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Atlantic Tropical Weather Discussion



000
AXNT20 KNHC 091001
TWDAT 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 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 0600 UTC surface analysis and satellite imagery through 
1000 UTC.

...SPECIAL FEATURES... 

East Atlantic Gale Warning: A strong high pressure of 1036 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 10-13 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 Liberia near 06N10W to 04N30W to the 
coast of Brazil near 02N50W. Scattered moderate to isolated 
strong convection is noted from 03N-08N between 24W-44W.

GULF OF MEXICO...

A weak cold front extends from central Florida to 27N89W where it
transitions to a stationary front to 27N93W. Mainly low level 
clouds, with possible showers, are associated with the frontal 
boundary. Gentle to moderate E winds are noted behind the front
per scatterometer data. There is also an area of moderate E winds
just N of the Yucatan Peninsula. Light to gentle winds dominate 
the remainder of the Gulf. Sea heights are generally below 3 ft 
except just W of the Yucatan Peninsula and in the Yucatan Channel.

For the forecast, the aforementioned cold front will dissipate 
today. 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. Fresh to strong northerly winds 
and building seas are expected in the wake of the front through 
Sat night. 

CARIBBEAN SEA...

Satellite derived wind data provide observations of fresh to strong
trade winds in the south-central Caribbean, and in the Gulf of 
Venezuela. Moderate to fresh trades dominate the E basin as well 
as the SW Caribbean and Gulf of Honduras, with gentle E winds 
elsewhere in the NW Caribbean. Seas are 8 to 10 ft in the south- 
central Caribbean, with highest seas near the coast of Colombia, 
5-7 ft in the central and eastern basin, and 3 to 5 ft in the NW 
Caribbean, except in the lee of Cuba where seas of 1-3 ft are 
noted. The trades will continue to carry isolated to scattered 
passing showers.

For the forecast, the pressure gradient between a ridge across 
the northern Caribbean Sea and the Colombian/Panamanian low will 
continue to support fresh to strong trade winds 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 NE winds will develop in the Windward Passage, the
lee of Cuba and S of Hispaniola through Mon night. 

ATLANTIC OCEAN...

A cold front extends from 31N75W to central Florida. Scattered
showers are near the front. Farther E, a band of showers and
thunderstorms is ahead of a surface trough that extends from
near Bermuda to 27N72W. Fresh S to SW winds are observed on 
either side of the trough axis, particularly N of 29N between 63W 
and 69W. Fresh to locally strong northerly winds follow the front.
Elsewhere W of 65W, gentle to moderate winds are noted N of 27N 
and S of 22N, with light and variable winds from 22N to 27N where 
a ridge axis is present. Seas of 3-5 ft prevail N and E of the 
Bahamas, building to 5-7 ft N of 30N E of 77W.

For the forecast west of 65W, the above mentioned cold front 
will move across the northern forecast waters through tonight 
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 through Sat 
night. Another cold front will move off NE Florida on Sun, and 
reach from 31N65W to South florida by Sun night. The front is 
forecast to dissipate over the SE waters on Mon. High pressure 
behind the front will likely bring fresh to strong NE to E winds 
mainly across the waters S of 27N by Mon night into Tue.

Refer to the special features section above for details on the 
Gale Warning in the east Atlantic. Strong high pressure of 1036
mb located over the Azores extends a ridge over the remainder of 
the Atlantic forecast waters. The pressure gradient between this 
system and lower pressures in the vicinity of the ITCZ, continues 
to support fresh to strong trade winds and seas of 8-11 ft mainly 
across the region N of 10N and E of 50W. Seas of 7-8 ft in NE 
swell continue to propagate across the waters E of the Lesser
Antilles. This will gradually subside today.

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.

$$
GR