000 AXNT20 KNHC 131029 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Wed Oct 13 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 1030 UTC. ...TROPICAL WAVES... An Atlantic tropical wave has its axis along 28W, south of 18N and it is moving W at 10-15 kt. Scattered moderate to isolated strong convection is observed from 04N to 12N and between 27W and 31W. Another Atlantic tropical wave has its axis along 49W/50W, south of 18N and it is moving W at 15 kt. Scattered moderate to isolated strong convection is noted where the wave interacts with the ITCZ from 05N to 12N and between 48W and 52W. The northern portion of the wave is surrounded by dry Saharan air and subsident northerly flow aloft, suppressing the development of showers and thunderstorms. A Caribbean tropical wave has its axis along 65W, south of 20N, extends from the Virgin Islands to E Venezuela, and it is moving W at 10-15 kt. Scattered moderate to isolated strong convection is seen on satellite imagery from 15N to 20N and between 63W to 65W. Overnight scatterometer satellite pass show fresh to strong SE-S winds within 170 nm to the E of the wave axis, mainly from 15N and 20N. A second Caribbean tropical wave has its axis along 80W, south of 20N and it is moving W at 10-15 kts. No deep convection is noted in association with the wave as it moves across very dry airmass. ...MONSOON TROUGH/ITCZ... A monsoon trough extends from the coast of Senegal near 11N16W to 05N30W. The ITCZ continues from 05N30W to 05N40W to 07N49W, then continues W of a tropical wave near 05N51W to the coast of Suriname near 06N54W. Scattered moderate convection is noted along the monsoon trough from 04N to 09N between 15W and 28W. Scattered moderate to isolated strong convection is noted along the ITCZ from 06N to 10N between 33W and 54W. ...GULF OF MEXICO... A weak ridge over the eastern United States extends to the Gulf of Mexico and maintains tranquil weather conditions across the basin. The pressure gradient between the ridge and lower pressures across the southern United States and northern Mexico results in fresh SE winds across the western Gulf waters, especially W of 94W. Seas in this region are 3-6 ft. Moderate or weaker anticyclonic winds with seas of 1-3 ft are prevalent elsewhere in the Gulf. For the forecast, high pres extends extends weakly from the eastern U.S. southwestward to the N central Gulf and will influence the Gulf waters during the next several days. Moderate to fresh southerly winds are expected over the western Gulf between the ridge and lower pressure over the Southern Plains and northern Mexico through Thu. Gentle to moderate breezes will persist elsewhere through Fri. A cold front enter the NW Gulf Fri night with fresh to strong northerly winds following it. The front will reach central Florida to western Bay of Campeche Sun morning with moderate to fresh N-NE winds across most of the Gulf. ...CARIBBEAN SEA... An upper level trough off the SE United States extends to the NW Caribbean Sea allowing for scattered showers and isolated thunderstorms from the coast of Colombia to Hispaniola, between 70W and 70W. A surface trough extends from southern Florida to the Gulf of Honduras and a few shallow showers are seen near the trough axis. The rest of the basin remains fairly quiet outside of the tropical wave in the E Caribbean previously described in the Tropical Waves section. Fresh trades are noted within 150 nm of the coast of NE Venezuela, including the waters surrounding the ABC islands. Moderate or weaker trades prevail elsewhere. Seas of 3-5 ft are occurring in the E, central and SW Caribbean, while 1-3 ft are present elsewhere. For the forecast, a tropical wave along 64W will move westward through tonight, and spread fresh winds and very active weather across the extreme NE Caribbean and adjacent Atlc waters. Northerly swell will build across the regional Atlc and move through the Caribbean passages through late Wed. Active weather associated with an upper level trough along 59W will continue through Wed morning. Low pres is expected to develop E of the southern Bahamas on Thu and drift eastward into the weekend. This will weaken the pressure gradient across the Caribbean basin leading to tranquil marine conditions. ...ATLANTIC OCEAN... Recent scatterometer satellite data depict a well-defined surface trough extending from near the northern coast of Haiti to 28N71W. This feature is interacting with an upper level trough located to the west, producing a large area of scattered showers and isolated thunderstorms, mainly from 20N to 31N and between 62W and 75W. Satellite-derived wind data indicate fresh to strong cyclonic winds within 100 nm of the coast of Hispaniola. The other feature of interest in the tropical Atlantic is a 1004 mb low pressure located just north of our area, but a surface trough extends south to 24N46W. Scattered moderate convection is observed on satellite imagery within 170 nm of the trough axis. Scatterometer satellite data indicate fresh to strong cyclonic winds N of 28N and between 44W and 55W. Fairly tranquil weather conditions and moderate or weaker winds prevail elsewhere in the basin. Widespread northerly swell continues impact the region, reaching 8-11 ft mainly north of 15N between 30W and 65W. 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 2021. Currently, significant volcanic ash is seen in the vicinity of the volcano drifting southward closer to the surface. Marine and aviation interests should monitor this ongoing situation, by reading the Volcanic Ash Advisory, that is issued by Meteo-France, at http://vaac.meteo.fr/volcanoes/la-palma/. For the forecast west of 65W, high pressure centered over the central Atlantic will shift slowly E and weaken through the end of the week. A low level trough extends from the southern Bahamas to 28N71W. Very active weather is expected with this trough through Wed as it drifts eastward. Low pres may form along the trough by Thu as it shifts E of 60W. Northerly swell across the regional waters will peak tonight E of 70W then begin to fade Wed. $$ AKR