000 AXNT20 KNHC 092143 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Sun Oct 10 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 2200 UTC. ...SPECIAL FEATURES... Satellite-derived wind data and surface observations indicate that a large, non-tropical low pressure system located about 150 miles southeast of Morehead City and Wilmington, North Carolina, is producing a broad area of gale-force winds to the west and north of the center. Associated shower and thunderstorm activity has been gradually increasing and becoming better organized today, and the low could acquire subtropical characteristics late this afternoon through early Sunday. However, by late Sunday and Monday, environmental conditions should become unfavorable for any further development. The low is forecast to move slowly northwestward during the next day or so, and approach the North Carolina coast tonight and early Sunday. Therefore, interests along the North Carolina coast should monitor the progress of this system. Regardless of development, intermittent periods of locally heavy rains and gusty winds will affect southeastern and eastern portions of North Carolina during the next day or two. There is a medium chance of development for this low over the next 48 hours. For more details, please read the latest Tropical Weather Outlook at https://www.hurricanes.gov and Mariners can read the latest High Seas Forecast from the Ocean Prediction Center at https://ocean.weather.gov for more information. ...TROPICAL WAVES... The axis of a tropical wave is near 45W, south of 18N, moving W at 15 to 20 kt. Scattered moderate to isolated strong convection is observed from 05N to 10N and between 44W and 50W. The axis of a tropical wave is near 59W, south of 20N, moving W near 15 kt. Scattered moderate isolated strong convection is noted from 12N to 19N between 55W and 61W. The axis of a tropical wave is near 73W, south of 20N, moving W at 15 to 20 kt. There is no deep convection associated with this wave. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean through the coast of Mauritania near 17N16W and continues SW to near 08N22W. The ITCZ continues from 08N22W to 09N44W. Aside from convection noted in the tropical waves section above, scattered moderate to isolated strong convection is noted from 07N to 10N between 20W and 30W, and from 04N to 12N between 35W and 44W. ...GULF OF MEXICO... A surface trough extends off the coast of southern Florida to near 25N85W. A second surface trough is found over the far SW Gulf. Otherwise, high pressure prevails across the Gulf waters. Light to gentle winds, and seas of 1-3 ft, prevail across the Gulf waters. For the forecast, a weak pressure gradient support light to gentle variable winds with seas to 3 ft. A weak surface ridge will start to build across the basin this evening and moderate to locally fresh return flow will develop over the western half of the basin, continuing through Thu night. ...CARIBBEAN SEA... A weak pressure gradient prevails across the area. Moderate to fresh winds are over the eastern and central Caribbean. Light to gentle winds prevail over the western Caribbean. Seas are in the 3-5 ft range over the eastern and central Caribbean, and 1-3 ft over the western Caribbean. For the forecast, a tropical wave with axis will provide fresh winds and scattered showers to the Lesser Antilles through Monday. Shower activity associated with this wave will affect the US/UK Virgin Islands and Puerto Rico Sun evening through Tue and Hispaniola from Mon through Wed night. Seas to 8 ft will impact the Atlantic waters E of the Lesser Antilles through Sun evening. Otherwise, moderate to fresh winds in the eastern half of the Caribbean will diminish to gentle to moderate early on Tue and to light to gentle on Thu. ...ATLANTIC OCEAN... A surface trough extends from 31N78W to central Florida. Scattered moderate and isolated strong convection is noted within 120 nm east of the trough axis. A second trough extends from 31N41W to 28N47W. Scattered moderate convection is noted within 60 nm east of the trough. A third trough is noted from 27N53W to 25N69W. Scattered moderate convection is noted within 60 nm of the trough axis. Moderate to fresh trade-winds prevail over the tropical waters south of 20N. Light to gentle winds are noted over the tropical and subtropical waters north of 20N. Seas are in the 5-8 ft range south of 20N, and 3-6 ft over the open waters north of 20N. Seas of 1-3 ft prevail west of the Bahamas. The Cumbre Vieja volcano, that is on the island of La Palma in the Canary Islands, has been erupting since 19 September 2021. Currently, volcanic ash is not easily detectable due to cloud cover. Marine and aviation interests should monitor this on- going situation, by reading the Volcanic Ash Advisory, that is issued by Meteo-France, at http://vaac.meteo.fr/volcanoes/la- palma/. For the forecast W of 65W, A surface trough across the NW waters will continue to produce showers and tstms across the Bahamas and offshore zones W of 70W through Mon. $$ AL