[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091720
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Dec 9 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 strong high pressure of 1037 mb
persists over the Azores. This system is producing a tight
pressure gradient off the coast of Morocco, generating N-NE gales
in the marine zone of Agadir and the northern part of Tarfaya.
These conditions are forecast to continue through 10/0300 UTC.
Expect seas of 10-14 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 has retreated inland in Africa. The ITCZ
extends from the coastal plains of Liberia near 07N10W to 06N30W
to 02N49W off the coast of Brazil. Scattered moderate to isolated
strong convection is noted from 03N-09N between 22W-44W.

GULF OF MEXICO...

A weak stationary front extends from central Florida to 27N89W.
This system is not generating significant weather and has steadily
weakened over the last 24 hours. Gentle to moderate SE flow is
present across the western Gulf of Mexico with light to gentle
winds across the remainder of the basin. Sea heights are
1-3 ft across the majority of the region.

For the forecast, the stationary front will lift back north as a
warm front tonight through Fri. A high pressure ridge extending
from the Atlantic to the central Gulf will gradually shift
eastward through Sat afternoon in response to a strong cold front
that will move over the NW Gulf by early Saturday Moderate to
fresh southerly return flow will set-up across the western and
central Gulf beginning tonight and through Sat ahead of the strong
cold front. Fresh to strong northerly winds and building seas are
expected in the wake of the front through late Sat night.

CARIBBEAN SEA...

The gradient between the high pressure ridging from the subtropics
and low pressure near Colombia and Panama is generating enhanced
easterly trade wind flow through the basin. Recent scatterometer
wind data shows a small region of near gale force NE winds off the
coast of Colombia near 11.5N75.5W, generating up to 8 ft wind
waves. This area is surrounded by a fresh to strong ENE breeze
throughout the central Caribbean with 5-7 ft seas. Moderate to
fresh trades dominate the E basin with 4-6 ft seas. Gentle to
moderate trades prevail across the NW Caribbean with 3-5 ft seas.
Expect isolated to scattered passing showers throughout the basin.

For the forecast, the pressure gradient will continue to support
fresh to strong trades over the south-central Caribbean and in the
Gulf of Venezuela through Fri night. Moderate to fresh trades
will prevail elsewhere. High pressure will strengthen over the
western Atlantic by tonight, and fresh to locally strong northeast
winds will develop in the Windward Passage, the lee of Cuba and
south of Hispaniola through Mon night.

ATLANTIC OCEAN...

A cold front extends from 31N69W to 28N78W where it becomes
stationary and extends to central Florida. Winds behind the front
are moderate northeasterly. A pre-frontal surface trough is noted
from 26N27W to 31N68W with scattered showers and thunderstorms
within 60 nm of the feature. Ahead of the trough and N of 28N,
winds are moderate to fresh from the S-SW. Gentle to moderate
winds are noted elsewhere west of 65W generating 4-6 ft seas. In
the central Atlantic between 65W and 40W, winds are moderate to
fresh from the east with 6-9 ft seas, increasing eastward. In the
eastern Atlantic, east of 40W, winds are mainly fresh to strong
from the E-ENE due to the enhanced pressure gradient between a
1037 mb high near the Azores and lower pressure over Africa. Seas
are 9-11 ft with localized gale force winds and up to 14 ft seas
along the coast of Morocco as described in the special features
above.

For the forecast west of 65W, the cold front will become
stationary from near 31N59W to 28N78W on Fri and dissipate over
the weekend. 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 through Sat
night. Another cold front will move off the northeast Florida
coast early on Sun, and reach from near 31N65W to South florida by
Sun night. This front is forecast to dissipate over the
southeastern waters on Mon. High pressure behind the front will
likely bring fresh to strong northeast to east winds mainly across
the waters south of 27N by Mon 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 ash concentration is expected near and SW of the
volcano.

$$
FLYNN
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