000 AXNT20 KNHC 091017 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Sat Oct 9 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... An area of low pressure located about 200 miles south-southeast of Cape Hatteras, North Carolina, continues to produce disorganized showers and thunderstorms. Environmental conditions could briefly become marginally conducive for the low to acquire subtropical characteristics 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 near the North Carolina coast. Regardless of development, intermittent periods of locally heavy rains and gusty winds will affect eastern portions of North Carolina during the next day or two. An Air Force Reserve reconnaissance aircraft is scheduled to investigate the system this afternoon, if necessary. There is a medium chance of development for this low over the next 48 hours. Interests along the Carolina coast should monitor this system closely and 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... An Atlantic tropical wave is near 44W from 16N southward, moving W at 15 to 20 kt. Scattered moderate convection is where the wave meets the ITCZ from 06N to 09N between 41W and 47W. A second tropical wave is E of the Lesser Antilles along 55W/56W from 18N southwestward, moving W near 10 kt. A cluster of moderate to isolated strong convection is along the wave axis covering the waters from 11N to 14N between 54W and 57W. The wave will bring showery and windy conditions to the Windward Islands later today, then the Leeward Islands tonight; and the US/UK Virgin Islands and Puerto Rico late on Sun. It might reach Hispaniola on Mon. A Caribbean tropical wave is near 71W and extends from Dominican Republic southward across western Venezuela, moving W near 15 kt. Convection is limited along the wave axis, with the exception of moderate to isolated strong convection over Lake Maracaibo. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic Ocean through the coast of Senegal near 15N17W, then continues SW to near 07N25W. The ITCZ extends from 07N25W to 08N38W to 06N49W. Scattered moderate to isolated strong convection is found from 07N to 11N between 20W and 30W, and from 03N to 10N between 30W and 40W. ...GULF OF MEXICO... A frontal trough extends from Ft. Myers, Florida to near 22N90W. Scattered showers and thunderstorms are along the frontal trough affecting South Florida and the SE Gulf waters. The remainder of the Gulf is under the influence of a ridge. A cluster of moderate to strong convection is over the eastern Bay of Campeche, just ahead of a surface trough extending over the Yucatan Peninsula. Recent satellite derived wind data show mainly gentle to moderate winds across the basin, with the exception of moderate to fresh northerly winds over the Bay of Campeche. Seas are generally in the 1 to 3 ft range. For the forecast, the above mentioned frontal trough will move slowly across South Florida and the Florida Keys this weekend helping to induce scattered to numerous showers and thunderstorms. Moderate to fresh southerly return flow is expected over the western Gulf late Sun through Wed night under the influence of a ridge. ...CARIBBEAN SEA... A tropical wave is currently located E of the Lesser Antilles producing active weather and fresh to strong winds. Refer to the Tropical Waves section for more information. Otherwise, gentle to moderate trade winds prevail, with the exception of light to gentle winds over the NW Caribbean. Seas are 3 to 5 ft across most of the waters S of 18N E of 83W, and 1 to 3 ft over the NW Caribbean. Seas of 7-9 ft are noted in association with the tropical wave. For the forecast, the tropical wave currently located E of the Lesser Antilles along 55W/56W will bring showery and windy conditions to the Windward Islands later today, then the Leeward Islands tonight; and the US/UK Virgin Islands and Puerto Rico late on Sun. It might reach Hispaniola on Mon. Seas of 7-9 ft will follow the wave axis over the Atlantic waters through early Mon. ...ATLANTIC OCEAN... An area of low pressure remains N of area about 200 miles south- southeast of Cape Hatteras, North Carolina. Please, see the Special Features section for more details. A surface trough extending from the low center to central Florida is producing scattered to numerous showers and thunderstorms. This convective activity will spread across South Florida and the NW Bahamas today and Sun. Weak surface troughing is causing scattered showers and isolated thunderstorms across the west-central Atlantic from 25N to 31N between 40W and 65W. The trough extends from 31N43W to 29N50W to 28N60W. Moderate to fresh SW to W winds are noted just S of the trough between 45W and 50W while mainly light to gentle winds prevail elsewhere near the trough axis. The remainder of the Atlantic forecast waters is under the influence of a ridge anchored on a 1029 mb high pressure located over the Azores. The pressure gradient between the ridge and lower pressures over W Africa is resulting in an area of fresh to strong NE winds from 20N to 25N E of 26W to the coast of Western Sahara. A northerly swell event will begin to propagate across the central Atlantic waters by Sun evening, building seas to 8 to 11 ft N of a line from 31N38W to 28N50W to 31N62W by early Mon morning. This swell event will cover most of the waters N of 24N E of 60W by Mon evening. 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/. $$ GR