000 AXNT20 KNHC 200603 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Wed Oct 20 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...TROPICAL WAVES... The axis of a tropical wave is near 33W from 02N to 14N. It is moving westward around 15 kt. Some slight cyclonic turning is noted east of the wave near 03N32W. Scattered moderate to isolated strong convection is within 120 nm west of the wave from 07N to 09N. Scattered moderate convection is within 60 nm east of the wave from 07N to 08N. The axis of a tropical wave is near 56W south of 19N to inland Suriname. It is moving westward around 15 kt. This wave is noticeable in the GFS 700 mb streamlines. The CIRA LPW animation imagery shows a moisture maximum trailing this wave east to 52W. Within this area of moisture scattered showers and isolated thunderstorms are noted from 08N to 10N. A dry air slot precedes the wave west to 59W. The A recent ASCAT pass indicates a northeast to southeast wind shift across the wave axis with speeds of gentle to moderate. A pocket of fresh to strong east- southeast winds is east of the wave axis from 08N to 11N between 53W-54W. The axis of a tropical wave is along 64W south of 19N to inland Venezuela, moving westward at 10-15 kt. The GFS 700 mb streamlines capture this wave in a subtle way. Scattered showers and a few thunderstorms are seen east of the wave axis to 62W and from 11N to 15N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends off the coast of Africa near the border of The Gambia and Senegal at 12N16W to 09N21W. The ITCZ continues from 09N21W to 06N27W and to 03N44W. It resumes just to the west of the tropical wave that is near 33W to 02N43W. Aside from convection associated to the tropical wave near 33W, scattered moderate to isolated strong convection is north of the ITCZ from 05N-07N between 35W-39W. Scattered moderate convection is within 120 nm south of the ITCZ between 23W-27W. GULF OF MEXICO... A 1023 mb high center is located just north of the area near 32N80W. A rather extensive surface trough extends from the northwest Gulf of Mexico near 28N94W to 25N92W and to the eastern Bay of Campeche near 18N93W. Moderate to fresh easterly winds are noted over the basin north of 27N between 88W and 94W, and east of 88W as well due to the pressure gradient between the trough and high. Seas are 3-6 ft across these same waters. Mainly light to gentle winds and seas of 2-4 ft continue elsewhere. For the forecast, a ridge will dominate the Gulf of Mexico waters during the forecast period. Moderate to fresh easterly winds are expected over the north-central and NE Gulf waters through Wed, and across the southeastern Gulf through Wed night. Gentle to moderate winds will prevail elsewhere. CARIBBEAN SEA... A weak pressure pattern exists across the Caribbean waters with gentle to moderate trades prevailing, except light to gentle south of 11N in the SW Caribbean. Seas are mainly 2-4 ft, except 1-3 ft in the western Caribbean south of 18N. Satellite imagery shows enhanced cloudiness and convection of the scattered moderate to isolated strong type intensity covering most of the western Caribbean waters from about 11N to 22N and west of 80W. This activity is under a large upper-level anticyclone providing light winds and ventilation over it. Upper-level disturbances riding along the southern branch jet stream that stretches across the crest of the aforementioned anticyclone may be further aiding this convection to some extent. Expect for this convection to change little through at least Wed. Scattered showers and a few thunderstorms are over the extreme southwestern Caribbean south of 11N and west of 76W, mainly due to atmospheric instability from the eastern segment of the eastern Pacific monsoon trough that protrudes into that part of the Caribbean. Isolated showers and thunderstorms are over the Windward Passage. Isolated showers are over some sections of the northeast Caribbean waters. For the forecast, high pressure building north of the area will bring fresh to locally strong trades east of the Windward Islands Wed through Sun. During this period, moderate to fresh winds are expected over the south-central Caribbean, with winds reaching locally strong in the Venezuela basin. Gentle to moderate tradewinds will prevail elsewhere. ATLANTIC OCEAN... A cold front extends from near 31N55W to 26N65W, where it becomes stationary to 24N72W and dissipating to the central Bahamas. A recent ASCAT pass shows moderate to fresh northeast to east winds within about 120 nm north of the frontal boundary and gentle northeast to east winds elsewhere north of the boundary. Scattered showers and isolated thunderstorms are within 60 nm southeast of the cold front north of 27N. Isolated showers are possible elsewhere near and along the frontal boundary. Seas are mainly 3-6 ft west of the front. Northeast of the Lesser Antilles, a trough extends from near 28N40W to 26N46W. Another trough extends from near 29N45W to 25N54W and to 17N61W. A recent ASCAT pass reveals generally light to gentle winds near these troughs. Scattered moderate convection is seen from 29N to 30.5N and between 43W-45W due to mainly an upper-level disturbance that is riding northeastward along a jet stream branch located just to the northwest of the second trough. Farther east, a stationary front enters the discussion waters from 31N26W to 28N29W, then transitions to a trough to near 27N31W. Winds west of the front and trough to 35W are moderate to fresh in speeds along with 5-8 ft seas in a northwest to north swell. Isolated showers are possible near and along the front and trough. North of the ITCZ to 21N, the northeast to east trades are moderate to fresh in speeds, with gentle to moderate winds elsewhere. Seas are mainly 4-7 ft in mixed swell across the remainder of the waters. The Cumbre Vieja volcano, on the island of La Palma in the Canary Islands, has been erupting since 19 September 2021. Ash emission is on-going. Moderate to high volcanic ash is expected in the vicinity of the volcano. It is light elsewhere. Marine and aviation interests should monitor this ongoing situation by reading the Volcanic Ash Advisory issued by Meteo- France at http://vaac.meteo.fr/volcanoes/la- palma/. For the forecast west of 65W, the stationary front will gradually dissipate through Thu. High pressure in the wake of the front will shift eastward across the western Atlantic along 31N- 32N through Thu, producing moderate to fresh winds immediately north of the front. $$ Aguirre