[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201751
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sun Dec 20 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 1200 UTC surface analysis and satellite imagery through
1700 UTC.

...SPECIAL FEATURES...

West Atlantic Gale Warning: A cold front will move east of
northern Florida and into the west Atlantic early Monday morning
before sunrise. Low pressure will strengthen along the front
early Mon morning, resulting in strong to gale force winds,
mainly north of 27.5N and east of 80.5W. The low pressure will
move well north of the area later on Monday as the cold front
progresses quickly eastward. Expect strong to gale force SW winds
on Monday through early Monday evening, ahead of the cold front,
in the waters from 27.5N-31N between 65W-80.5W, as the front
moves E, with seas of 8-12 ft. By Monday night, winds will
diminish below gale force over the area. Please read the latest
High Seas Forecast at https://www.nhc.gov/text/MIAHSFAT2.shtml
for more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the border of Sierra Leone and
Guinea near 09N13W to 08N17W. The ITCZ is from 08N17W to 05N30W
to 05N42W to the coast of Brazil near 03N51W. Scattered moderate
and isolated strong convection is within 120 nm north and 90 nm
south of the ITCZ between 20W-46W.

GULF OF MEXICO...

As of 20/1500 UTC, a 1014 mb low is over the NE Gulf of Mexico
near 30N87.5W. A recent ASCAT pass shows strong wind speeds
within 120 nm of the low center in the southern semicircle, with
fresh winds elsewhere over the NE Gulf. A cold front extends SW
from the low to 23N93W to the coast of Mexico near 21N97W to
22N100W. A stationary front extends E from the low to the Florida
Big Bend near 30N83W. A pre-frontal trough, oriented NE-SW is
analyzed from 28N85W to 24N90W. Scattered moderate convection is
near the NE end of the pre-frontal trough from 26N-28.5N between
83W-86W. Scattered moderate convection is also noted within 30 nm
either side of a line from 25N89W to 22N95.5W. Scattered showers
are near the stationary front, over and to the south of the
Florida Panhandle. A surface trough is in the Bay of Campeche
along 93.5W, south of 21N, with scattered showers near it. High
pressure over east Texas is building in behind the front over the
NW Gulf, with dry, stable air.

As for the forecast: Fresh to strong gusty winds are expected
today with scattered showers and tstorms near the low and ahead
of the cold front over the eastern Gulf of Mexico. The front will
extend from southwest Florida to the Yucatan peninsula on Mon
morning, then exit the area by Mon night. On Thu, a strong cold
front will enter the basin and bring possible gale force winds in
the SW Gulf.

CARIBBEAN SEA...

Mid to upper-level anti-cyclonic flow covers the Caribbean Sea,
which is leading to relatively dry air and subsidence. However,
isolated showers in trade wind cumulus are possible south of
Haiti, near Jamaica and in the Gulf of Honduras. The latest ASCAT
data shows fresh trades across much of the eastern and central
basin. Moderate trades are seen over the area west of 81W.

As for the forecast: High pressure north of the area will support
moderate to fresh trade winds across much of the area. Highest
winds and seas will continue to be in the southern Caribbean,
near the coast of Colombia, pulsing at nighttime through Thursday
night. A cold front will slide southward into the NW Caribbean by
the end of the week enhancing winds and seas.

ATLANTIC OCEAN...

A cold front will emerge off the northern Florida coast and enter
the Atlantic early Mon morning, and reach from 31N65W to the
southern Bahamas Tue morning. Low pressure will strengthen along
the front Monday morning, resulting in strong to gale force winds
mainly north of 27.5N and east of 80.5W. See the Special Features
section above for more details on the Gale Warning. Scattered
showers and thunderstorms are expected in advance of and along
with the cold front late tonight through Monday. A few of the
thunderstorms could be strong. Expect strong to gale force SW
winds on Monday through early Monday evening, ahead of the cold
front, in the waters from 27N-31N between 65W-80.5W, as the front
moves E. Fresh to strong NW winds will prevail behind the front.

Currently, scattered showers are developing east of Florida, over
the west Atlantic. A surface trough is analyzed from 31N80W to
29N80.5W. Strong S winds are east of the trough from 29N-32N
between the trough and 77.5W. Moderate W winds are west of the
trough.

Farther east, a cold front extends over the central Atlantic from
32N41W to 26N54W, then continues as a stationary front to 23N65W.
The stationary front is currently dissipating from 23N65W to the
Turks and Caicos Islands. Scattered moderate convection is along
and within 60 nm ahead of the front, north of 28N and east of
41W. Isolated showers are elsewhere within 30 nm of the front.
Fresh NE winds are within 120 nm NW of the front between 55W and
the Turks and Caicos Islands. Strong SW winds are SE of the
front, north of 30N between 32W-41W. The stationary portion of
the front will dissipate today, while the cold front will
continue to push eastward and dissipate through the next 24-36
hours. Ridging covers the northeast part of the area, anchored by
a 1027 mb high pressure near 31N22W.

$$
Hagen
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