885 AXNT20 KNHC 051724 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sun Sep 5 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 1700 UTC. ...SPECIAL FEATURES... Category Three Hurricane Larry is centered near 19.5N 49.7W at 05/1500 UTC or 760 nm E of the Northern Leeward Islands moving NW at 11 kt. Estimated minimum central pressure is 955 mb. Maximum sustained wind speed is 110 kt with gusts to 135 kt. The eye diameter is 45 nm on IR satellite imagery. Numerous moderate to strong convection is noted within about 150 nm of center. Seas of 12 ft or higher extend within 300 nm in the N semicircle and 240 nm in the S semicircle, with seas as high as 46 ft. On the forecast track, a northwestward motion with a slight decrease in forward speed is expected during the next few days. Little change in strength is forecast during the next few days, although fluctuations in intensity will be possible. Larry is a large hurricane, and is expected to remain a major hurricane through the middle of this week. Swells generated by Larry are expected to reach the Lesser Antilles today, and will spread westward to portions of the Greater Antilles, the Bahamas, and Bermuda on Monday and Tuesday. Significant swells will likely reach the east coast of the United States and Atlantic Canada by midweek. These swells are likely to cause life-threatening surf and rip current conditions. Based on an altimeter pass, seas of 8-9 are noted from 12N-20N near 55W. Please read the latest High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... An east Atlantic tropical wave has an axis along 19W/20W from 03N to 19N, moving W around 5-10 kt. Scattered moderate convection is noted from 10N to 14N between 17W and 20W. An Atlantic Ocean tropical wave has an axis along 36W/37W from 03N to 16N, moving W at 5-10 kt. The wave is situated at the leading edge of a Saharan dust plume. As a result, no significant convection is noted with the wave at this time. A Caribbean Sea tropical wave has an axis along 76W, stretching from eastern Cuba to NW Colombia, moving W at 10 kt. The wave is likely enhancing scattered moderate convection over northern Colombia and NW Venezuela. Fresh to locally strong E winds are occurring E of the wave axis in the south-central Caribbean. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic ocean near the Mauritania/ Senegal border at 16N16W to 07N28W. The ITCZ extends from 07N28W to 04N40W, then continues W of a tropical wave from 04N38W to the coast of Guyana and Venezuela near 08N60W. Aside from the convection mentioned in the Tropical Waves section above, scattered moderate convection is observed from 06N-08N between 20W-26W, and from 04N-08N between 42W and 46W. GULF OF MEXICO... Disorganized showers and thunderstorms over portions of Central America and the Yucatan Peninsula are associated with a surface trough and an upper-level disturbance. A 1011 mb low pressure is analyzed near 19N91W at 1200 UTC. Locally heavy rains are likely to continue today over that area in association with this system, forecast to move northwestward over the southwestern Gulf of Mexico later today, then move slowly northward or northeastward over the western or central Gulf of Mexico. Upper-level winds are only expected to be marginally conducive for tropical cyclone formation, but some slow development is possible while the system moves across the Gulf of Mexico through the middle of the week. The latest Tropical Weather Outlook states that this system has a low chance of tropical cyclone formation through 5 days. For more information please see hurricanes.gov Elsewhere in the Gulf of Mexico, a stationary front persists over the NE Gulf, extending from northern Florida to near Mobile, Alabama. Isolated showers are near the frontal boundary. A pair of 1015 mb high pressure centers are located near 26N92W and 24N84W, and are the dominant weather features in the Gulf of Mexico this morning. A diffluent pattern aloft supports scattered showers and thunderstorms over the NE Yucatan peninsula and adjacent waters, including Cozumel and Cancun. Light to gentle winds and slight seas encompass the basin, except NW of the Yucatan peninsula where gentle to moderate E-SE winds are occurring. These winds are likely related to a thermal trough that usually develops over the Yucatan peninsula during the night hours, and moves across the Bay of Campeche during the morning hours. For the forecast, the stationary front over the northeast Gulf will dissipate today, while a ridge will dominate much of the Gulf region producing mainly light to gentle winds. CARIBBEAN SEA... See the Tropical Waves section above for details on a tropical wave in the central Caribbean. Recent scatterometer data provide observations of fresh to locally strong trades over the south-central Caribbean, and moderate to fresh winds elsewhere, except light to gentle winds in the lee of Cuba, and in the SW Caribbean south of 10N-11N. Seas are 4-7 ft S of 18N E of 80W, and 3-5 ft S of 18N W of 80W, including the Gulf of Honduras. Seas of 1-3 ft dominates the NW Caribbean. An upper-level extending from Hispaniola to eastern Panama is helping to induce scattered showers with embedded thunderstorms over the south-central Caribbean, mainly S of 15N between 70W-81W. Similar convective activity is noted over the Gulf of Honduras and the NW Caribbean under a diffluent pattern aloft. For the forecast, Hurricane Larry will remain well to the northeast of the Leeward Islands through Mon, then move farther north of the area through mid week. For more information, please refer to the Special Features section above. Elsewhere, gentle to moderate trade winds will persist, pulsing to fresh winds off Colombia mainly at night. ATLANTIC OCEAN... Attention remains focused of Major Hurricane Larry. Please, see the Special Features section for details. Larry is forecast to approach Bermuda during the next several days, likely as a major hurricane, bringing a risk of strong winds, heavy rainfall, and coastal flooding to the island by the middle of this week. While it is too soon to determine the magnitude of these hazards and potential impacts on Bermuda, interests there should closely monitor the latest forecast updates during the next several days. A weak stationary front enters the forecast area near 31N70W, then continues SW over northern Florida into the NE Gulf of Mexico. Isolated showers and light winds are near the frontal boundary. Otherwise, high pressure dominates most of the Atlantic forecast waters, outside of the influence of Hurricane Larry. This is leading to gentle to moderate winds across the basin. Farther to the east, a belt of moderate to fresh trades is noted roughly from 13N-20N E of 38W, and just N of the Cabo Verde Island to the W coast of Africa. A cold front crosses between Madeira and the Azores islands and extends along 30N23W to 29N30W to beyond 31N35W. A broken band of mainly low clouds with isolated showers is related to the front. For the forecast, hurricane Larry Larry will move to 20.5N 51.1W this evening, 21.9N 52.7W Mon morning, 23.0N 54.0W Mon evening, 24.3N 55.4W Tue morning, 25.7N 56.7W Tue evening, and 27.3N 58.1W Wed morning. $$ GR