AXNT20 KNHC 252342

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Tue Oct 26 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 1800 UTC surface analysis and satellite imagery through 2230 UTC.


An Atlantic tropical wave has an axis along 24W from 17N southward, moving W at 10-15 kt. Scattered moderate convection is noted south of the Cabo Verde Islands from 06N to 15N between 23W and 26W. Fresh to strong trades are noted in earlier satellite- derived data near the wave.

A Caribbean Sea tropical wave has an axis along 64W from 18N southward and is moving W at 10 kt. No significant convection is noted with this wave at this time.

A Caribbean tropical wave has an axis along 78W from 18N southward and moving W at 10-15 kt. No significant convection is noted with this wave at this time.


The monsoon trough extends off the coast of The Gambia/Senegal near 13N17W to 07N24W. The ITCZ extends from 07N26W to 06N42W to the coast of Brazil near 04N51W. Scattered moderate convection is within 250 nm of the monsoon trough. Scattered moderate convection is also noted within 150 nm on either side of the ITCZ.


An upper level trough across the central United States and a developing low pressure off the Georgia coast are providing a favorable upper level pattern for scattered moderate to isolated strong convection to flare up in the SE Gulf of Mexico. Most of the convection continues to be S of 25N and E of 85W, affecting portions of the Florida Keys and Florida Straits. A surface trough is analyzed in the central Bay of Campeche but not producing any significant convection. Weak pressure gradient results in moderate or weaker anticyclonic winds prevailing across the basin. However, stronger winds are likely in the areas of showers and thunderstorms. Seas of 2-4 ft are present N of 20N and 1-3 ft elsewhere.

For the forecast, a weak ridge along 25N will dominate the Gulf waters through Tue and produce gentle to moderate winds. Fresh to strong southerly winds will develop across the NW Gulf Tue night into Wed ahead of a cold front expected to push off the Texas coast on Wed. The front will move across the Gulf region through Thu night. Fresh to strong winds are expected ahead and behind the front, with building seas to 12 ft in the wake of the front. Gale force W winds are expected behind the front and N of 26N Thu afternoon through early Fri afternoon before quickly diminishing early Sat.


Aside from the storm activity associated with the tropical waves, only a few showers and isolated thunderstorms are noted near the coast of Panama and SE Costa Rica. A dry airmass dominates the rest of the basin, providing fairly tranquil weather conditions. A modest pressure gradient between the high pressure in the NW Atlantic and lower pressures in South America result in fresh to locally strong trades in the central and eastern Caribbean Sea, with the strongest winds occurring within 100 nm of NW Colombia and in the SE Caribbean based on earlier scatterometer satellite data. Seas of 5-8 ft are found in the central, southwest and eastern Caribbean Sea, with the highest seas occurring off the NW Colombian coast. Moderate to locally fresh, especially in the Gulf of Honduras, and seas of 2-5 ft are present elsewhere in the basin.

For the forecast, a weak ridge persists across the W Atlc to the east of 75W. The associated pres gradient across the Caribbean will support fresh to locally strong trades across the eastern Caribbean and tropical Atlc waters E of the Windward Islands through tonight. Winds are also expected to pulse fresh to strong in the south-central Caribbean, including the Gulf of Venezuela tonight. A cold front will enter the NW Caribbean Thu evening and reach from W central Cuba to the Gulf of Honduras by midday Fri.


An intensifying low pressure system off the U.S. East Coast and a surface trough extending SW to southern Florida are producing a large area of showers and thunderstorms, mainly W of 72W and N of Cuba, impacting portions of the NW Bahamas. Earlier scatterometer satellite data indicated that fresh to strong winds are occurring W of 70W and N of 26N. Elsewhere in the basin, a weak surface trough extends from 27N44W to 20N47W, but it is not producing any deep convection. Another weak surface trough peeks into the tropical Atlantic, entering the region near 31N50W to 29N54W. A few showers are seen near and east of the trough axis, N of 29N between 45W and 53W.

An expansive 1031 mb Azores ridge patrols the rest of the tropical Atlantic, promoting fairly tranquil weather conditions. The pressure gradient between the high pressure system and lower pressures in South America result in fresh to strong trades from 05N to 19N and between 33W and the Lesser Antilles. Seas in this region are in the 7-10 ft range, with the highest seas occurring a couple of degrees east of the Windward Islands. Another area of fresh to strong NE winds is found in the E Atlantic from 15N to 22N and E of 30W. Seas of 3-6 ft are prevalent W of 60N and 5-8 ft are present elsewhere in the basin.

The Cumbre Vieja volcano, on the island of La Palma in the Canary Islands, has been erupting since 19 September 2021. Ash cloud slowly drifting SW. Higher concentration over volcano and western vicinity. 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 W of 65W, weak ridge extends from the central Atlc westward to 75W. 1007 low pres offshore of S Carolina will move NE through Tue and rapidly intensify. An associated frontal trough moving eastward across the northern forecast waters will produce fresh to strong southerly winds and building seas expected ahead of it. A cold front will move off NE Florida coast early Tue, and bring more fresh to strong winds across the waters N of 27N. A next cold front is expected to sweep across the region Thu night through Fri night bringing another round of fresh to strong winds north of the Bahamas.

$$ AReinhart