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Atlantic Tropical Weather Discussion



077 
AXNT20 KNHC 251625
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Mon Oct 25 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 
1625 UTC.

...TROPICAL WAVES...

The axis of a tropical has been repositioned along 22W based on
recent scatterometer satellite data and visible satellite imagery
showing a sharp surface trough SE of the Cabo Verde Islands. The
wave is south of 17N and it is moving W at around 10 kt. A few
showers and isolated thunderstorms are noted within 200 nm on both
sides of the wave axis. Fresh to strong trades are noted in 
recent satellite-derived data from 11N to 15N and between 18W and
24W.

The axis of a tropical wave is along 64W, south of 19N and it is
moving W at 10-15 kt. A recent scatterometer satellite pass
indicate a broad surface curvature near the NE coast of Venezuela.
Scattered moderate convection is observed from NE South America to
13N and between 56W and 66W.

The axis of a tropical wave is along 77W, south of 18N, and it is 
moving W at 10-15 kt. Dry air is suppressing the shower and
thunderstorm activity in the Caribbean Sea, but the wave is
helping to induce scattered moderate convection in the Pacific
coast of Colombia.

...MONSOON TROUGH/ITCZ...

A monsoon trough exits across the coast of Senegal near 14N17W 
and continues to 08N23W. The ITCZ then extends from 08N23W to 
06N37W and to the coast of NE Brazil near 03N51W. Scattered 
moderate convection is seen within 220 nm on both sides of the 
ITCZ between 27W and the coast of Brazil. Scattered moderate 
convection is also present within 150 nm on the south side of the 
monsoon trough E of 20W.

...GULF OF MEXICO...

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 is S of 25N and E of 86W, affecting portions of the
Florida Keys and Florida Straits. A few showers are seen in the 
SW Gulf, mainly within 60 nm of the coast of Mexico. A surface 
trough is identified in the E Bay of Campeche and another one 
extends from SE Louisiana to the Big Bend region of Florida, but 
they are 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 produced gentle to moderate winds. Fresh to
strong southerly winds will develop in 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 winds may also occur, mainly over the north-central and NE 
Gulf Wed night to Fri as the pressure gradient tightens across the
area.

...CARIBBEAN SEA...

Aside from the storm activity associated with the tropical waves
moving across the Caribbean Sea discussed in the Tropical Waves
section, only a few showers 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 1026 mb 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 the latest 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 Atlc ridge prevails across the W Atlc
this morning. 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 through 
tonight. A cold front will reach the NW Caribbean Thu night into 
Fri morning, with seas building to 8-9 ft in the Yucatan Channel 
later on Fri.

...ATLANTIC OCEAN...

An intensifying low pressure system off the coast of Georgia 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, affecting the NW Bahamas. Recent scatterometer satellite 
data indicate that fresh to strong winds are occurring W of 70W 
and N of 26N. Elsewhere in the basin, a weak surface trough 
extends from 25N44W to 17N41W, but it is not producing any deep 
convection. Another weak surface trough peeks into the tropical 
Atlantic, entering the region near 31N53W to 29N54W. A few showers
are seen near and east of the trough axis, mostly north of our 
area. 

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 this morning. 1013 low pres along the SE 
Georgia coast will move NE through Tue and then generally north-
northeastward through the middle of the week. The associated cold 
front will move eastward across the northern forecast waters today
with fresh to strong southerly winds and building seas expected 
ahead of the front. Another cold front will push off NE Florida 
coast on Tue, and bring more fresh to strong winds across the 
waters N of 27N. A third 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. 

$$
DELGADO