[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 070951
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Tue Dec 7 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 is over the African continent. The ITCZ extends
from the coast of Sierra Leone near 08N13W to 04N30W to the coast
of Brazil near 02N50W. Scattered moderate isolated strong convection
is noted from 02N-06N between 25W-35W.

GULF OF MEXICO...

A ridge extends across Florida into the eastern Gulf of Mexico
where a 1018 mb high pressure is located near 26N86W. A stationary
front stretches from the Florida Panhandle to near Brownsville,
Texas. Moderate to fresh N to NE winds follow the front. Light to
gentle winds are noted elsewhere across the Gulf region per
satellite derived wind data. Seas are 4-6 ft over the NW Gulf and
W of the front while seas of 1-3 ft dominate the remainder of the
basin. Some cloudiness, with possible showers, in association with
the frontal boundary, is observed from southern Texas all the way
to SE Georgia and the Carolinas. A dense fog advisory is in
effect across the coastal waters of western Florida from near
Ft. Myers to the Florida Big Bend through mid-morning. Visibility
will frequently be reduced to less than one quarter mile or less.

For the forecast, the aforementioned stationary front extending
from the Florida Panhandle to near Brownsville, Texas will retreat
inland by 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 a strong cold
front forecast to push off the Texas coast by Sat morning.
Increasing winds and building seas are expected in the wake of the
front. Looking ahead, gale conditions are possible behind the
front during the upcoming weekend.

CARIBBEAN SEA...

The most recent scatterometer data provide observations of fresh
to strong winds over the south-central Caribbean, and in the Gulf
of Venezuela, where several wind barbs of 25-30 kt are noted.
Moderate to fresh trade winds prevail across the remainder of the
E and central Caribbean, particularly from 11N-18N and E of 80W.
Elsewhere, gentle to moderate winds are blowing. Seas in the 8-10
ft range are over the central Caribbean, with the highest seas
near the coast of Colombia. Seas of 6-8 ft dominate the remainder
of the east and central Caribbean. Seas of 4-6 ft can be found in
the NW Caribbean, except in the lee of Cuba, and the Yucatan
Channel. Shallow moisture embedded in the trade wind flow will
continue to move across the region 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. By Thu night into Fri, as high
pressure strengthens over the western Atlantic, expect fresh to
locally strong NE winds in the Windward Passage, and in the lee of
Cuba. This will persist through Sat while extending eastward
toward Hispaniola and Puerto Rico.

ATLANTIC OCEAN...

A surface ridge extends from Bermuda to the Bahamas. Gentle to
moderate winds are noted under the influence of this system with
the exception of moderate to fresh winds just N of Hispaniola.
Seas are in the 5-7 ft range E of the Bahamas based on buoy
observations and an altimeter pass. Seas of 3-5 ft prevail
elsewhere N of 27N. An area of showers and thunderstorms extends
from the NW Bahamas to near 31N73W. A diffluent pattern aloft
supports this convective activity.

For the forecast west of 65W, a ridge will prevail along 26N-27N
through late this week. Moderate to fresh NE to E winds are
expected along the southern periphery of the ridge, especially
south of 22N, including the waters just N of Hispaniola and
approaches to the Windward Passage. A weak cold front will stall
over the far northern waters today, then lift northward by
tonight. Another cold front will move over the northern forecast
waters Thu and Fri while dissipating.

The remainder of the Atlantic forecast waters is under the influence
of a 1036 mb high pressure located well N of area near 42N43W. A
surface trough is along 55W/56W from 21N-30N. Isolated showers
are near the trough axis. An upper-level low spinning W of the
Canary Islands is generating some shower activity over the
islands and regional waters. Fresh to located strong trade winds
and seas of 8-10 ft are observed over the Atlantic, mainly N of
10N and E of 50W due to the pressure gradient between the strong
high pressure to the N and lower pressures in the vicinity of the
ITCZ.

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
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