[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170539
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Thu Dec 17 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 0000 UTC surface analysis and satellite imagery through
0510 UTC.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal border areas of
Sierra Leone near 08N12W, TO 05N14W, to 05N16W. The ITCZ
continues from 05N16W, to 05N26W, to the Equator along 34W, to
01S41W. Precipitation: scattered to numerous strong is within
135 nm of the coasts of Sierra Leone and Liberia from 05N to
09N, within 150 nm to the north of the ITCZ between 19W and 26W,
from 03N to 04N between 18W and 19W, and from 04N to 05N between
30W and 31W. Widely scattered moderate to isolated strong, in
general, is elsewhere from 11N southward between 30W and 60W.

GULF OF MEXICO...

Upper level SW wind flow spans the entire Gulf of Mexico.

A 1010 mb low pressure center is in the Florida Big Bend near
30N84W. A cold front extends to the southwest of the low
pressure center, to 26N85W and 23N90W. The front becomes
stationary at 23N90W, and it curves to the northern part of the
Isthmus of Tehuantepec of southern Mexico. The earlier
gale-force wind speeds, that were near the coastal waters of
Veracruz in Mexico, have decreased to less than gale-force.
Precipitation: broken to overcast multilayered clouds and
isolated moderate rainshowers are to the south of the line that
runs from 29N at the Florida west coast, to 26N90W, to the coast
of Mexico at 24N; in Florida from 26N to 30N; and in the
Atlantic Ocean to the north of the line that runs from the
Florida east coast at 26N beyond 32N64W. Isolated moderate to
locally strong is in the NW corner of the Caribbean Sea, and in
the Yucatan Peninsula, from 16N to 21.5N between 86W and 91W.

The current cold front extends from A 1011 mb low pressure
center that is near 30N84.5W, to 25N86W to the central Bay of
Campeche near 18.5N93.5W. The winds that are behind the front
remain strong S of 24N, but they have diminished to less than
gale-force. The winds and the seas in the Gulf of Mexico will
diminish gradually through Friday, as high pressure builds
across the northern Gulf and the front sinks SE of the basin.
The next cold front will move into the northwest Gulf of Mexico
by Saturday evening, and move slowly SE, through Monday.

CARIBBEAN SEA...

Broad upper level anticyclonic wind flow, with a ridge, spans
the Caribbean Sea.

A cold front/stationary front is in the Gulf of Mexico. The SW
part of the frontal boundary is in the SW corner of the Gulf of
Mexico. Precipitation: isolated moderate to locally strong is in
the NW corner of the Caribbean Sea, and in the Yucatan
Peninsula, from 16N to 21.5N between 86W and 91W.

Rainshowers are possible, in scattered to broken low level
clouds that are moving through the area, from 70W eastward, and
from 14N northward from 70W westward.

The monsoon trough is along 08N/11N from 73W in N Colombia,
beyond Panama and Costa Rica. Precipitation: isolated moderate
is elsewhere from 14N southward from 73W westward to the coasts
of the countries of Central America.

Weak high pressure, to the north of the area, is supporting
moderate to fresh winds in the central Caribbean Sea. High
pressure will begin to strengthen to the north of the area, from
tonight through Thursday. The trade winds will be freshened
across most of the basin. The wind speeds near Colombia will
pulse to strong each night, through Saturday night. A weakening
cold front will move slowly SE across the Yucatan Channel and
the NW Caribbean Sea, from Thursday evening through Friday,
before dissipating. Strong high pressure to the north of the
front will produce fresh to strong NE trade winds across much of
the area, on Friday and Saturday, before diminishing modestly on
Sunday and Monday.

ATLANTIC OCEAN...

A 1010 mb low pressure center is in the Florida Big Bend near
30N84W. A cold front extends to the southwest of the low
pressure center, to 26N85W and 23N90W. The front becomes
stationary at 23N90W, and it curves to the northern part of the
Isthmus of Tehuantepec of southern Mexico. Precipitation: broken
to overcast multilayered clouds and isolated moderate
rainshowers are: in Florida from 26N to 30N; and in the Atlantic
Ocean to the north of the line that runs from the Florida east
coast at 26N beyond 32N64W.

An upper level trough is along 30N50W, to the NE corner of the
Caribbean Sea near 16N62W. A surface trough is along 29N55W
23N60W, to 17N64W in the NE part of the Caribbean Sea.
Precipitation: isolated moderate to locally strong is from 21N
to 30N between 41W and 54W. Isolated moderate rainshowers are
within 400 nm to the NW of the surface trough.

A 1028 mb high pressure center is near 31N31W. Surface
anticyclonic wind flow covers the Atlantic Ocean from 10N
northward from the 29N55W 17N64W surface trough eastward.

A cold front currently is exiting the SE U.S. coast. The cold
front will slide slowly SE, and reach from near Bermuda through
the central Bahamas to central Cuba, late on Friday morning.
Expect fresh to strong southwesterly winds, ahead of the front,
N of 28N, from tonight through Thursday. The front will weaken
gradually, and become E-to-W aligned along 24N, on Sunday.

$$
mt/ss
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