000 AXNT20 KNHC 041808 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Mon Oct 4 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 1630 UTC. ...SPECIAL FEATURES... The center of Hurricane Sam is near 42.6N 45.7W at 04/1500Z or about 400 miles SE of Cape Race, Newfoundland and moving NE or 45 degrees at 28 knots. The estimated minimum central pressure is 960 mb. The maximum sustained winds are 85 knots with gusts to 105 knots. Seas are peaking at 48 to 50 ft near and up to 330 nm NW of the center. Numerous moderate to strong convection is noted up to 105 nm in a NW semicircle, scattered moderate convection is up to 65 nm in a SE semicircle. This general motion is expected to continue through tonight, then turn toward the ENE with a decrease in forward speed by Tuesday. A gradual weakening trend will continue through Tue evening as Sam transitions into a powerful post-tropical storm over the N central Atlantic. Large swell continues to be generated by Sam spreading in all directions, with the S edge of this swell reaching as far S as 28N. Please read the latest High Seas Forecast issued by the Ocean Prediction Center at the website https://ocean.weather.gov/mobile/mobile_product.php?id=NFDHSFAT1 and the latest NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. The remnants of Tropical Depression VICTOR is near 18.8N 45.2W at 04/1500Z or about 1225 nm W of the Cabo Verde Islands, and moving WNW or 300 degrees at 13 knots. The estimated minimum central pressure is 1011 mb. The maximum sustained wind speeds are 25 knots with gusts to 35 knots. Seas are peaking at 8 to 10 ft near and up to 220 nm NE of the center. Strong vertical wind shear along with dry air at mid levels have hindered any significant convection near Victor. For the same reason, Victor has opened up into an inverted trough this afternoon, and might be dissipated on Tue. Please, read the latest High Seas Forecast issued by the National Hurricane Center at the 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. A strengthening 1027 mb Azores high is generating near-gale NNE to NE winds near the Canary Islands. For more information, please read the METEO-FRANCE high seas forecast at the following website, http://weather.gmdss.org/II.html ...TROPICAL WAVES... An Atlantic tropical wave is along 31W from 19N southward and moving W at 15 to 20 kt. Scattered moderate to isolated strong convection is seen from 04N to 10N between 28W and 34W. A Caribbean tropical wave is near 75W from 17N southward into N and central Colombia, and moving W near 15 kt. Aided by divergent flow aloft, scattered heavy showers and thunderstorms are occurring over the central and N central Caribbean Sea, including Jamaica and S Hispaniola. ...MONSOON TROUGH/ITCZ... A modest monsoon trough passes through the coast of Mauritania near 18N16W to just E of the Cabo Verde Islands at 17N21W. Scattered moderate convection is found S of the trough axis over the Senegal and Gambia coast from 12N to 14N. Farther SW, the ITCZ extends from 07N21W to 06N30W, and from 05N33W to 04N42W. Scattered moderate to isolated convection is present up to 150 nm along both sides of the first ITCZ. Scattered moderate convection is evident up to 240 nm along both sides of the second ITCZ. The eastern end of the E Pacific monsoon trough is triggering scattered heavy showers and thunderstorms across the SW Caribbean Basin, including the Nicaragua coast. ...GULF OF MEXICO... A modest cold front stretches southwestward from S Louisiana across the NW Gulf to near the Texas-Mexico border. This feature is producing scattered showers and isolated thunderstorms over the N central and NW Gulf, including the Florida Panhandle. A surface trough over the central Bay of Campeche is causing scattered showers and thunderstorms along the SW edge of the Gulf, including the Mexico coastline. Locally moderate to fresh winds and seas up to 4 ft are possible near these thunderstorms. Otherwise, weak surface ridging is supporting light to gentle winds and seas of 1 to 3 ft over much of the Gulf. For the forecast, a weak surface ridge extending southeastward from a 1019 mb high over N Texas will move eastward through Wed, supporting tranquil conditions across all but the southeast sections of the basin. The modest cold front currently over the NW Gulf will move SE across the Gulf through Tue, before stalling across the central Gulf. ...CARIBBEAN SEA... Convergent trades are producing scattered showers and a few thunderstorms along the coast of Belize and Honduras, and adjacent waters. Refer to the Tropical Waves and Monsoon Trough/ITCZ sections for additional convection in the basin. Tightening gradient between the Bermuda high and E Pacific monsoon trough is generating fresh to strong trade winds with seas of 7 to 10 ft across the central basin. Moderate to fresh trades and seas at 6 to 8 ft are evident over the E basin. Gentle to moderate trades and seas of 3 to 5 ft prevail for the rest of the basin. For the forecast, the Bermuda high will gradually slide towards the east through Wed. This pattern will produce fresh to strong trade winds across the NE and central Caribbean through Tue night. Fresh to strong trade winds will then persist across the central Caribbean through Thu. Moderate N to NE swell generated by distant Hurricane Sam over the N central Atlantic will continue to affect waters near Puerto Rico, the Virgin and Leeward Islands through Wed. ...ATLANTIC OCEAN... An robust upper-level trough stretches north-northeastward from E Cuba across the central Bahamas to the N Carolina coast. Together with its related surface trough in the vicinity, scattered showers and thunderstorms are occurring from the central and SE Bahamas northeastward to just S of Bermuda. Farther E, a developing surface trough N of Victor's remnants is triggering similar conditions from 21N to 26N between 38W and 46W. Refer to the Tropical Waves and Monsoon Trough/ITCZ sections for additional convection in the Atlantic Basin. 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 cloud reaching 10,000 ft or 3000 m is drifting southward from the volcano. 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 Bermuda and Azores highs, together with swells from distant Hurricane Sam are promoting gentle to moderate winds with seas at 5 to 7 ft N of 24N between 42W and the Florida-Georgia coast, and N of 10N between 27W and 42W. Farther E, fresh to strong with locally near-gale NE winds and seas at 6 to 9 ft are found near the Canary Islands; N of 18N between the NW African coast and 27W. Gentle to moderate winds and seas of 4 to 6 ft prevail across the remainder of the basin. For the forecast W of 45W, swells generated by Hurricane Sam will continue to impact the SW N Atlantic including the Bahamas E of 70W today through Wed. High pressure along the mid Atlc coast will slide slowly eastward through mid week. This will produce moderate to fresh trade winds S of 23N and E of the Bahamas through Tue before spreading into the SE Bahamas Wed night. Active weather is expected to develop across the waters E of 75W and NE the Bahamas tonight through Tue as a surface trough develops across the SE Bahamas and shifts slowly NW. $$ Chan