AXNT20 KNHC 091001
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
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.
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
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
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.
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