000 AXNT20 KNHC 201755 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Tue Jul 20 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 1715 UTC. ...SPECIAL FEATURES... Caribbean Gale Warning: The pressure gradient between the subtropical high and Colombian Low/Monsoon Trough will support gale force winds tonight off the coast of the Colombia in the south central portion of the basin, including the Gulf of Venezuela. Seas will build to 8-12 ft tonight, increasing further to 9-13 ft by Wednesday morning. For more information, please see the High Seas Forecast issued by the National Hurricane Center at https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml ...TROPICAL WAVES... An Atlantic tropical wave extends its axis along 26W and south of 21N, moving west at 10 to 15 kt. Scattered moderate convection is noted from 07N to 11N between 25W and 30W. An Atlantic tropical wave extends it axis along 47W from 20N southward, moving westward at 10 to 15 kt. This wave is convectively inhibited by subsidence and dry air associated with the Saharan Air Layer. The northern extension of a tropical wave passes through the Gulf of Honduras, along 87W and south of 18N. This tropical wave is moving west at 10 to 15 kt. Scattered showers are noted south of 18N from west of 84W. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from 13N17W to 08N40W. The ITCZ extends from 07N49W to the coast of Guyana near 07N58W. Scattered moderate convection is noted near the monsoon trough from 05N to 10N east of 21W. Scattered showers are along the ITCZ, mainly within 60 nm of the coast of Guyana. GULF OF MEXICO... A surface trough recently moved offshore into the NW Gulf, and as of 1500 UTC extends from the coast of Louisiana near 29N91W to the Texas coast near 27N97W. Scattered moderate convection is noted within 80 nm of either side of the trough. Additionally, surface observations show near gale force winds accompanying this feature. Another surface trough is analyzed in the Bay of Campeche from 22N91W to 19N93W, with no convection at this time. Elsewhere, surface ridging prevails across the Gulf, with gentle anticyclonic winds and seas of 1-3 ft. For the forecast, the ridge will continue to sink southward through the forecast period, providing tranquil conditions across the Gulf of Mexico for the remainder of the week. Moderate to fresh E to SE winds will pulse Wed night to the NW of the Yucatan Peninsula through the end of the week. CARIBBEAN SEA... Please refer to the Special Features section for details on a Gale Warning for the south central Caribbean. Scatterometer data depict strong trades prevailing across the south central portion of the basin south of 14N between 70W and 82W, with 7-11 ft seas. Elsewhere in the basin, moderate to fresh trades prevail with 5-8 ft seas, except in the NW Caribbean where trades are gentle to moderate with 2-4 ft seas. For the forecast, the Bermuda High north of the area combined with low pressure N Colombia will support fresh to strong NE to E winds over the central Caribbean through most of the week. Expect an increase in areal coverage of strong wind speeds reaching to gale force near the coast of Colombia and the Gulf of Venezuela tonight. Fresh to strong winds will reach 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 midweek. Fresh to strong winds are expected to pulse in the Gulf of Honduras Wed night and Thu night. ATLANTIC OCEAN... High pressure centers at 32N54W and 31N36W support gentle to moderate anticyclonic winds across the tropical Atlantic. The only exception is near the Windward Passage, where fresh trades are analyzed. Seas are 4-7 ft throughout the basin, except in the W Atlantic north of 27N and west of 65W where seas are 2-4 ft. For the forecast, fresh to strong E winds will pulse in the afternoons and evenings north of Hispaniola for the next several days. Moderate to fresh trades will prevail elsewhere south of 22N. Surface ridging associated with the Bermuda High will slowly sink southward to 27N by midweek, leading toward quiescent conditions across the remainder of the western Atlantic. $$ Mahoney