[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 080951
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Wed Dec 8 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 remains inland in Africa. The ITCZ extends
from the coastal plains of Sierra Leone near 08N13W to 03N30W
to the coast of Brazil near 02N50W. Scattered moderate isolated
strong convection is noted from 03N-07N between 20W-31W, and from
04N-07N between 41W-45W.

GULF OF MEXICO...

The stationary front previously located over the northern Gulf
has move inland, and now extends from SE Georgia to eastern Texas.
A 1019 mb high pressure is centered near Tampa Bay, Florida and
extends a ridge across most of the Gulf region. Light to gentle
winds are noted across the basin per satellite derived wind data.
Seas are 1-3 ft throughout. A small are of showers and thunderstorms
is near 25N86W. A dense fog advisory remains in effect across the
coastal waters of western Florida from near Sarasota to the Florida
Big Bend, and from the Florida Big Bend to SE Louisiana through
mid-morning. Visibility will frequently be reduced to one quarter
mile or less.

For the forecast, reinforcing high pressure north of area will
allow the aforementioned stationary front to move SE as a cold
front over the N waters today before dissipating 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. Frequent gusts to gale force
are possible behind the front.

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. Moderate to fresh trade winds prevail across the
remainder of the E and central Caribbean, particularly from 10N-
18N and E of 80W. Elsewhere, gentle to moderate winds are blowing.
Seas are 8-11 ft over the south-central Caribbean per a recent
altimeter pass. Seas of 6-8 ft dominate the remainder of the east
and central Caribbean with seas of 4-6 ft in the NW Caribbean,
except in the lee of Cuba, and the Yucatan Channel where mainly
seas of 1-3 ft prevail. Shallow moisture embedded in the trade
wind flow will continue to move across the region producing
isolated to scattered passing showers. Transverse high clouds are
noted over the eastern Caribbean through the Lesser Antilles into
the tropical Atlantic due to strong westerly winds aloft.

For the forecast, 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 Fri night. Moderate
to fresh trades will prevail elsewhere except in the NW Caribbean
where mainly gentle to moderate winds are expected. As high
pressure strengthens over the western Atlantic, expect fresh to
locally strong NE winds in the Windward Passage, the lee of Cuba
and south of Hispaniola Thu night through Sun.

ATLANTIC OCEAN...

A surface trough is analyzed from 31N73W to the NW Bahamas. A few
showers are ahead of the trough axis mainly N of 27N. Recent
scatterometer data indicate moderate to fresh SE winds N of 28N
and E of the trough to about 70W. Elsewhere W of 65W, gentle to
moderate winds prevail. Seas are 3-5 ft N and E of the Bahamas.

For the forecast west of 65W, reinforcing high pressure over the
eastern of US will push a cold front off NE Florida by this
evening. The front 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.

The remainder of the Atlantic remains under the influence of a
strong 1035 mb high pressure located just W of the Azores near
38N30W. A surface trough is along 59W/60W from 19N-30N. An area
of scattered showers and isolated thunderstorms is over the
central Atlantic affecting roughly the waters from 21N-28N
between 48W-54W. This convective activity is at leading edge of an
area of fresh to strong NE-E winds around the southern periphery
of the Azores high. Seas of 8-10 ft are noted per altimeter data
within these winds. Fresh to locally strong trade winds are
observed over the remainder of the Atlantic, but mainly N of 10N
and E of 50W due to the pressure gradient between the above
mentioned Azores high 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 in the vicinity of
the volcano.

$$
GR
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