[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181737
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 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 1200 UTC surface analysis and satellite imagery through
1700 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 today. Seas will build to around 15 ft
with the gale-force winds. Conditions should diminish below gale-
force 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 07N14W. The ITCZ extends from
07N14W to 05N21W to 06N39W. A surface trough is west of the
ITCZ, extending from 09N37W to 03N42W. Scattered moderate
convection is noted from the equator to 08N and between 36W to
43W. Similar convection is within 210 nm on either side of the
ITCZ between 25W to 35W.

GULF OF MEXICO...

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

As of 1500 UTC, a cold front has entered the northwestern Gulf
of Mexico extending from near Galveston, Texas to near The Padre
Island National Seashore, Texas. Fresh to strong NW winds are
west of the front. A surface trough preceding the front is
associated with a line of strong convection extending from Grand
Isle, Louisiana to the central Gulf near 25N93W. Convection is
within 30 nm east of the trough.

Deep moisture and divergence aloft over the southeast Gulf is
leading to scattered convection mainly east of 85W, including
the Florida Straits. Fresh E winds prevail over the Florida
Straits and far SE Gulf, otherwise gentle to moderate winds
dominate ahead of the front. Seas are 4 to 6 ft in the SE Gulf,
and 2 to 4 ft elsewhere.

For the forecast, the cold front moving offshore Texas will
bring strong winds and rough seas over the western and portions
of the northern Gulf, reaching gale force off Veracruz Fri. The
front will stall from near Naples, Florida, to the Bay of
Campeche this weekend, before dissipating. 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 along the coast of The Yucatan Peninsula
southward into the Gulf of Honduras. Most of the scattered
moderate convection associated with this trough has moved north
of the basin into the Gulf, however lingering showers and
thunderstorms are north of 20N offshore western Cuba. Elsewhere
across the Caribbean, dry conditions prevail.

The pressure gradient between the strong subtropical ridge near
Bermuda and lower pressures across N South America result in
fresh to strong NE to E winds across the central Caribbean. The
latest ASCAT pass shows the strongest winds are occurring south
of Hispaniola. Elsewhere, winds are mainly moderate to fresh.
Seas of 6 to 9 ft are occurring in the area of strong winds,
with 5 to 7 ft seas in the eastern Gulf and 4 to 6 ft elsewhere.

For the forecast, the fresh to locally strong 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 Mon and reaching the Yucatan
Channel by late Mon night.

ATLANTIC OCEAN...

A cold front enters the tropical Atlantic near 31N44W and
extends to 23N60W, then continues westward as a dissipating cold
front to 24N69W, and finally transitions to a shear line that
continues to the central Bahamas. No convection is associated
with this boundary. Fresh to strong winds are occurring north of
the cold front and shear line, extending to 30N with seas of 8
to 10 ft. Fresh NE to E winds with seas up to 7 ft are south of
the front and west of 50W.

Farther east, scatterometer satellite imagery revealed weak
surface troughing from 23N31W to 18N43W surrounded by gentle
winds left in the wake of a lingering low pressure center. No
significant precipitation is associated with this feature. North
of the surface trough, an area of moderate to fresh E winds is
north of 28N between 25W and 40W. Seas of 6 to 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, The shear line will dissipate today in advance
of a cold front that will move off the NE Florida coast Fri. The
front will stall from along roughly 28N this weekend, before
lifting north ahead of a strong front that will move off the
northeast Florida coast late Mon. The second front will reach
from Bermuda to eastern Cuba by late Tue.

$$
MORA
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