[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121702
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Fri Nov 12 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 1200 UTC surface analysis and satellite imagery through
1655 UTC.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coast of Senegal near 13N17W
to 08N23W. The ITCZ then continues from 08N23W to 05N38W to the
coast of French Guiana near 05N52W. Scattered moderate to isolated
strong convection is observed within 200 nm on both sides of the
ITCZ and monsoon trough E of 35W.

GULF OF MEXICO...

A weak cold front extends from the Big Bend region of Florida near
29N83W to the west-central Gulf of Mexico near 24N93W. A pre-
frontal trough extends across Florida and the Florida Keys to the
NW Caribbean Sea. Scattered moderate convection is noted near the
cold front and trough axis, mainly E of 88W. A recent
scatterometer satellite pass show fresh to strong winds in the
Florida Straits, likely associated with the strongest storms.
Moderate or weaker winds prevail in the rest of the Gulf. Seas of
1-3 ft are prevalent in the basin, with the highest seas occurring
in the NW Gulf.

For the forecast, the aforementioned cold front will stall over
the southeast Gulf tonight. A reinforcing front will enter the
basin late tonight followed by strong winds and seas to 8 ft over
the northwest and north-central Gulf. The front will sweep
through the basin Sat. By Sat night into Sun, high pressure will
build into the northern Gulf, and strengthen into Mon. This will
support fresh winds late this weekend into early next week across
portions of the northwest and southern Gulf, with strong E winds
possible over the Straits of Florida. The high pressure will shift
east of the region Tue.

CARIBBEAN SEA...

The main feature of interest in the Caribbean Sea is a surface
trough that extends from just W of the Cayman Islands near 19N83W
to Florida peninsula. A few showers are present to the E of the
trough axis. Satellite-derived wind data indicate that the storm
activity is producing fresh to strong winds. The rest of the
region is enjoying fairly tranquil weather conditions.

A modest pressure gradient due to a strong 1034 mb high pressure
over Nova Scotia and lower pressures in NW South America results
in fresh to locally strong trades in the south-central Caribbean,
with the strongest winds occurring within 90 nm of the coast of
NW Colombia. Fresh trades are also noticed in a recent
scatterometer satellite pass in the north-central and NE
Caribbean. Moderate or weaker trades are found elsewhere. Seas of
4-7 ft are present in the SW, central and E Caribbean Sea, with
the highest seas occurring offshore NW Colombia. The remainder of
the basin is experiencing 2-4 ft seas.

For the forecast, high pressure north of the area is supporting
moderate to fresh trade winds across most of the Caribbean. The
high will shift east later today, ahead of a cold front that will
stall over the Yucatan Channel Sat. A second front will move
through the Gulf Sun then stall from eastern Cuba to the Gulf of
Honduras by Sun night. Looking ahead, the front will shift
eastward into the Windward Passage into Tue as reinforcing high
pressure builds north of the area behind a third front moving
through the western Atlantic. This pattern will support fresh NE
winds across parts of the northwest Caribbean Mon and Tue.

ATLANTIC OCEAN...

A deep upper level trough continues to dig into the SE United
States, bringing a cold front that stretches from New England to
the west-central Gulf, crossing central Florida along the way. A
pre-frontal surface trough extends from Long Island to 31N77W and
crossing southern Florida on its way to the NW Caribbean. The
favorable upper level dynamics result in a large area of scattered
showers and isolated thunderstorms, mainly W of 73W, affecting
the NW and central Bahamas. The latest scatterometer satellite
pass depict fresh to locally strong southerly winds ahead of the
pre-frontal trough, likely associated with the storm activity.

Farther east, a cold front enters the tropical Atlantic near
31N38W and continues SW to 28N45W, becoming a stationary front
that then extends to near 22N65W, well north of Puerto Rico.
Scattered showers and isolated thunderstorms are noted near the
trough axis, mainly E of 44W. A dissipating cold front is barely
entering our region, extending from 31N47W to 29N57W. Satellite-
derived winds show that fresh to strong winds are occurring behind
the frontal boundaries, especially N of 22N and W of 42W, with
the strongest winds found behind the dissipating cold front.

Elsewhere, a weak surface trough extends from 19N-28N along 36W
and it is only producing a few shallow showers near the trough
axis. Moderate or weaker winds prevail in the rest of the basin.
Seas of 5-8 ft are found W of 60W. N swell produces 8-10 ft seas N
of 25N and between 35W and 58W. Seas of 4-7 ft are present in the
remainder of the tropical Atlantic.

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/.

For the forecast W of 65W, the previously-mentioned cold front
moving off the NE Florida coast will gradually slow and weaken,
and will reach from 31N74W to the Straits of Florida later today.
Another cold front will move off the northeast Florida coast late
Sat, then merge with first front by early Sun from 31N70W to
western Cuba. The merged fronts will stall from near 31N70W
through central Cuba by early Mon. Looking ahead, a third front
will move off the northeast Florida coast late Sun night,
eventually overtaking and merging with the stalled front, and then
will stall from 27N65W to the Windward Passage late Mon and Tue.

$$
DELGADO
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