[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 081727
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Wed Dec 8 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...

East Atlantic Gale Warning: A strengthening Azores high will
tighten the pressure gradient off the coast of Morocco,
generating N-NE gales in the marine zone Agadir and the northern
part of Tarfaya beginning tonight at 09/0300 UTC and persisting
through at least 09/1200 UTC Thursday. Expect seas of 12-15 ft
within the area of gale force winds. Please read the latest High
Seas Forecast issued by Meteo France at website
http://weather.gmdss.org/II.html for more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough remains inland in Africa. The ITCZ extends
from the coastal plains of Sierra Leone near 07N13W to 04N30W to
the coast of Brazil near 04N51W. Scattered moderate to isolated
strong convection is noted from 04N-07N between 30W-45W.

GULF OF MEXICO...

A stationary front extends from the coast of Louisiana near 29N91W
to a 1014 mb low pressure system in the NW Gulf near 28N95W.
Regional radar indicates that this system is producing a line of
showers and thunderstorms across the northern Gulf of Mexico, east
of 91W. A surface trough southeast of this boundary is also
producing isolated showers and thunderstorms in the north-central
Gulf, north of 27N. A 1019 mb high pressure center near Lake
Okeechobee is generating gentle to moderate anticyclonic breezes
across the basin with 2-3 ft seas.

For the forecast, high pressure along the Mississippi valley will
shift E today, and the stationary front will transition to a
cold front before dissipating 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 the
next cold front forecast to enter the NW Gulf by Sat morning.
Increasing winds and building seas are expected in the wake of the
front. Frequent gusts to gale force are possible behind the
front.

CARIBBEAN SEA...

Ridging from subtropical high pressure is interacting with low
pressure over the Colombian Basin to produce enhanced easterly
flow over the region. Recent scatterometer data provides
observations of fresh trades in the south-central Caribbean with
fresh to strong winds expected near the coast of Colombia. These
winds are generating 8-10 ft seas in the south-central Caribbean
extending from the coast of Colombia and Panama to 16N. The
remainder of the eastern and north central Caribbean is dominated
by gentle to moderate easterly winds with seas 5-7 ft. Trades in
the northwest Caribbean are gentle to moderate with 3-5 ft seas.

For the forecast, the pressure gradient between the ridge across
the northern Caribbean Sea and the Colombian/Panamanian low will
support fresh to strong trade winds over the south-central
Caribbean and in the Gulf of Venezuela through Sun night. Moderate
to fresh trades will prevail elsewhere except in the NW Caribbean
where mainly gentle to moderate winds are expected through Thu.
High pressure will strengthen over the western Atlantic Thu night,
and fresh to locally strong NE winds will develop in the Windward
Passage, the lee of Cuba and S of Hispaniola through Sun night.

ATLANTIC OCEAN...

Refer to the special features section above for details on the
Gale Warning in the east Atlantic. A strong 1037 mb high pressure
near the Azores is the dominate feature. The interaction between
this high pressure and low pressure near the ITCZ is producing
gentle to moderate E-SE winds west of 65W with 4-6 ft seas.
Between 65W and 50W, moderate to fresh easterly flow with 6-8 ft
seas are noted on scatterometer and altimeter data. East of 50W,
fresh to strong NE-E winds prevail with 8-10 ft seas.

For the forecast west of 65W, high pressure over the Mississippi
Valley will push a cold front off NE Florida by this evening. The
front will move across the northern forecast waters through Thu
night before dissipating. High pressure will build across the
region in the wake of the front, producing moderate to fresh NE to
E winds S of 22N, and mainly gentle to moderate winds N of 22N
Thu night through Sun night.

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 to medium ash concentration is expected near and
SW of the volcano.

$$
FLYNN
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