[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 052139
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sat Dec 5 2020

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 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through
2115 UTC.

...SPECIAL FEATURES...

Gulf of Mexico Gale Warning: An earlier scatterometer pass over
the western Gulf indicated a sharp surface trough from near
Brownsville Texas southeastward to near Ciudad del Carmen in the
Bay of Campeche. An area of low pressure is starting to form along
the trough, ahead of a mid/upper low moving into the southern
Plains. The scatterometer pass indicated fresh NW winds were
already in place over the far western Gulf. These winds are
expected to increase in that area as the low pressure deepens
through Sun. Ensemble probabilities indicate a high chance of
strong to near gale force winds south of 26N and west of 94W
through Sun, and a medium chance for winds briefly reaching
minimal gale force off Veracruz late Sun. Seas may reach as high
as 13 ft there as well. Winds and seas will diminish through Mon
as low rapidly lifts out to the east, and high pressure builds
over the northern Gulf.  Please, read the latest NWS High Seas
Forecast issued by the National Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.html for more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal sections of Sierra
Leone near 08N13W to 06N18W. The ITCZ continues from 06N18W to
to 09N37W to 07N42W, and from 06N48W to 03N52W. A surface trough
is from 12N44W to 00N47W. Scattered moderate convection is within
60 nm of the monsoon trough. Scattered moderate convection is
along the ITCZ from 08N- 14N between 25W-45W.

GULF OF MEXICO...

As of 05/1800 UTC, a cold front extends from near Naples, Florida
to the northern coast of the Yucatan Peninsula near Merida to the
Bay of Campeche near 20N92W. A 1014 mb surface low pressure area
was analyzed near 21N94W, along a trough reaching toward
Brownsville, Texas. Fresh to strong NW winds were noted west of
this trough on earlier scatterometer satellite data. A buoy near
the low pressure is showing seas to 7 ft, and it is likely seas
are at least 8 ft farther to the southwest in the area of fresh
to strong winds. Seas are 3 to 5 ft elsewhere over the western
Gulf of Mexico, and 2 to 4 ft over the eastern Gulf. Moist,
southerly flow in the mid and upper levels ahead of an approaching
mid/upper level trough is promoting a few light showers off
southwest Louisiana and the north Texas coast.

For the forecast, the developing low in the southwest Gulf will
support strong to near gale force winds over the far western Gulf
through Sun, briefly reaching gale force late Sun off Veracruz.
The low pressure will move rapidly toward the Carolina coast Sun
through Mon, dragging a reinforcing front across the eastern Gulf
Mon into Tue. Winds and seas diminish through mid week as the cold
front shifts southeast of the area and high pressure builds over
the northern Gulf. Looking ahead, southerly return flow will
increase over the northwest Gulf by Thu ahead of the next cold
front.

CARIBBEAN SEA...

An earlier scatterometer pass indicated fresh to occasionally
strong trade winds pulsing off Colombia, with moderate trades
elsewhere over the eastern and central Caribbean, with 5 to 7 ft
seas. Light to gentle winds are noted over northwest Caribbean,
with 2 to 4 ft seas. A few showers are noted over the northwest
Caribbean, with fair weather noted elsewhere.

For the forecast, the fresh to strong trades will continue to
pulse through Sun off Colombia, then diminish as high pressure
north of the area weakens and shifts east ahead of an approaching
cold front. The front will reach the Yucatan Channel Mon, extend
from western Cuba to eastern Honduras Tue, and stall from the
Windward Passage to northeast Nicaragua through mid week.

ATLANTIC OCEAN...

A cold front reaches from 31N73W to Vero Beach, Florida. A
scatterometer satellite pass from around 15 UTC indicated fresh to
strong SW winds within 120 nm east of the front north of 30N, and
seas are estimated to be near 8 ft in this area. A few showers are
likely ongoing within 300 nm of east the front as well, north of
28N. Light showers are also possible across the southern Bahamas.

For the forecast west of 65W, the cold front will start to stall
and weaken from Bermuda to the Upper Florida Keys by early Sun.
The front will lift northward through late Sun ahead of a stronger
cold moving off the northeast Florida coast late Sun night. The
second front will reach from Bermuda to western Cuba Tue, and from
25N65W to the Windward Passage through mid week. Winds to gale
force are possible ahead of the front N of 29N and E of 70W Mon
night into Tue.

Farther east, a few showers and thunderstorms are noted within 120
nm either side of a trough reaching from 32N53W to 15N45W, with
gentle winds and moderate seas north of 20N between 50W and 65W.
A broad area of fresh to strong trade winds and associated swell
in excess of 8 ft is noted north of 20N and east of 50W, with an
altimeter satellite pass indicated seas to near 12 ft off the Cabo
Verde Islands. Moderate trade winds and 5 to 8 ft seas are noted
elsewhere south of 20N.

$$
Christensen
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