[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191053
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Tue Dec 19 2023

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 0600 UTC surface analysis and satellite imagery through
1030 UTC.

..SPECIAL FEATURES...

Large Area of Seas in Excess of 12 feet across the Western
Atlantic:
A cold front has stalled overnight across the W Atlantic, and
remains from near 31N69W southwestward through the Windward
Passage. A strong 1050 mb high pressure system near 45N42W extends
southwestward to Hispaniola. The pressure gradient between these
features was supporting near-gale to gale force winds N of 26W and
between 61W and the front overnight. However, winds have
diminished slightly, to below gale-force in the past few hours.
Seas generated by strong to gale-force winds to the S and SW of
the strong high have produce an expansive area of seas 12 ft and
greater across the Atlantic in recent days. Seas of 12 to 16 ft in
merging E and S swell, and associated with the recent gale- force
winds, cover the waters N of 26N between 61W and 75W. Strong high
pressure will build into the western Atlantic behind the front
today through early Thu, and force the front to move SE. This will
also to produce fresh to strong N to NE winds behind the front,
gradually diminishing to moderate to fresh Thu through Fri. Seas
will subside very slowly to the W of 60W through Tue night as
large NE to E swell continues to move into this area. This swell
will then begin to mix with northerly wind swell being generated
behind the front to produce an increasing trend in seas W of 60W,
with seas again building to 12 to 15 ft to the N of 21 between 65W
and the Bahamas by Wed night.

Central Atlantic Gale Warning:
The pressure gradient between the aforementioned 1050 mb high
centered near 45N42W and a stationary front extending from 31N34W
to 23N56W is supporting a large area of near-gale to gale force
winds N of 24N between 43W and 57W. Seas over this area are
peaking at 23 ft near 28N50W. Seas greater than 12 ft in NE swell
cover the waters N of 20N and between 35W and 65W. The strong high
center will move northeastward over the next couple of days,
while the stationary front weakens. This will loosen the pressure
gradient, and diminish winds below gale force by late this
afternoon. However, large NE swell will continue to produce an
expansive area of seas 12 ft and greater through Wed morning,
before gradually diminishing to less than 12 ft across the area E
of 65W, by Thu morning.

Please read the latest NWS High Seas and Offshore Waters
Forecasts issued by the National Hurricane Center at
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and
https://www.nhc.noaa.gov/marine/offshores.php for more details on
both Gale Warnings.

...MONSOON TROUGH/ITCZ...

The monsoon trough reaches the Atlantic through the coast of
Liberia near 06N10W and continues westward to 05.5N14W. The ITCZ
extends from 05.5N14W to 02N50W. Scattered moderate isolated
strong convection is observed from 02.5N to 10.5N between 20W and
33W.

...GULF OF MEXICO...

A 1024 mb high pressure system positioned near the southern Texas
coast is allowing for dry, continental air to filter across the
Gulf of Mexico. No deep convection is noted in the basin.
Overnight scatterometer satellite data showed moderate to fresh
northerly winds over the eastern half of the Gulf of Mexico. Seas
in these waters are 4-7 ft. Elsewhere, light to gentle winds and
slight to moderate seas prevail.

For the forecast, stronger high pressure will shift eastward
across the central U.S. and into the eastern U.S. through Thu, to
produce fresh to strong NE to E winds across the eastern Gulf,
including the Straits of Florida, through early Fri. SE return
flow is expected to develop Sat.

...CARIBBEAN SEA...

A stationary front extends from the entrance of the Windward
Passage to near 10N77W. Scattered showers are seen on satellite
imagery near this boundary, with a few clusters of moderate
thunderstorms across Hispaniola. No deep convection is evident in
the remainder of the Caribbean Sea.

The pressure gradient between the aforementioned front and the
ridge over the Gulf of Mexico sustains fresh to strong northerly
winds west of 77W. The strongest winds are found within 120 nm of
the coast of Nicaragua and NE Honduras. Seas are 7-10 ft south of
18N and between 77W and 85W and 4-7 ft in the rest of the
Caribbean waters west of 77W. The highest seas are found in the SW
Caribbean near 11N81W. In the remainder of the basin, moderate or
weaker winds and moderate seas are prevalent.

For the forecast, high pressure will build SE across the western
Atlantic Tue night through Fri. This will force the N portion of
the front to drift SE across Hispaniola Tue and Wed before
gradually dissipating Wed night. Fresh to strong N winds behind
the front, along about 77W, will become N to NE Tue night through
Wed then veer NE Wed night through Thu night, with strongest
winds in the lee of Cuba and through the Windward Passage. At the
same time, fresh trades are expected in the south-central
Caribbean, including the Gulf of Venezuela, increasing to strong
at night.

...ATLANTIC OCEAN...

Please read the Special Features section for more on the ongoing
Central Atlantic Gale Warning.

The W Atlantic cold front has stalled from near 31N69W southwestward
through the Windward Passage. Scattered moderate isolated strong
convection persists along and E of the front to 66W, from
Hispaniola to beyond 31N. Aside from the areas in the Special
Features section, the pressure gradient between the ridge over the
Gulf of Mexico and a frontal system off the eastern United States
sustains fresh to strong NW winds north of 27N and west of 76W.
Seas are 8 to 11 ft in merging NW and E swell in this area. Moderate
or weaker winds are found in the remaining waters west of the
cold front. Aside from the 12 ft or greater seas west of 70W, 8-12
ft are prevalent north of the Bahamas and east of Florida.

Outside of the area of gale force winds, fresh to near gale-force
mainly NE to E winds are N of 20N and between 35W and 62W. A deep
layered upper level cyclone across the central Atlantic is
supporting scattered moderate isolated strong convection from
14.5N to 23.5N between 40W and 48W. A 1009 mb low center is
underneath this upper cyclone, centered near 23N49.5W, and is
contributing to the pressure gradient and gale-force winds to the
north. Farther east, fresh to strong easterly winds are evident
east of 33W and north of 13N. Moderate or weaker winds are present
elsewhere in the basin. Aside from the area of 12 ft seas, NE to
N swell dominates the Atlantic, with seas greater than 8 ft
covering the waters N of 18N and W of 35W. Seas of 8-11 ft are N
of 20N and E of 35W. Elsewhere, seas of 5-8 ft prevail.

For the forecast W of 55W, strong high pressure will build
into the western Atlantic behind the front tonight through early
Thu to produce fresh to strong winds, gradually diminishing to
moderate to fresh Thu through Fri. This will force the front to
move SE and reach from 31N66W to Haiti Tue evening, from 31N61W to
central Hispaniola Wed evening, then begin to dissipate from
22N60W to NE Hispaniola Thu evening. Winds and seas will slowly
subside Fri through Sat as high pressure weakens.

$$
Stripling
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