[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172122
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 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 1800 UTC surface analysis and satellite imagery through
2000 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 12 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 reaches the Atlantic through the coast of
Guinea-Bissau near 12N16W to 09N17W. The ITCZ extends from 09N17W
to 05N22W to 07N31W to 04N45W. Scattered moderate and isolated
strong convection is noted from the equator to 11N between 25W
and 41W.

GULF OF MEXICO...

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

A ridge of high pressure extends across the southeastern United
States with return flow across the basin. Moderate to fresh E-SE
winds are found in the eastern Gulf, strongest in the southeast
Gulf through the Straits of Florida, with gentle to moderate SE-S
winds elsewhere. Seas are 3 to 5 ft across the northern half of
the Gulf, with 4 to 6 ft seas in the southeast Gulf, except to 7
ft through the Straits of Florida, and 2 to 4 ft in the southwest
Gulf. Deep tropical moisture moving in from the northwest
Caribbean is allowing for scattered showers and thunderstorms
embedded within these easterly winds across the southeast and
south-central Gulf.

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 just offshore of the Yucatan
Peninsula extending from near Cozumel, Mexico to the Gulf of
Honduras. This trough combined with deep tropical moisture and
upper-level divergence are producing numerous moderate to
isolated strong convection north of 17N, west of 80W. The rest of
the Caribbean is fairly dry, except for scattered moderate
convection noted just off the coasts of Honduras, Nicaragua,
Costa Rica, and northern Panama, in association with localized
land breezes as well as the eastern extension of the Pacific
monsoon trough along 10N.

High pressure north of the Greater Antilles and lower pressure
across South America is translating to a tight pressure gradient
over the basin, and thus moderate to fresh winds encompass most
of the basin, fresh to strong in the central Caribbean from
southwest of the Dominican Republic to offshore of Colombia.
Seas of 6 to 9 ft dominate the central Caribbean, highest
northwest of Colombia. Seas of 4 to 7 ft prevail in the eastern
Caribbean with 3 to 5 ft in the western Caribbean.

For the forecast, 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 31N51W and extends
to 25N68W, where it transitions to a shear line that continues
across the southeast Bahamas. No significant convection is
occurring along this boundary. Fresh to locally strong winds are
occurring within about 180 nm north-northwest of the boundary,
with 5 to 7 ft seas across the area north of the boundary, locally
to 8 ft near the strong winds.

Farther east, a 1011 mb low pressure is near 25N31W. A weakening
surface trough associated with the low pressure extends from
the low to 23N41W. Scattered moderate convection is noted from 24N
to 30.5N between 26W and 33W. Fresh to locally strong mainly
easterly winds are noted northeast of the low between 28W and
35W, along with 7 to 10 ft seas.

Aside from the winds near the cold front and low pressure, to the
west of 40W, mainly moderate winds prevail except fresh winds
north of the Lesser Antilles to 22N, highest through the Caribbean
passages. Gentle to moderate winds are occurring elsewhere. Seas
of 5 to 8 ft prevail elsewhere across the open Atlantic.

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, high pressure north of the area and the shear
line will shift east tonight, ahead of cold front moving off the
northeast 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.

$$
Lewitsky
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