[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111005
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Mon Oct 11 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
1000 UTC.

...TROPICAL WAVES...

A tropical wave located along 54W or about 350 nm east-southeast of
the Windward Islands continues to produce disorganized cloudiness
and thunderstorms. Some slow development is possible during the
next day or two while the system moves west-northwestward at about
10 to 15 kt toward the Lesser Antilles. After that time, strong
upper-level winds are expected to limit further development.
Regardless of development, the system could produce locally heavy
rainfall and gusty winds across portions of the central and
northern Lesser Antilles on Tuesday, and across the Virgin Islands
and Leeward Islands on Wednesday.

Another tropical wave located over the eastern Caribbean Sea along
67W/68W is producing a large area of disorganized cloudiness and
showers. Unfavorable upper-level winds are expected to limit
development over the next day or so, but environmental conditions
could become a little more conducive for some gradual development
of the system when it is located near the southeastern Bahamas
around midweek. Regardless of development, locally heavy rainfall
is possible over portions of the Lesser Antilles, Puerto Rico, and
Hispaniola during the next couple of days. Satellite derived wind
data clearly indicate the wind shift associated with the wave
axis, with fresh to locally strong E to SE winds behind the wake,
and moderate to locally fresh NE to E winds ahead of the wave
axis.

A third tropical wave is near 83W and extends from just S of the
Isle of Youth, Cuba to Costa Rica, moving W at 15 to 20 kt.
Scattered showers are near the wave axis.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends through the coast of Senegal near Dakar
to S of the Cabo Verde Islands to 08N30W. The ITCZ stretches from
08N30W to 06N47W. Scattered moderate isolated strong convection
is noted from 04N to 08N between 15W and 21W. Scattered moderate
convection is from 04N to 08N between 30W and 40W.

...GULF OF MEXICO...

A ridge dominates the Gulf waters. Recent scatterometer data show
moderate to fresh southerly return flow over the NW Gulf ahead of
a cold front approaching the coast of Texas. Mainly moderate to
fresh SE to S winds prevail over the western Gulf, particularly W
of 94W, while gentle to moderate E to SE winds are noted elsewhere.
Seas are 4 to 6 ft over the NW Gulf, 3 to 5 ft over the remainder
of the W Gulf N of 22N W of 94W, and 1-3 ft elsewhere.

For the forecast, a ridge will continue to dominate 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.

...CARIBBEAN SEA...

A tropical wave is moving across the eastern Caribbean, and a second
tropical wave is forecast to approach the Lesser Antilles on Tue.
Please, see the Tropical Wave section for more details. Both
systems have a low chance of tropical cyclone formation through
48 hours, and also through 5 days. Outside of the tropical wave
located over the eastern Caribbean, moderate trades are noted S of
Hispaniola, with gentle to moderate winds elsewhere across the
basin. Seas are 4-6 ft near the tropical wave, 3-5 ft over the
remainder of the E and central Caribbean, and 1 to 3 ft over the
NW caribbean.

Convection continues to flare-up over eastern Cuba ahead of an
upper-level trough that crosses just E the Isle of Youth, Cuba
to the Gulf of Honduras. Fresh to strong winds are seen per
scatterometer data just S of eastern Cuba due to the convective
activity.

For the forecast, the tropical wave currently located along 54W
could produce locally heavy rainfall and gusty winds across
portions of the central and northern Lesser Antilles on Tuesday,
and across the Virgin Islands and Leeward Islands on Wednesday. A
second tropical wave now moving across the eastern Caribbean, with
axis along 67W/68W will move over Hispaniola today. Locally heavy
rainfall is possible over portions of the Lesser Antilles, Puerto
Rico, and Hispaniola during the next couple of days in association
with this second tropical wave. A northerly swell event over the
Atlantic waters will reach the NE Caribbean passages by Tue.

...ATLANTIC OCEAN...

A surface trough extends southwestward from a non-tropical low
pressure area located just off the North Carolina across the NW
Bahamas to western Cuba. This trough continues to support scattered
showers and thunderstorms. An area of showers and thunderstorms is
just E of the central Bahamas and covers the waters from 23N to
27N between 71W and 75W. A diffluent pattern aloft is helping to
induce this convective activity. Another area of scattered showers
with embedded thunderstorms is noted N of 26N between 30W and
40W. This convective activity is associated with a pre-frontal
trough that extends from 31N30W to 27N50W. The remainder of the
Atlantic is under the influence of a ridge, anchored on a 1032 mb
high pressure located well NE of the Azores. The pressure
gradient between the ridge and lower pressures over W Africa is
resulting in a belt of moderate to fresh trade winds roughly from
17N to 22N and E of 40W to the coast of Mauritania.

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, then eastward later today.
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/.

For the forecast W of 65W, the surface trough located just E of
Florida and associated weather will move little today, then drift
E and weaken through midweek. Farther south, a low pressure is
forecast to develop around mid-week near the SE Bahamas. This will
be associated with the northern extent of a tropical wave currently
moving across the eastern Caribbean. A northerly swell event across
the Atlantic will reach the SE waters by Tue.

$$
GR
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