000 AXNT20 KNHC 142146 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Thu Jul 15 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 2110 UTC. ...TROPICAL WAVES... A tropical wave is in the Atlantic Ocean near 34W/35W from 15N southward, moving W at around 15 to 20 kt. Scattered moderate convection is noted from 08N to 09N between 35W and 37W. The northern portion of the wave is surrounded by SAL. A tropical wave is in the Atlantic Ocean near 57W from 15N southward to across Suriname, moving W at around 15 kt. Scattered moderate convection is noted from 10N to 15N between 55W and 58W, and from 07N to 12N between 52W and 55W. A tropical wave is over the Yucatan Peninsula near 91W from 22N southward, moving W at around 10 to 15 kt. Scattered moderate convection is noted across portions of the Yucatan Peninsula. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean from Guinea-Bissau near 11.5N15W to 09N33W. The ITCZ continues from 08N36W to 07N54W. Scattered moderate convection is noted from 07N to 10N between 14W and 18W, from 05N to 11N between 22W and 32W, and from 02N to 07N between 36W and 39W. GULF OF MEXICO... A southeastern U.S.A. ridge extends across most of the lower Mississippi Valley. Gentle to moderate E-SE flow prevails across the basin, locally moderate to fresh just north of the northern Yucatan Peninsula coast. Seas are mainly in the 2 to 4 ft range across the basin. Scattered moderate convection is noted in the SW Gulf from 18N to 23N between 92W and 97W. Isolated to scattered showers and thunderstorms are noted across the waters north of 26N and west of 87W, as well as across the western Florida Peninsula extending into the Florida Gulf coastal waters. For the forecast, a surface high pressure ridge over the SE United States will maintain gentle to moderate E to SE winds and slight to moderate seas across much of the Gulf through Fri. A surface trough will develop each day over the Yucatan and shift westward into the SW Gulf. This will support fresh to occasionally strong winds off the northwest Yucatan Peninsula and eastern Bay of Campeche during the overnight hours through Thu night. Looking ahead, the northern end of a tropical wave will move through the southeast Gulf Fri and across the central Gulf Sat and Sun, bringing a slight increase in winds and seas to the Straits of Florida Fri night into Sat. CARIBBEAN SEA... Please refer to the Tropical Waves section for details on a tropical wave over the Yucatan Peninsula. An upper level trough extends from the Atlantic Ocean, across the Greater Antilles, into the southern Caribbean Sea. Dry, subsident northerly flow aloft is suppressing showers and thunderstorms across much of the central and western Caribbean Sea. Scattered showers and isolated thunderstorms are within 60 nm of the coasts of Panama and Costa Rica, as well as across Hispaniola and northern South America. Fresh to strong trade winds are noted in the south-central Caribbean and in the vicinity of the Gulf of Honduras. Moderate trades prevail elsewhere, locally fresh across the Windward Passage, and except gentle to moderate in the SW Caribbean south of 10N. Seas are mainly in the 4 to 6 ft range across the basin, except 7 to 11 ft from 10N to 15N between 74W and 82W due to the stronger winds. For the forecast, high pressure north of the region will continue to support fresh to strong tradewinds and rough seas over the south-central Caribbean. Fresh to strong NE to E winds are expected in the Gulf of Honduras through tonight. Winds and seas will diminish Thu and Fri as the high pressure weakens, although areas of fresh to strong winds will continue to pulse in the Gulf of Venezuela and near the coast of NE Colombia. Looking ahead, tradewinds and related seas will increase over the south-central Caribbean and slightly around the Leeward Islands Sat into Sun as another tropical wave reaches the eastern Caribbean. ATLANTIC OCEAN... Please refer to the Tropical Waves section for details on two tropical waves in the Atlantic Ocean. Gentle to moderate anticyclonic wind flow covers most of the Atlantic basin. Fresh to strong N-NE winds are occurring from 18N to 31N west of the coast of Africa to 30W due to a locally tight pressure gradient. A pair of surface high pressure centers are in the central Atlantic just north of the area, 1026 mb near 34N51W and 1025 mb near 33N46W. Seas of 3 to 6 ft dominate the waters west of 30W, except around 3 ft just south of the high pressure centers. Seas are 6 to 9 ft near the fresh to strong winds off the coast of Africa. A large upper level trough is just to the north of Puerto Rico. A weak surface trough is located from 30N59W to 24N62W. A few showers and thunderstorms are noted within 60 nm to the west of the trough. A 1026 mb high pressure center is just north of the area near 33N74W. For the forecast for the waters west of 65W, a high pressure ridge just north of the area, off the Carolina and Georgia coasts, will maintain gentle to moderate E winds across the western Atlantic. Looking ahead, winds and seas will build slightly Sat south of 22N and north of the Leeward Islands as a tropical wave approaches the region from the east. Expect fresh to strong winds to pulse off Hispaniola Sat through Mon. $$ Lewitsky