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Atlantic Tropical Weather Discussion



000
AXNT20 KNHC 060947
TWDAT 

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Mon Dec 6 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 
0945 UTC.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean through the coast of
Sierra Leone, then continues SW to near 05N18W. The ITCZ extends
from 05N18W to 03N30W to the coast of Brazil near 02N50W.
Scattered moderate convection is noted from 02N-07N between 25W-
50W. Similar convection is from 03N-06N between 08W-12W.

GULF OF MEXICO...

A ridge extends across Florida into the Gulf of Mexico. Recent
scatterometer data indicate moderate to fresh southerly winds over
the western Gulf, particularly N of 22N and W of 92W while gentle
to moderate winds prevail elsewhere. Seas are 3-4 ft in association
with the strongest winds, and 1-3 ft elsewhere. Multilayered 
clouds, with possible showers, are observed over the NW and 
north-central Gulf. These clouds are the result of strong SW 
winds aloft.

For the forecast, a ridge will dominate most of the Gulf waters 
through Fri producing generally gentle to moderate anticyclonic 
flow. A weak cold front will reach the NW Gulf late today into the
evening hours. Fresh to locally strong northerly winds will 
follow the front forecast to stall before retreating inland Tue. 
The next cold front is forecast to move off the Texas coast on 
Sat. Moderate to fresh southerly return flow is expected over the 
NW and north-central Gulf ahead of the front Fri and Fri night. 

CARIBBEAN SEA...

Satellite derived wind data provide observations of fresh to
strong winds over the south-central Caribbean, and moderate to
fresh trade winds across the remainder of the E and central
Caribbean. A pair of altimeter passes indicate seas of 8-10 ft
over the south-central Caribbean where the strongest winds
prevail. Seas of 6-7 ft are noted elsewhere S of 18N and E of 
80W. Seas of 4-6 ft can be found in the NW Caribbean, except in 
the lee of Cuba, and in the Gulf of Honduras. Scattered showers 
and thunderstorms are near 20N85W just ahead of a short-wave 
trough that crosses the SE Gulf of Mexico into the Yucatan 
Channel. Moisture in this area is forecast to move westward while 
dissipating. Shallow moisture embedded in the trade wind flow is 
seen elsewhere across the basin producing isolated to scattered 
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. Moderate to locally fresh easterly 
winds are also forecast in the Gulf of Honduras beginning tonight.

ATLANTIC OCEAN...

A surface ridge extends from Bermuda to near the border of Georgia
and Florida. Gentle to moderate E to SE winds are noted across the
SW N Atlantic per scatterometer data. Seas are 2 to 4 ft north of
27N and west of 77W, and 4 to 6 ft elsewhere N of 27N and W of 
65W. Seas of 5 to 7 ft are S of 27N and E of the Bahamas. 

For the forecast west of 65W, a ridge will dominate most of the 
forecast waters through Fri. A weak cold front will push off NE 
Florida Tue before stalling and retreating northwest through Tue 
night. Another cold front will move across the north waters on Thu
while weakening. Moderate to fresh NE to E winds are expected
along the southern periphery of the ridge, especially south of 
22N, including approaches to the Windward Passage, through the 
week. 

Over the central Atlantic, a stationary front extends from a weak 
1022 mb low pressure located near 31N52W to 25N54W. Scattered to 
numerous showers and are ahead of the front affecting mainly the 
waters from 24N-30N between 48W- 51W. Fresh to strong NE winds and
seas of 7-9 ft are seen in the wake of the front. Farther E, a 
strong high pressure of 1036 mb remains in place over the Azores. 
Fresh to strong NE winds are blowing N of 23N and E of 32W, 
including the Canary Island. Moderate to fresh trades are observed
across much of the Atlantic N of the ITCZ and E of 50W. Seas of 
8-10 ft are within this area of winds. Moderate to fresh NE to E 
winds dominate the waters E of the Lesser Antilles with seas of 
6-9 ft based on altimeter data and buoy observations. An upper- 
level low situated W of the Canary Islands is generating some 
shower activity just S of the islands.

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 W of the volcano.

$$
GR