000 AXNT20 KNHC 231021 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Mon Aug 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 1000 UTC. ...SPECIAL FEATURES... At 23/0300 UTC, the last advisory was issued by the National Hurricane Center on Henri. At 23/0900 UTC, Tropical Depression Henri is centered near 41.6N 74.4W or 50 nm NNW of New York City moving E at 1 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 25 kt with gusts to 35 kt. Henri is expected to produce additional rainfall of 1 to 3 inches, with locally higher amounts possible, over portions of Long Island, New England, southeast New York, New Jersey, and eastern Pennsylvania through today. Heavy rainfall from Henri will continue to result in limited to considerable flash, urban, and small stream flooding impacts, along with minor to isolated moderate river flooding. Swells are expected to continue across much of the east coast of the U.S. and Atlantic Canada through today. These swells could cause life-threatening surf and rip current conditions. For the latest rainfall reports and wind gusts associated with Tropical Depression Henri see the following link: https://www.wpc.ncep.noaa.gov/discussions/nfdscc3.html ...TROPICAL WAVES... A tropical wave is along 20W, from 19N southward. The wave is moving W at 10 to 15 knots. Scattered moderate convection is ahead of the wave axis from 05N-08N between 20W-23W. A well defined tropical wave is along 35W, from 20N southward. The wave is moving W at 10 knots. A 1011 mb low pressure is analyzed along the wave axis near 13N. Disorganized shower activity is associated with this low. Little, if any, development is expected to occur during the next couple of days. Some gradual development, however, is possible by the middle to latter part of the week as the system moves northwestward at 10 to 15 mph over the central Atlantic. The latest Tropical Weather Outlook gives this system a low chance of tropical cyclone formation through 5 days. Recent satellite derived wind data provided observations of fresh to strong winds on the E side of the low center. A weak tropical wave is along 50W, from 20N southward. The wave is moving W 10 to 15 knots. Convection is limited near the wave axis. An active tropical wave is moving across the eastern Caribbean. Its axis is along 63W and extends from the northern Leeward Islands into eastern Venezuela. The wave is producing scattered showers and thunderstorms, particularly from 10N-15N between 55W- 68W. This convective activity is affecting the Windward Islands and regional waters. The wave is also enhancing scattered showers and thunderstorms over eastern Venezuela. Fresh to strong NE winds are noted per scatterometer data ahead of the wave axis. The wave will reach the Mona Passage tonight, but the associated moisture is forecast to remain well south of Puerto Rico. A second tropical wave is over the Caribbean Sea along 80W from 20N southward, moving westward 10 to 15 knots. Scattered moderate convection is near the southern end of the wave axis from 10N-13N between 78W-82W. Similar convection is across eastern plains of Nicaragua. Another tropical wave is over the Yucatan peninsula crossing near the Belize/Guatemala border into El Salvador. The wave is helping to induce convection over parts of Belize, Guatemala and El Salvador. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Mauritania near 17N16W to a 1011 mb low pressure located near 13N35W to 08N52W. Most of the convective activity across the area is associated with the aforementioned tropical waves. ...GULF OF MEXICO... High pressure dominates the Gulf waters producing mainly gentle to moderate winds. Seas are generally below 4 ft based on recent altimeter pass. A 1017 mb high pressure center is noted over the NE Gulf near 27N87W. Small area of showers and thunderstorms is over the Bay of Campeche near 20N94W. High pressure will remain in control of the weather pattern across the Gulf waters through Fri. Fresh to possibly locally strong winds will pulse west of the Yucatan Peninsula tonight and again Tue night due to local effects associated with a thermal trough. Looking ahead, marine conditions may deteriorate over the SW Gulf during the upcoming weekend as a tropical system move across the region. ...CARIBBEAN SEA... Two tropical waves are moving westward across the Caribbean Sea. Please, see the Tropical Waves section for details. The most recent scatterometer data show fresh to strong winds across the central Caribbean, and in the Gulf of Honduras with seas to 8 ft near the coast of Colombia. Convection across the basin are related to the tropical waves. The aerial extent of the trade winds will increase over the next 24 hours covering most of the waters S of 17N and E of 80W. As a result, fresh to strong trade winds are expected over the east and central Caribbean through midweek, with building seas of 8 to 10 ft. Fresh to locally strong winds and seas to 8 ft are also expected in the Windward passage through Tue night. ...ATLANTIC OCEAN... Tree tropical waves are moving westward between the W coast of Africa and the Lesser Antilles. Please, see the Tropical Waves section for details. High pressure of 1022 mb is located just E of Bermuda near 32N62W. Another 1022 mb high pressure is centered about midway between the Azores and the Madeira Islands. These systems dominate the Atlantic forecast waters where gentle to moderate winds are noted. Fresh to locally strong winds area between the W coast of Africa and the Canary Islands as well as from 18N-26N E of 21W to the coast of Africa. The northern extent of the tropical wave located near 35W is forecast to break-up and move northwestward as a trough across the Atlantic waters. An area of fresh to strong E-SE winds will follow the trough allowing seas to build to 10-12 ft. This trough is forecast to approach the SW N Atlantic by Thu. For the forecast W of 65W: High pressure located near Bermuda will dominate the forecast region through at least Wed. A surface trough is forecast to approach from the E on Thu, possible reaching the NE waters on Fri. Fresh to locally strong winds are expected N of Hispaniola including the approaches to the Windward Passage through Tue night. The pressure gradient could increase some across the SW N Atlantic Tue night into Wed between high pressure located just N of Bermuda and the approaching surface trough. $$ GR