000 AXNT20 KNHC 081806 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Fri Oct 8 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 1705 UTC. ...SPECIAL FEATURES... An elongated area of low pressure located more than 200 miles off the coast of South Carolina is producing disorganized showers and thunderstorms well to the east of its center of circulation. Satellite images and surface observations indicate that the low pressure system located a couple of hundred miles east of the coast of South Carolina is gradually becoming better defined. Although the associated shower and thunderstorm activity is currently disorganized, environmental conditions could briefly become marginally conducive for the low to acquire subtropical characteristics by Saturday night and early Sunday. By early next week, the low is expected to interact with a frontal boundary, which should end the opportunity for any subtropical or tropical formation. The low is forecast to meander offshore the Carolinas today, and then slowly move back toward the west-northwest and northwest on Saturday, bringing the system closer to the coast of North Carolina. The disturbance has a medium chance of development over the next 48 hours. Please read the latest Tropical Weather Outlook at hurricanes.gov and the High Seas Forecast from the Ocean Prediction Center at ocean.weather.gov ...TROPICAL WAVES... An Atlantic tropical wave has its axis along 38W, south of 16N, and it is moving W at 15 to 20 kt. Deep convection near the southern portion of this wave is mainly associated with the nearby ITCZ. The northern portion is devoid of deep convection due to dry Saharan air. A Caribbean tropical wave has its axis along 67W, south of 19N, extending from Puerto Rico to Venezuela, and it is moving W at 15 to 20 kt. Scattered moderate to isolated strong convection is noted from 12N to 16N and between 64W and 71W. ...MONSOON TROUGH/ITCZ... The monsoon trough remains over Africa while the ITCZ extends westward from the Sierra Leone coastline at 09N13W to 07N25W and to 06N38W. The ITCZ then continues from 06N39W to 02N50W. Scattered moderate to isolated strong convection is occurring within 300 nm on both sides of the ITCZ between 13W and 48W. ...GULF OF MEXICO... The previously stationary front in the NE Gulf of Mexico is now on the move as a cold front, extending from a 1017 mb low pressure in SW Georgia to 28N87W. A pre-front trough is analyzed from the Big Bend area of Florida to 27N88W and a few showers and isolated thunderstorms is noted within 100 nm to the E of the trough axis. Another surface trough is present in the SW Gulf of Mexico, extending from 24N92W to 18N95W. Scattered moderate convection is seen on satellite imagery S of 24N and between 92W and 96W. Dry continental air continues to percolate into the NW Gulf, allowing for tranquil weather conditions. A weak pressure gradient dominates most of the basin, resulting in gentle to moderate cyclonic winds. However, fresh to locally strong NW winds are occurring within 60 nm of the coast of Veracruz, especially from 19N to 21N. Seas of 3-5 ft are present in the Bay of Campeche and SE Gulf, while 1-3 ft are prevalent elsewhere. For the forecast, the frontal boundary and surface troughs continue to support scattered showers and tstms over the NE and SW Gulf. The pressure gradient between high pressure along Mexico and the trough in the Bay of Campeche continue to support fresh to strong northerly winds over the Veracruz adjacent waters, forecast to diminish to moderate winds early this evening. Weak high pressure will build across the E half of the basin this upcoming weekend into early next week, and support moderate to locally fresh return flow W of 90W Sun through Tue night. ...CARIBBEAN SEA... The E Pacific monsoon trough enters the SW Caribbean Sea through the coast of Costa Rica and extends to NW Colombia. Scattered moderate convection is noted within 60 m of the coasts of Nicaragua, Costa Rica, Panama and NW Colombia. Outside of the active tropical wave mentioned in the Tropical Waves section, the rest of the Caribbean enjoys fairly tranquil weather conditions. Recent scatterometer satellite data show fresh to strong trades in the south-central Caribbean, with the strongest winds occurring within 60 nm of the coast of Colombia. Gentle to moderate trades prevail elsewhere in the basin. Seas of 5-8 ft are occurring in the central and SW Caribbean, with the highest seas off the coast of NW Colombia. Seas of 3-6 ft are prevalent elsewhere. For the forecast, moderate to locally fresh trades are expected across the eastern half of the Caribbean and the tropical Atlantic waters through the forecast period as surface riging builds NE of the area and both a tropical wave and a low level disturbance moves across the area over the weekend. The tropical wave near 67W is forecast to move over the central basin tonight and Sat and across the W Caribbean on Sun. The low level disturbance is forecast to move across the Lesser Antilles Sat evening with active weather extending to Puerto Rico and the Virgin Islands Sun evening through Tue night. The disturbance is forecast to be over the Central Caribbean Wed morning, affecting Hispaniola and adjacent waters. ...ATLANTIC OCEAN... A 1025 mb subtropical ridge is centered near the Azores. A surface trough extends from 27N58W to Hispaniola and it is producing a few showers and isolated thunderstorms nears the trough axis. Another surface trough associated with the remnants of an old frontal boundary extends from 26N42W to 30N51W. Scattered moderate convection is noted from 25N to 31N and between 40W and 55W. Recent scatterometer satellite data indicate that fresh to locally strong winds are found near the strongest convection. A third surface trough extends from 16N53W to 10N56W and it is generating widespread showers and isolated thunderstorms, mainly from 09N to 14N and between 52W and the Lesser Antilles. Satellite-derived wind data depict fresh to locally strong trades S of 22S and between 40W to the Lesser Antilles. Fresh to locally strong N-NE winds are also occurring from 18N to 28N and E of 25W, including the waters surrounding the Canary Islands. Moderate or weaker winds are prevalent elsewhere in the tropical Atlantic. Seas of 3-6 ft prevail W of 60W, while 7-10 ft are present S of 20N and between 40W and the Lesser Antilles. Seas of 5-8 ft are found elsewhere. The Cumbre Vieja volcano, that is on the island of La Palma in the Canary Islands, has been erupting since 19 September at 1410 UTC. An ash plume is partially identifiable on satellite imagery drifting westward toward the Tenerife Island. Top is estimated with Webcams at 11,000 ft. 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/. The next advisory will be issued no later than 08/2100 UTC. For the forecast W of 65W, an elongated area of low pressure located more than 130 nmi off the coast of South Carolina continue to support scattered showers and tstms across the offshore waters N of the Bahamas. By Sunday, environmental conditions could briefly become marginally conducive for some subtropical development of the low. However, by early next week, the low is expected to interact with a frontal boundary, which should hinder the opportunity for any subtropical or tropical formation. Regardless of development, the low will continue to support active weather over the northern offshore waters today, with this activity extending across the Bahamas during the remaining weekend. $$ DELGADO