[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180455
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Thu Nov 18 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
0444 UTC.

...SPECIAL FEATURES...

Gulf of Mexico Gale Warning: Gale-force NW-N winds will develop
offshore of Veracruz Fri afternoon behind a cold front that will
move through the basin. Seas will build to around 15 ft with the
gale-force winds. Conditions should diminish below gale-force by
Fri evening. 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 mostly confined to the African
continent, reaching the Atlantic through the coast of Sierra
Leone near 08N13W and extending to 06N15W. The ITCZ extends from
06N15W to 02N24W to 04N34W, then resumes west of a surface trough
from 04N42W to 02N49W. The surface trough extends from 09N35W to
01N41W. Scattered moderate to isolated strong convection is noted
from the equator to 11N and between 22W to 41W.

GULF OF MEXICO...

Please see the Special Features section above for details on a
Gale Warning in effect near Veracruz, Mexico.

The Gulf of Mexico is in the southwestern periphery of a 1029 mb
high pressure system located near Bermuda. A prominent cold front
sliding SE over the central United States is transporting
tropical moisture northward into the basin, combined with
divergence aloft results in scattered showers over most of the
eastern half of the Gulf, mainly E of 91W and N of 24N. A recent
scatterometer satellite pass show fresh to locally strong E winds
over SE Gulf waters, including the Florida Straits. The rest of
the Gulf enjoys fairly tranquil weather conditions and moderate or
weaker winds. Seas of 4-6 ft are present in the NW and SE Gulf
waters, while 1-3 ft seas prevail elsewhere.

For the forecast, a cold front moving into coastal Texas will enter
the northwest Gulf early Thu. Strong winds and rough seas will
follow the front over the western Gulf, reaching gale force off
Veracruz Fri. The front will stall from near Tampa Bay, Florida
to 24N95W to Veracruz by Sat, then start to dissipate. Looking
ahead, another front will move into the northwest Gulf early
Mon, and reach from southwest Florida to the southwest Gulf by
late Mon night.

CARIBBEAN SEA...

A surface trough extends from the Yucatan peninsula to N Honduras,
across the Gulf of Honduras. Plenty of tropical moisture in the NW
Caribbean and divergence aloft allows for scattered showers and
isolated thunderstorms to affect the waters W of 84W. The rest of
the basin enjoys fairly tranquil weather conditions.

The modest pressure gradient between the strong subtropical ridge
near Bermuda and lower pressures across N South America result in fresh
to strong trades across the central Caribbean, including the
Windward and Mona Passages, and the NW Caribbean N of 20N. A
recent scatterometer satellite pass depict a small area of near-
gale force winds within 100 nm of the Barahona peninsula
in southern Hispaniola. Moderate to locally fresh trades are
prevalent elsewhere. Seas of 6-9 ft are found in the central, SW
and NE Caribbean Sea, with the highest seas occurring offshore
southern Hispaniola. Seas of 2-5 ft prevail elsewhere.

For the forecast, fresh NE winds persist in a broad swath from the
northeast Caribbean into the southwest Caribbean. Winds and seas
will diminish through Fri as high pressure north of the area
shifts east, ahead of a cold front moving into the Gulf of
Mexico and western Atlantic. Winds and seas further diminish
early next week, ahead of a second cold front moving through the
Gulf late Mon and Mon night.

ATLANTIC OCEAN...

A cold front enters the tropical Atlantic near 31N49W and extends
to 24N67W, where it transitions to a shear line that continues
across the central Bahamas. A few shallow showers are noted near
the frontal boundary. Fresh to locally strong winds are occurring
north of the cold front and shear line, extending to 30N. Fresh to
locally strong trades are also present S of 22 and W 55W, with
the strongest winds occurring between Haiti and Great Inagua in
the SE Bahamas, at the entrance of the Windward Passage. Seas of
6-10 ft are present to the W of the cold front and shear line,
with the highest seas occurring N of 29N and between 50W and 58W.

Farther east, a 1012 mb low pressure is near 24N33W. A weakening
surface trough associated with the low pressure extends from the
low to 22N40W. No deep convection is seen in association with the
low pressure or associated trough. Fresh to locally strong mainly
easterly winds are observed N of 28N and between 22W and 29W. Seas
are 5-8 ft prevail in the central and E tropical Atlantic. Moderate
or weaker winds and fairly tranquil weather conditions are
present elsewhere.

The Cumbre Vieja volcano, on the island of La Palma in the
Canary Islands, has been erupting since 19 September 2021.
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, a shear line extends along 25N into the central
Bahamas. Fresh to strong NE to E winds are evident a couple of
hundred miles to the north of this line. The shear line will
dissipate Thu in advance of a cold front that will move off the
NE Florida coast. The front will stall from Bermuda to central
Florida Sat, then lift north again Sun ahead of a stronger front
moving off the northeast Florida coast late Mon. The second front
will reach from Bermuda to eastern Cuba by Tue night.

$$
DELGADO
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