[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071734
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Tue Dec 7 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
1600 UTC.

...SPECIAL FEATURES...

East Atlantic Gale Warning: A strengthening Azores high will
tighten the pressure gradient off the coast of Morocco,
generating localized N-NE gales and 12-15 ft seas by Thursday
morning in the marine zone Agadir. Please ready the latest High
Seas Forecast issued by Meteo-France at website
http://weather.gmdss.org/II.html

...MONSOON TROUGH/ITCZ...

The monsoon trough is over the African continent. The ITCZ
extends from the coast of Sierra Leone near 08N13W to 04N30W to
the coast of South America near 06N55W. Scattered moderate
isolated strong convection is noted from 02N-06N between 28W-
38W.

GULF OF MEXICO...

A cold front extends over the northern Gulf of Mexico crossing
the Florida coast near 29N84W, becoming a stationary boundary
from 29N87W to the Mexican coast near Tampico at 22N98W. A
surface trough extends from the Bay of Campeche to the southeast
Gulf of Mexico with isolated thunderstorms in the vicinity of
24N86W. High pressure of 1019 mb near Tampa Bay extends surface
ridging over the central Gulf generating mainly gentle
anticyclonic winds in the eastern and central Gulf with seas of
1-2 ft. Moderate northerly winds are present northwest of the
stationary front along the coast of Texas and northeastern
Mexico, where seas are 3-4 ft.

For the forecast, the stationary front will retreat inland by
tonight. A ridge will build westward across the basin, with a
high pressure cell remaining over the eastern Gulf. Moderate to
fresh southerly return flow will set-up across the western and
central Gulf on Fri and Sat, ahead of a strong cold front
forecast to push off the Texas coast by Sat morning. Increasing
winds and building seas are expected in the wake of the front.
Gale conditions are possible behind the front during the
upcoming weekend.

CARIBBEAN SEA...

Recent scatterometer data indicates strong to locally near gale
force NE-E winds off the coast of Colombia. These winds are
generating 8-10 ft seas in the south-central and southwest
Caribbean. Fresh to strong trades dominate the rest of the
central and eastern Caribbean with 6-8 ft seas. Moderate trades
are generating 3-5 ft seas in the northwest Caribbean. Dry
conditions dominate the majority of the basin with isolated
passing showers.

For the forecast, high pressure located north of the Caribbean
Sea combined with the Colombian low will support fresh to strong
trade winds over the south-central Caribbean and in the Gulf of
Venezuela through the week. Moderate to fresh trades will
prevail elsewhere except in the NW Caribbean where mainly gentle
to moderate winds are expected. By Thu night into Fri, as high
pressure strengthens over the western Atlantic, expect fresh to
locally strong NE winds in the Windward Passage, and in the lee
of Cuba. This will persist through Sat while extending eastward
toward Hispaniola and Puerto Rico.

ATLANTIC OCEAN...

The combination of a surface trough extending across the
northwest Bahamas to 30N75W and upper-level divergence is
generating scattered showers and thunderstorms east of the
trough axis between 70W and 75W and from 25N to 31N. Farther
east, a second trough is noted from 30N58W to 21N57W. Recent
scatterometer data indicates fresh SE winds east of the trough.
Between the two troughs, surface ridging is keeping winds
gentle. Fresh to locally strong NE to E winds prevail across the
central tropical Atlantic north of the ITCZ between 30W and 50W.
Seas in this area are 7-10 ft. Between 60W and the Bahamas seas
are 3-5 ft. An upper-level low W of the Canary Islands is
generating scattered showers and isolated thunderstorms north of
25N and east of 23W.

For the forecast west of 65W, a ridge will prevail along 26N-27N
through late this week. Moderate to fresh NE to E winds are
expected along the southern periphery of the ridge, especially
south of 22N, including the waters just N of Hispaniola and
approaches to the Windward Passage. A weak cold front will stall
over the far northern waters today, then lift northward by
tonight. Another cold front will move over the northern forecast
waters Thu and Fri while dissipating.

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/. The latest advisory
states that low ash concentration is expected near and W of the
volcano.

$$
Flynn/Hagen
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