000 AXNT20 KNHC 112329 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Tue Sep 12 2023 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 2300 UTC. ...SPECIAL FEATURES... Major Hurricane Lee is centered near 23.6N 64.2W at 11/2100 UTC or 330 nm N of the Northern Leeward Islands, moving WNW at 6 kt. Estimated minimum central pressure is 948 mb. Maximum sustained wind speed is 100 kt with gusts to 120 kt. Lee continues to exhibit a double eyewall structure as reported by the Air Force Hurricane Hunters and seen in recent microwave images. Numerous moderate to strong convection is noted within 120 nm N and 150 nm S semicircles of the center of Lee. Seas in excess of 12 ft reach as far as 330 nm in the northern semicircle, and 270 nm in the SE quadrant and 300 nm in the SW quadrant with maximum seas of 48 ft. On the forecast track, Lee is expected to pass near, but to the west, of Bermuda in a few days. Lee is a category 3 hurricane on the Saffir- Simpson Hurricane Wind Scale. Little change in strength is forecast during the next couple of days. Swells generated by Lee are affecting portions of the Lesser Antilles, the British and U.S. Virgin Islands, Puerto Rico, Hispaniola, the Turks and Caicos Islands, the Bahamas, and Bermuda. These swells are likely to cause life-threatening surf and rip current conditions. Dangerous surf and rip currents have begun to affect portions of the southeastern U.S. coast, and these conditions are forecast to spread northward along much of the U.S. East Coast during the next day or two. Please consult products from your local weather office. Margot becomes the fifth hurricane of the 2023 Atlantic Hurricane Season. At 11/2100 UTC, Hurricane Margot is centered near 27.0N 39.8W or 1100 nm NW of the Cabo Verde Islands, moving N at 10 kt. Estimated minimum central pressure is 988 mb. Maximum sustained wind speed is 65 kt with gusts to 80 kt. Scattered moderate to isolated strong convection is evident within 90 nm of the center of Margot. Seas in excess of 12 ft reach as far as 210 nm of the center, except 150 nm SW quadrant with maximum seas of 22 ft. Margot is moving toward the north, and this motion is expected to continue for the next several days. Further strengthening is forecast during the next 48 hours. 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 on Lee and Margot at www.hurricanes.gov for more details. ...TROPICAL WAVES... A tropical wave (AL98) located over the far eastern tropical Atlantic between the Cabo Verde Islands and the west coast of Africa is producing disorganized showers and thunderstorms. Its axis is along 21W/22W S of 18N. Environmental conditions appear conducive for gradual development of this system, and a tropical depression could form by the weekend while it moves westward to west-northwestward at 15 to 20 kt over the central tropical Atlantic. Currently, this system has a low chance of tropical cyclone formation through 48 hours, and a medium chance through 7 days. A weak area of low pressure (AL97) located several hundred miles west-southwest of the Cabo Verde Islands is producing disorganized shower and thunderstorm activity. This low is along a tropical wave with axis along 32W and S of 18N. Development of this system is unlikely before it merges with the tropical wave (AL98) incoming from the east during the next couple of days. As a result, there is a low chance of tropical cyclone formation during the next 7 days. Refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details on AL97 and AL98. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean through the coast of Mauritania near 18N16W, then continues southwestward to a 1012 mb low pressure (AL97) near 12.5N32W to 14N50W. The ITCZ extends from 09N52W to 10N61W. Scattered moderate convection is noted from 08N to 16N between 22W and 30W, and within about 100 nm W of the weak area of low pressure (AL97). ...GULF OF MEXICO... A surface trough reaches from off the mouth of the Mississippi River in the north-central Gulf to near 24N94W. A weak 1014 mb low pressure is along the trough axis near 27N92W. Farther east, a weak ridge extends from the western Atlantic into the northeastern Gulf. This pattern is supporting only light to gentle winds and slight seas across the basin. A band-like of scattered showers and thunderstorms is evident across the NE and central Gulf, affecting mainly the waters N of 26N E of 87W, and from 22N to 27N between 87W and 92W. For the forecast, a weak ridge will dominate the Gulf waters throughout the forecast period supporting light to gentle winds. Scattered thunderstorms can be expected across the western Yucatan and eastern Bay of Campeche each late afternoon and evening. ...CARIBBEAN SEA... Please read the Special Features section about large swell generated by Major Hurricane Lee impacting the northeast Caribbean islands. An area of showers, with embedded thunderstorms is over the NW Caribbean and western Cuba, including the Isle of Youth. A surface trough is analyzed from central Cuba to near 14N82W. A diffluent pattern aloft is helping to induce this convective activity. scattered showers and thunderstorms are also noted over parts of eastern Cuba and Jamaica. The subtropical ridge that is normally present north of the basin is being disrupted in part by Hurricane Lee. This pattern is supporting gentle to moderate winds. Seas of 7 to 9 ft generated by Major Hurricane Lee are propagating across the NE Caribbean passages E of La Mona Passage. Seas of 6-8 ft are likely between the northern Leeward Islands and St. Croix. Elsewhere 3-4 ft seas prevail, except 1-3 ft in the NW Caribbean, higher near thunderstorms. For the forecast, moderate to locally fresh trade winds will continue in the central and eastern Caribbean through this evening before Lee in the Atlantic disrupts the pressure pattern. The large easterly swell across the adjacent Atlantic will gradually become NE and then N today through Thu, and move through the Caribbean Passages and into the Caribbean waters between the Leeward Islands and the Mona Passage. Seas across these Caribbean Passages and waters will diminish significantly Thu night through Fri. ...ATLANTIC OCEAN... Please see the Special Features section for information about Hurricane Lee and Hurricane Margot. Outside of the weather conditions associated with the tropical waves and tropical cyclones, no significant convection is noted across the basin. Weak low pressure near 14.5N48W is producing a few showers. The most recent scatterometer satellite pass indicated the cyclonic circulation related to this weak low with mainly gentle to moderate winds around it, and only 5 to 10 kt near the center. The scatterometer passes also revealed a band of moderate E to SE winds over the eastern Atlantic from the coast of Western Sahara toward Hurricane Margot. A weak 1019 high pressure is near 29N27W. Gentle winds are noted elsewhere across the Atlantic outside of the areas near Lee and Margot, with combined seas of 4 to 6 ft in mixed swell. For the forecast west of 55W, Hurricane Lee is expected to maintain a slow NW motion and strengthen modestly through Tue, then begin a gradual turn toward the N on Wed. Lee will move to 24.0N 65.1W Tue morning, 24.6N 66.1W Tue afternoon, 25.3N 66.9W Wed morning, 26.5N 67.5W Wed afternoon, 28.3N 67.8W Thu morning, and 30.3N 67.9W Thu afternoon. Lee will change little in intensity as it moves N of the area Fri afternoon. Large E to SE swell dominating the waters east of 78W will continue to propagate westward across the Atlantic, reaching the Florida coast Tue afternoon. Large swell from Lee will dominate regional waters Tue night through Fri. $$ GR