[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200507
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Sat Nov 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
0455 UTC.

...SPECIAL FEATURES...

Gulf of Mexico Gale Warning: A stationary front extends from near
St. Petersburg, Florida to inland Mexico near Coatzacoalcos as of
0300 UTC. NW-N gale-force winds are confined to the far SW Gulf
S of 21N and W of 95W, with seas of 8-12 ft. A recent
altimeter satellite pass indicate seas up to 12 ft off Veracruz,
Mexico. Winds will slacken and seas will subside today as the
pressure gradient decreases and the frontal boundary weakens.
Please see the latest NWS High Seas Forecast issued by the
National Hurricane Center at website
www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more information.

...MONSOON TROUGH/ITCZ...

The monsoon trough remains over Africa. The ITCZ begins near
06N16W to 07N30W. A surface trough extends from 16N30W to 03N38W,
interrupting the ITCZ. The ITCZ then resumes near 07N39W to
05N50W. Scattered moderate to isolated strong convection is
observed from 02N to 13N and E of 40W.

GULF OF MEXICO...

Please see the Special Features section above for details on a
Gale Warning that is currently in effect for a section of
the SW Gulf.

The aforementioned stationary front extends from central Florida
to near Coatzacoalcos, Mexico in the SW Gulf. Abundant moisture,
low-level wind convergence and divergence aloft result in a large
area of cloudiness and widespread showers, mainly S of 25N and W
of 87W. Recent scatterometer satellite pass show fresh to strong
NE winds covering most of the basin. The exception being the NW
Gulf where winds have decreased to fresh to moderate. Seas of 6-9
ft are occurring in the SW Gulf outside of the gale warning area,
while 3-6 ft prevail elsewhere.

For the forecast, the previously-mentioned front will drift south
while dissipating this weekend. Strong northerly winds and rough
seas follow the front. Winds to minimal gale force off Veracruz
are ongoing and will gradually diminish tonight. Another cold
front will enter the northwest Gulf early Mon, and move south of
the basin late Mon night. Fresh to strong winds are expected
behind the front. High pressure will build across the Gulf region
in the wake of the front.

CARIBBEAN SEA...

Most of the Caribbean Sea enjoys fairly tranquil weather
conditions. The exception is found within 60 nm of the coast of
Nicaragua where abundant moisture and low-level convergence are
inducing a few showers. The pressure gradient across the basin has
diminished as the strong ridge north of the Caribbean has tracked
eastward and further away from the region. Fresh to locally strong
trades are occurring in the central Caribbean, with the strongest
winds affecting the waters offshore of NW Colombia. Moderate or
weaker winds prevail elsewhere. Seas of 3-6 ft are found in the
SW, central and E Caribbean, while 1-3 ft seas are prevalent in
the rest of the basin.

For the forecast, high pressure north of the area will shift
east, ahead of a cold front moving off NE Florida. Winds and seas
will further diminish early next week, ahead of a stronger cold
front moving through the Gulf of Mexico Mon. The front will reach
the Yucatan Channel by late Mon night and extend from eastern Cuba
to the Gulf of Honduras by late Tue. Fresh to locally strong
winds and building seas are expected in the wake of the front.

ATLANTIC OCEAN...

A cold front extends from the Canadian Atlantic provinces to
central Florida, entering the tropical Atlantic near 31N74W. A
pre-frontal trough extends from 23N to 29N along 78W, crossing the
NW Bahamas. Scattered moderate to isolated strong convection is
noted to the east of the front and trough axis, with the strongest
convection occurring just east of the NW Bahamas. A recent
scatterometer satellite pass show fresh to strong winds N of 24N
and W of 72W. Seas W of 60W are 6-10 ft, with the highest seas
occurring to the north of the frontal boundary.

Farther east, a shear line extends from 31N34W to 23N51W and only
a few isolated showers are seen near its axis, mainly W of 49W.
Satellite-derived wind data show fresh to locally strong N-NE
winds behind the shear line, extending north to 31N. Nearby, a
1011 mb low pressure system is analyzed near 27N32W and surface
troughs extend from the low, southwestward to 18N39W and eastward
to 26N25W. A large area of showers and isolated thunderstorms is
located to the east of the low pressure, mainly N of 27N and
between the low pressure and 21W. Scatterometer satellite data
depict a small area of fresh SE-S winds east of the low pressure.
The rest of the basin enjoys fairly tranquil weather conditions
and moderate or weaker winds.

Seas of 6-10 ft are found N of 20N and between 25W and 60W, with
the highest seas occurring over the open Atlantic near 30N40W.
Elsewhere in the basin, seas of 3-6 ft are prevalent. Northerly
swell, generated by a strong low pressure system located north of
the area, will reach the forecast waters late on Sat, building
seas to 10-14 ft roughly north of about 28N and between 25W-40W
by Sun morning.

The Cumbre Vieja volcano, on the island of La Palma in the Canary
Islands, has been active for two months(since 19 September 2021).
An ash emission is ongoing. Medium ash concentration is noted in
the vicinity of the volcano, low 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 W of 65W, cold front extending from 31N75W to
near Cape Canaveral, Florida will remain across the northern
forecast waters this weekend, before lifting north ahead of a
stronger cold front that will move off the northeast Florida coast
on Mon. The second front will reach from near Bermuda to eastern
Cuba by late Tue. Fresh to strong northerly winds and building
seas are expected behind the fronts.

$$
DELGADO
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