[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 090550
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 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 0000 UTC surface analysis and satellite imagery through
0530 UTC.

...SPECIAL FEATURES...

Eastern Atlantic Ocean Gale Warning: A strengthening area of high
pressure in the Azores will tighten the pressure gradient off the
coast of Morocco. The forecast consists of N to NE gale-force winds
in the marine zone Agadir, and in the northern part of Tarfaya,
during the early morning hours and the sunrise hours of today,
09 December. Expect the sea heights to range from 12 feet to 15
feet within the area of gale force winds. Please read the latest
High Seas Forecast, issued by Meteo-France, at the website
http://weather.gmdss.org/II.html, for more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough remains inland in Africa. The ITCZ passes
through the coastal border areas of Sierra Leone and Liberia,
to 05N21W, 04N30W, and 03N37W. Precipitation: scattered to
numerous strong is from 03N to 08N between 34W and 45W. Scattered
moderate to widely scattered strong is within 90 nm to the north
of the ITCZ and within 120 nm to the south of the ITCZ between 19W
and 36W.

GULF OF MEXICO...

A cold front passes through 31N80W in the Atlantic Ocean, to
29N82W in Florida, to 27N90W, and 26N95W in the NW parts of the
Gulf of Mexico. Precipitation: broken to overcast multilayered
clouds and possible rainshowers are from 24N northward. Moderate
or slower wind speeds cover the area. The sea heights range from 1
foot to 3 feet.

A cold front extending over the northern waters will dissipate
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.

CARIBBEAN SEA...

The GFS model for 250 mb shows a ridge that extends from northern
Colombia to the Yucatan Peninsula of Mexico. The 250 mb wind flow
is purely northwesterly on the northeastern side of the ridge. The
GFS model for 500 mb shows an east-to-west oriented ridge from
Puerto Rico to the Yucatan Peninsula. The GFS model for 700 mb
shows an anticyclonic circulation center in the Yucatan Channel.
Anticyclonic wind flow is to the west of the line from the
Windward Passage to NE Nicaragua. Easterly wind flow covers the
rest of the Caribbean Sea, at 700 mb.

The monsoon trough passes through Colombia near 10N74W, beyond
07N81W in Panama, and into the eastern Pacific Ocean.
Precipitation: isolated moderate to locally strong is within
120 nm to the south of the monsoon trough. Isolated moderate
rainshowers are from 14N southward from 74W westward, with
the low level wind flow, in the SW corner of the Caribbean Sea.

Isolated moderate rainshowers are associated with broken to
overcast low level clouds, that are moving with the low level
wind flow, in the remainder of the Caribbean Sea.

Near gale-force winds are within 125 nm of the coast of Colombia
between 73W and 76W. Strong winds are within 400 nm of the coast
of Colombia between 71W and 80W. Strong to near gale-force winds
are in the Gulf of Venezuela. Fresh winds are elsewhere from 17N
southward from 83W eastward. The sea heights range from 8 feet to
9 feet in the south central sections of the Caribbean Sea. The
sea heights range from 5 feet to 7 feet from 70W eastward. The sea
heights range from 3 feet to 5 feet in the remainder of the
Caribbean Sea.

The pressure gradient between a 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 the upcoming weekend. 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 Mon night.

ATLANTIC OCEAN...

Two cold fronts are to the north of 31N from 70W westward.
Precipitation: scattered to numerous strong is from 30N northward
between 64W and 66W. Widely scattered moderate to isolated strong
is from 26N to 30N between 66W and 72W, and from 30N northward
between 73W and 77W. Fresh to strong winds are from 28N northward
from 60W westward. The sea heights range from 3 feet to 5 feet
from 20N northward from 60W westward.

An upper level cyclonic circulation center is near 20N51W.
Comparatively drier air in subsidence is apparent in water vapor
imagery from the cyclonic center, southwestward beyond the islands
of the eastern Caribbean Sea. Upper level cyclonic wind flow
covers the Atlantic Ocean from 15N northward between 40W and 60W.
Precipitation: isolated moderate is from 20N northward between
40W and 64W, and elsewhere within a 360 nm radius of the 20N51W
upper level cyclonic center.

The sea heights range from 8 feet to 12 feet from 10N northward
between 20W and 50W. the surface trough. Strong to near gale-
force winds are from 13N to 30N between 20W and 30W, and from 10N
to 30N between 30W and 40W. Fresh to strong winds are from 19N to
25N between 45W and 54W. Moderate to fresh winds are in the
remainder of the area from 60W eastward.

Broad upper level cyclonic wind flow, and comparatively drier
air in subsidence that is apparent in water vapor imagery, cover
the area from 20N northward from 32W eastward. Precipitation:
rainshowers are possible in the areas of the upper level cyclonic
wind flow.

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/.

A cold front located off NE Florida 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.

$$
mt/gr
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