000 AXNT20 KNHC 220953 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Thu Jul 22 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 0945 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 and in the Gulf of Venezuela through early this morning. A Wednesday evening ASCAT pass measured near gale force winds from 11N-13N between 73W-77W and also in the Gulf of Venezuela. Seas will be 10-14 ft with the strongest winds across the south-central Caribbean. The gales are forecast to end prior to sunrise today. 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: Heavy rainfall is expected over Costa Rica, western Panama and southeastern Nicaragua through this weekend. The heaviest rain is expected over Costa Rica Friday night into Saturday. These rains could cause significant flooding and mudslides in some areas. Currently, scattered moderate and isolated strong thunderstorms are seen along the Caribbean coast from SE Nicaragua through western Panama. ...TROPICAL WAVES... An Atlantic tropical wave extends its axis along 40W south of 19N, moving west at 15 to 20 kt. Scattered moderate convection, likely enhanced by the monsoon trough, is noted from 07N to 12N between 28W and 39W. An Atlantic tropical wave extends its axis along 56W from 20N southward, moving westward at 10 to 15 kt. Scattered showers are noted from 10N to 13N between 50W and 56W. A tropical wave axis extends along 68W from 12N-22N, 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 the border of Senegal and Mauritania near 16N17W and extends W to 11N30W to 09N42W. The ITCZ is from 09N42W to 09N54W, then continues W of a tropical wave, from 09N56W to 09N61W. Aside from the convection described in the tropical waves section, scattered showers are along the ITCZ between 43W-47W. GULF OF MEXICO... A 1020 mb surface high pressure near 27N84W is along a weak surface ridge oriented east-west along 27N across the basin. As a result, light to gentle anticyclonic winds prevail across most of the basin. To the SW, a diurnal surface trough along 92W is moving westward in the Bay of Campeche. Winds near the trough are likely in the moderate range. Seas are 2-4 ft in the eastern Bay of Campeche and 1-2 ft elsewhere in the Gulf. The surface ridge will remain in place over the Gulf of Mexico, providing tranquil conditions through the weekend. Fresh to locally strong E to SE winds will pulse nightly NW of the Yucatan Peninsula through Fri night. 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 elsewhere across the central Caribbean and in the Gulf of Honduras. Gentle winds are found between the Cayman Islands and western Cuba. Seas over 8 ft prevail south of 17N between 72W-83W. Seas are 4-7 ft elsewhere, except 2-4 ft south of Cuba. Dry weather prevails across most of the Caribbean, except for an area of scattered showers noted near the monsoon trough mainly south of 12N between 76W and 84W. For the forecast, fresh to strong winds will continue across the central Caribbean through Fri, reaching as far north as Hispaniola adjacent waters. Fresh to strong E winds will occur in the afternoons and early evenings in the Windward Passage through Fri. Fresh to strong winds are expected in the Gulf of Honduras through the next 24 hours. ATLANTIC OCEAN... A surface ridge extends from a 1027 mb high pressure near 33N47W to 27N70W to West Palm Beach, Florida. Gentle anticyclonic winds are near the ridge axis, mainly from 25N-30N between 60W and Florida. Moderate trades prevail farther south, with fresh E winds noted north of Hispaniola on the latest ASCAT pass. Fresh trades generally prevail from 14N-24N between 35W-60W. Seas are 3-5 ft across the western Atlantic, except locally up to 7 ft just north of Hispaniola. Seas are 6-7 ft in the area of fresh trades in the tropical Atlantic. An upper-level low near 25N69W is producing a few showers to its northwest, from 23N-27N between 68W-72W. For the forecast west of 65W, fresh to strong E winds will pulse in the afternoons and evenings north of Hispaniola through Fri. Moderate to fresh trades will prevail elsewhere south of 20N. A broad trough of low pressure is forecast to move offshore of the southeastern United States coastline on Friday. Environmental conditions are forecast to be marginally conducive for some gradual development over the weekend into early next week while this system meanders offshore of the coasts of South Carolina, Georgia and northeastern Florida. Expect showers and tstorms with winds of at least moderate to fresh speeds over the weekend in that area. $$ ERA