AXNT20 KNHC 201527
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 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 1200 UTC surface analysis and satellite imagery through
The axis of a tropical wave is near 37W from 12N southward,
moving westward around 15 kt. No significant surface component
of this wave is noted. Scattered moderate isolated strong
convection is noted from 02N-09N between 24W-40W.
The axis of a tropical wave is near 59W south of 18N, moving
westward around 15 kt. No significant surface component of this
wave is noted. Scattered moderate convection is noted from 10N-
12N between 56W-58W.
The axis of a tropical wave is near 66W south of 20N, moving
westward around 10 kt. The wave is identifiable from surface obs
as well as the San Juan and Sint Maarten 700 mb rawindsonde
winds. Isolated moderate convection is noted from 13N-19N
The monsoon trough axis extends off the coast of Senegal from
13N17W to 10N20W. The ITCZ continues from 10N20W to 04N40W.
Scattered moderate isolated strong convection is noted from 02N-
09N between 24W-40W, from 03N-10N between 00W-10W, and from 08N-
10N between 48W-52W.
GULF OF MEXICO...
High pressure centered over the SE United States is inducing
gentle to moderate E winds over the E Gulf with gentle and
weaker winds elsewhere. Seas are 3-5 ft in the E Gulf and 1-3
ft in the W Gulf. A surface trough in the SW Gulf of Mexico is
associated with isolated moderate convection south of 22N and
west of 93W. Scattered moderate convection is also occurring
north of 27N between 87W and 93W.
For the forecast, the high pressure ridge will dominate the Gulf
waters during the forecast period. Moderate to fresh easterly
winds are expected over the north-central and NE Gulf today, and
across the SE Gulf into Thu. Gentle to moderate winds will
A weak N-S pressure gradient is inducing only gentle to moderate
trades across the Caribbean this morning. Seas are generally 3-
5 ft. Scattered moderate and isolated strong convection is noted
in the NW Caribbean north of 16N and west of 82W. The eastern
North Pacific monsoon trough extends eastward along 10N to a
weak 1010 mb Colombia Low at 10N77W. Scattered moderate and
isolated strong convection is occurring in association with the
monsoon trough in the SW Caribbean south of 11N.
For the forecast, high pressure building N of the area will
bring fresh to locally strong trades E of the Windward Islands
into Sun night. 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.
A cold front extends from 31N52W to 27N59W where it transitions
to a stationary front to 24N67W where that transitions to a
trough to 23N73W. N to NE winds north of the front are moderate
to fresh. Seas peak 8 to 10 ft north of 30N between 58W-62W in
NW swell with seas 4-7 ft elsewhere. South of the front, the E
trades are also moderate to fresh with seas 3-5 ft. Scattered
moderate convection is noted within 60 NM of the front. A pair
of weak troughs exist east and south of the front, though these
have only moderate or weaker winds and no significant deep
convection. A 1029 mb Azores High is driving moderate to fresh
NE to E trades north of the ITCZ. Seas are generally 5-8 ft.
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. Elsewhere, ash plume with weak
concentrations drifting northwest. Marine and aviation interests
should monitor this ongoing situation by reading the Volcanic
Ash Advisory issued by Meteo-France at
For the forecast west of 65W, a stationary front from 25N65W to
the central Bahamas will gradually dissipate through Thu. High
pressure building in the wake of the front will shift eastward
across the W Atlantic along 31N-32N through Thu, producing
moderate to fresh winds immediately north of the front.