[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170427
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Wed Nov 17 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 0000 UTC surface analysis and satellite imagery through
0415 UTC.

...MONSOON TROUGH/ITCZ...

The monsoon trough remains mainly inland over Africa, reaching the
Atlantic through the coast of Guinea near 12N16W to 09N19W. The
ITCZ extends from 09N19W to 09N30W, then resumes west of a
surface trough from 05N36W to 04N45W. The surface trough extends
from 10N31W to 03N35W. Scattered moderate and isolated strong
convection is noted from 01N to 13N and between 21W and 41W.

GULF OF MEXICO...

The influence of a 1026 mb high pressure system located between
the Outer Banks and Bermuda extends into the Gulf of Mexico. A dry
continental airmass continues to dominate the region, maintaining
tranquil weather conditions. Fresh E-NE winds are present in the
SE Gulf waters, including the Florida Straits, and in the NW Gulf,
especially within 100 nm of southern Texas. Seas of 4-6 ft are
occurring in the SE Gulf, including the Florida Straits, and NW
Gulf. Moderate or weaker winds and 1-3 ft seas prevail elsewhere.

For the forecast, strengthening high pressure has moved E into the
Atlantic, leaving fresh E winds over the SE Gulf and Florida
Straights into Thu. A cold front will move through the Gulf Thu
night and Fri. Fresh to strong northerly winds and building seas
will follow the front. Scattered showers and isolated
thunderstorms are expected ahead of this front.

CARIBBEAN SEA...

A surface trough extends from central Cuba to just west of Swan
Island near 18N85W. Another surface trough extends across the
Gulf of Honduras from the Yucatan peninsula to E Honduras. Plenty
tropical moisture associated with these boundaries and divergence
aloft results in a large area of showers and isolated
thunderstorms, mainly W of 80W and N of 14N. A few showers are
also noted in the SW Caribbean Sea between SE Nicaragua and N
Panama, likely enhanced by the eastern portion of the Pacific
monsoon trough that enters the Caribbean near SE Costa Rica. Dry
air dominates the rest of the basin, allowing for tranquil weather
conditions.

The pressure gradient between the 1026 mb high pressure system in
the W Atlantic and lower pressures over South America allows fresh
to strong trades to prevail across the south-central Caribbean
Sea, with the strongest winds occurring off NW Colombia. A recent
scatterometer satellite pass also detected a small area of near-
gale trades within 90 nm of the Guajira peninsula of Colombia.
Fresh trades are also noted in the north-central and NE Caribbean
and N of 19N in the NW Caribbean. Seas of 6-9 ft are prevalent in
the central, SW and E Caribbean Sea, with the highest seas
occurring off NW Colombia. Seas of 3-6 ft are present elsewhere.

For the forecast, a remnant stationary front has devolved into a
trough that stretches from central Cuba to E of Belize. This
trough will dissipate later tonight, and high pressure will
strengthen and build south through the basin. Combined with lower
pressure over South America, the pressure gradient will increase,
thus winds will increase, to strong over portions of the central
Carribbean and passages off the Greater Antilles through Thu. A
cold front is forecast to approach the Yucatan Channel Fri.

ATLANTIC OCEAN...

A cold front enters the tropical Atlantic near 31N57W and extends
to 27N67W, where it transitions into a dissipating stationary
front that continues to the central Bahamas, where it becomes a
surface trough that continues into the NW Caribbean Sea. Only a
few showers are observed near the trough axis. A recent
scatterometer satellite pass show fresh to strong NE winds within
200 nm to the north of the frontal boundary and trough axis, with
the highest winds occurring S of 26N and W of 76W. A weak surface
trough extends from 29N58W to 22N60W and no deep convection is
present near the trough axis.

Farther east, a 1013 mb low pressure is near 28N33W. A weakening surface
trough associated with the low pressure extends from 30N30W to
26N28W to 20N41W. Scattered moderate convection is noted N of 26N
and between 25W and 31W. The latest scatterometer satellite data
indicate that fresh to strong cyclonic winds are present N of 26N
and between 25W and 42W. Another surface trough extends from
15N46W to 09N49W and a few showers are seen on satellite imagery
within 200 nm of the trough axis. The rest of the basin enjoys
fairly tranquil weather conditions.

Satellite-derived wind data depict fresh to strong NE winds off
Western Sahara, mainly from 25N to 29N and E of 17W. Moderate or
weaker winds prevail elsewhere in the basin. Seas of 4-8 ft are
found W of 60W, while 6-10 ft seas are prevalent elsewhere in the
tropical Atlantic. Peak seas of 10 ft are noted well NW and SW of
the Cabo Verde Islands, near 26N38W and 11N32W, respectively.

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, the aforementioned cold front will continue to
move east, and the stationary front will dissipate through Wed as
high pressure builds over the western Atlantic. This will lead to
increasing E winds and building seas S of about 28N Wed night
through Thu night. Looking ahead, a cold front will move offshore
NE Florida Thu night, then stall from Bermuda to central Cuba over
the weekend. This front will be followed by fresh to strong
northeast to east winds and building seas north and northeast of
the Bahamas.

$$
DELGADO
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