000 AXNT20 KNHC 231026 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 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 0600 UTC surface analysis and satellite imagery through 0930 UTC. ...SPECIAL FEATURES... Caribbean Gale Warning: The pressure gradient between the broad Atlantic ridge and the Colombian/Panamanian low will support gale force winds along the coastal waters of Colombia through 1200 UTC, with seas building to 9 to 12 ft. The strongest winds are expected within 90 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 through this morning as well, before winds begin to gradually diminish during the next 24 hours. 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 is analyzed along 54W, south of 19N, moving W near 15 to 20 kt. Scattered moderate convection is evident along the ITCZ south of 12N between 40W and 53W. A broad area of Saharan Air accompanies this wave, extending from 12N to 24N from 60W to beyond 40W. Another tropical wave is over the eastern Caribbean along 67W, south of 20N, moving W at near 15 kt. Scattered moderate convection is evident behind the wave across the SE Caribbean south of 12N, associated with the ITCZ. A third tropical wave is analyzed along 80W, from 13N to 25N, moving at 10 to 15 kt. No significant cloudiness or convection is associated with this wave. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean near Guinea-Bissau near 11.5N16W and extends SW to 10N20W to 12N31W. The ITCZ continues from 12N31W to 12N50W. Scattered moderate isolated strong convection is noted within 240 nm south of these features between 30W and 50W. GULF OF MEXICO... 1022 mb high pressure near 27N90W is the dominant feature over the Gulf of Mexico. This is supporting moderate E to SE winds across the west-central Gulf and Bay of Campeche, where seas are 2 to 4 ft, and light to gentle breezes elsewhere with seas 2 ft or less. Dry and generally stable conditions aloft dominate most of the basin this morning. A cluster of scattered showers and thunderstorms across SW Florida has drifted west into the offshore waters north of Key West and diminished significantly during the past few hours. The Bermuda High extends across Florida to the second 1022 mb high across the N central Gulf of Mexico. This high pressure ridge will drift westward over the weekend and become separated from the Bermuda high, as low pressure meanders offshore of the Atlantic waters of Florida. This will maintain generally tranquil marine conditions across the Gulf through early next week. CARIBBEAN SEA... A Gale Warning is in effect for the south-central Caribbean. Please see the Special Features section for more details. Fresh to strong trades prevail across most of the central Caribbean to 80W, 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 7-11 ft in the central Caribbean and 5-7 ft elsewhere, except for 2-4 ft south of Cuba. Fresh to strong easterly trades are building in across the NE Caribbean behind the tropical wave along 67W, and will bring scattered afternoon convection to the area today. High pressure centered across the central Atlantic extends W-SW to central Florida and is combining with low pressure over N Colombia to support fresh to strong E winds over the central Caribbean. Gale force winds north of Colombia will end early this morning. The pressure gradient south of the ridge will support fresh to strong winds across the central Caribbean today. The ridge will weaken west of 75W this afternoon through early next week as a weak frontal system and low pressure move offshore of Georgia and Florida and meander through the weekend, weakening the pressure gradient across the basin. ATLANTIC OCEAN... A few clusters of showers and thunderstorms are noted between 28N and 31N, from the Florida coast to 75W, to the south of a frontal boundary sinking southward toward these northern waters. A broad surface ridge extends from 1027 mb high pressure near 34N41W to central Florida. Fresh to strong E winds are active along the north coast of Hispaniola to 21N. Elsewhere moderate to fresh E winds persist south of the ridge, south of 23N over the tropical Atlantic, where seas are 6 to 8 ft in easterly swell. 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. Moderate to fresh trades will prevail south of 25N through Sun as the ridge generally remains in place. Low pressure along a frontal boundary just north of the area will sink southward today through the weekend off the Georgia and NE Florida coasts. 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 as the ridge remains in place. A large tropical wave approaching the Lesser Antilles will move into the E Caribbean and adjacent Atlantic waters tonight through the weekend to bring fresh E to SE winds and seas of 5-8 ft. $$ Stripling