicos to northeast Colombia, moving W at 15 to 20 kt. This wave is not producing any notable shower activity at this time. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean near Guinea-Bissau near 12N16W and extends SW to 10N22W to 10N41W. The ITCZ continues from 10N41W to 10N45W. Scattered moderate to isolated strong convection is noted within 120 nm south of these features between 35W and 50W. GULF OF MEXICO... 1023 mb high pressure near 26N87W is the major feature over the Gulf of Mexico. This is supporting moderate E to SE winds across the west-central Gulf and Bay of Campeche with 2 to 4 ft, and light to gentle breezes elsewhere with seas 2 ft or less. No significant shower or thunderstorm activity is evident across the basin. For the forecast, the current pattern will persist and continue to provide tranquil conditions across the basin into early next week. Fresh to locally strong E to SE winds will pulse tonight NW of the Yucatan Peninsula related to a trough that forms off the west coast of the Peninsula each day. CARIBBEAN SEA... A Gale Warning is in effect for the south-central Caribbean. Please see the Special Features section for more details. A tropical wave is moving across the basin. Refer to the section above for details. Fresh to strong trades prevail across the central Caribbean, including the Windward Passage, and the Gulf of Honduras, with fresh trades in the eastern Caribbean. Gentle to moderate winds are found elsewhere. Seas are 7-9 ft in the central Caribbean and 5-7 ft elsewhere, except for 2-4 ft south of Cuba. For the forecast, the Bermuda High north of the area combined with low pressure over northern Colombia continues to support fresh to strong E winds over the central Caribbean. Gale force winds will pulse once more tonight north of Colombia and end Sat morning. Fresh to strong winds are expected to continue across the central Caribbean through Fri. Fresh to strong winds are expected in the Gulf of Honduras through tonight. ATLANTIC OCEAN... A few showers and thunderstorms are noted north of 28N between 70W and 75W, related to divergent flow aloft between an upper trough in that region and an upper low centered near 25N65W. A surface ridge extends from 1029 mb high pressure near 34N42W to east- central Florida. South of this ridge axis, a ship reported 20 kt winds near the northern approaches to the Windward Passage, hinting that fresh to strong E winds are active along the north coast of Hispaniola. This is in an area where a tropical wave is moving through, and seas may be reaching up to 6 ft. Elsewhere moderate to fresh E winds persist south of the ridge over the tropical Atlantic and 6 to 8 ft seas, highest east of leeward Islands. Gentle winds and slight seas persist along and north of the ridge axis, with 3 to 5 ft seas. Farther east, strong to near gale force winds are east of 20W, surrounding the Canary Islands. Moderate to fresh NE winds are noted elsewhere east of 35W, with 5 to 7 ft seas. For the forecast west of 65W, fresh to strong E winds will pulse in the afternoon and evening north of Hispaniola through Fri. Moderate to fresh trades will prevail elsewhere south of 20N. A low along a frontal boundary will sink southward during the weekend off the NE Florida coast. Environmental conditions are forecast to be marginally conducive for some gradual development over the weekend and into early next week while the system drifts slowly offshore of the southeastern United States. Regardless of development, showers and thunderstorms and moderate to fresh winds can be expected over the weekend off the Florida coast. $$ Christensen