[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211805
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Tue Dec 21 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
1630 UTC.

...SPECIAL FEATURES...

.GULF OF MEXICO GALE WARNING...

A strong frontal low pressure system of 1001 mb located near
Tampa, Florida will sustain N to NE near-gale to gale winds off
the Florida W coast just S of the Big Band Area through late this
afternoon. Seas across the NE Gulf range from 8 to 10 ft. As it
moves northeastward across the Florida Peninsula and exits into
the Atlantic Ocean this evening, both winds and seas should
gradually subside across the NE Gulf. Please refer to the latest
High Seas Forecast, issued by the National Hurricane Centered the
following website:
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml, for more details.

.ATLANTIC GALE WARNING...

The aforementioned low pressure is going to exit into the
Atlantic off NE Florida this evening. This will cause SE to SW
winds to increase offshore from the Florida-Georgia coast,
reaching strong to near-gale with frequent gusts to gale force.
Sustained winds should increase to between near-gale and gale
later tonight. Seas will build to between 8 and 10 ft by this
evening and then peak at 10 to 13 ft through Wed morning. Please
refer to the latest High Seas Forecast issued by the National
Hurricane Center, at the following website:
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml, for more details.

...MONSOON TROUGH/ITCZ...

An ITCZ meanders west-northwestward from SW of the Liberia coast
at 03N14W to 05N41W to near Trinidad and Tobago. Scattered
moderate convection is found up to 150 nm from either side of the
ITCZ.

The E Pacific monsoon trough is triggering scattered showers and
isolated thunderstorms over Panama and nearby Caribbean waters.

...GULF OF MEXICO...

Please see the Special Features section above for details on gales
and high seas over the NE Gulf.

A cold front extends southwestward from a strong 1001 mb low
pressure near Tampa, Florida to the Yucatan Peninsula near the
Mexico- Belize border. Scattered showers and thunderstorms are
occurring along and up to 180 nm SE of the front, including the
Yucatan Channel, Florida Keys and Straits of Florida. Moderate to
fresh with locally strong SW to NW winds and seas at 7 to 9 ft are
present near the front. A surface trough runs westward from the
same low to the N central Gulf. Scattered showers are seen across
the N central and NE Gulf. Farther west, a 1021 mb high near
Tampico, Mexico is dominating the W edge of the Gulf with moderate
winds and seas of 5 to 7 ft. Tight pressure gradient between this
high and the strong low near Tampa, Florida is generating fresh
to strong northerly winds with seas of 6 to 9 ft across the NW and
central Gulf.

For the forecast, the aforementioned low will track NE and move
inland into Florida by early this afternoon. Gales will end for
the NE Gulf late this afternoon. Showers and some strong
thunderstorms will continue to be possible over the far SE Gulf
and Florida Straits before the front moves SE of the area this
evening. Fresh to strong winds and seas of 8 to 10 ft behind the
front will gradually subside late tonight and early Wed. High
pressure crossing the northern Gulf will lead to tranquil
conditions Wed night through Thu, but by Fri and into the weekend,
fresh to possibly locally strong S return flow will develop in
the western Gulf.

...CARIBBEAN SEA...

A cold front extends southwestward from the Yucatan Channel to the
Mexico-Belize border. Scattered showers and isolated thunderstorms
are evident across the NW edge of the Caribbean Sea, including
the Mexico-Belize coast. A surface trough embedded with the
trades is producing scattered showers and isolated thunderstorms
over the N Leeward Islands and Virgin Islands. Refer to the
Monsoon Trough/ITCZ section for additional weather in the basin.
Moderate to fresh ENE trades and seas at 5 to 7 ft are found over
the S central basin. Moderate to locally fresh SE to SW winds with
seas at 2 to 4 ft are occurring near the cold front. Gentle to
moderate ENE trades and seas of 4 to 5 ft prevail for the
remainder of the basin.

For the forecast, the cold front will gradually stall from the
Windward Passage to offshore Nicaragua for the latter part the
week. Fresh N winds can be expected behind the front. Elsewhere,
moderate to fresh trades will prevail over the central and E basin
through tonight. A weakening pressure gradient will lead to less
wind Wed and Thu. For tropical Atlantic waters E of the Lesser
Antilles, fresh to strong trades and large N to NE swell will
prevail into tonight.

...ATLANTIC OCEAN...

Please see Special Features section above for information on gales
that will develop offshore from the Florida-Georgia coast this
evening through Wed morning.

A frontal boundary runs northeastward from a strong 1001 mb low
near Tampa, Florida to a 1007 mb low offshore from Jacksonville,
Florida. This boundary then turns eastward across the Atlantic to
28N70W before turning east-northeastward to beyond 31N45W.
Scattered to numerous showers and thunderstorms are seen over
Florida and N of 27N between 74W and the Florida-Georgia coast.
Scattered showers are found farther E near the boundary, N of 28N
between 40W and 74W. The southwestern end of a cold front is
triggering scattered showers over the Canary Islands. A broad
surface trough along the Mauritania-Senegal coast is producing
scattered showers and isolated thunderstorms along the central
African coast and near the Cabo Verde Islands.

N of 28N, moderate to fresh winds are present near both frontal
boundaries N of 28N between the Canary Islands and 70W. While seas
at 7 to 10 ft dominate the first boundary between 40W and 70W, and
10 to 14 ft near the second boundary between the Canary Islands
and 40W. Moderate SE winds and seas at 6 to 9 ft are noted from
the Bahamas westward to the central and S Florida coast. The large
Mid-Atlantic ridge is providing light to gentle winds with seas at
5 to 7 ft from 21N to 28N between the NW African coast and 70W.
Moderate to fresh NE to ENE trades and seas of 7 to 9 ft prevail
across the rest of the Atlantic Basin.

For the forecast, the 1001 mb low pressure is crossing Florida
and will move into the Atlantic, east of northern Florida by late
this afternoon. The low will then move NE to the north of the
area tonight, with gale force winds developing on both sides of it
for areas N of 28N and W of 71W. Frequent gusts to gale force are
first expected east of Florida this afternoon. A trailing cold
front will cross the region Wed through Thu, bringing scattered
showers and thunderstorms with it. Building high pressure behind
the low should lead toward tranquil conditions Thu night through
Fri.

$$

Chan
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