[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200525
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Wed Dec 20 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 0000 UTC surface analysis and satellite imagery through
0505 UTC.

..SPECIAL FEATURES...

Central Atlantic Significant Swell Event:
A surface trough stretches from 17N55W to 26N60W. Meanwhile, a
robust high pressure system of 1053 mb is positioned near 47N31W.
The pressure gradient between these features is supporting fresh
to near gale-force easterly winds north of 25N and between 41W and
61W. Seas of 12-20 ft are present north of 21N and between 30W and
65W. The highest seas are occurring near 31N54W. The ridge will
slide eastward and weaken in the next couple of days, allowing the
winds to diminish and seas to subside, decreasing below 12 ft Thu.

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
the Gale Warning and Very Rough Seas.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic through the coast of
Liberia near 07N11W and continues to 05N14W. The ITCZ stretches
from 05N14W to 02N33W to 03N51W. No deep convection is noted near
the ITCZ.

...GULF OF MEXICO...

An expansive 1032 mb high pressure system over the eastern United
States extends southwestward, encompassing the Gulf of Mexico. No
deep convection is noted across the basin. Fresh to strong NE
winds are found in the SE Gulf and Florida Straits. Seas in these
waters are 5-7 ft. Moderate to locally fresh easterly winds and
seas of 4-7 ft are prevalent in the remainder of the eastern Gulf,
east of 90W. Moderate or weaker winds and 2-4 ft seas prevail
elsewhere.

For the forecast, a broad ridge centered over the Ohio Valley extends
SE into the western Atlantic, behind a stalling cold front across
the central Caribbean. This pattern will support moderate to fresh
NE winds over the E Gulf tonight. The high pressure will shift
eastward into the eastern U.S. through Thu, causing fresh winds
to veer E, with strong winds developing in the Florida Straits
and adjacent waters through Fri. SE return flow is expected to
develop Sat through Sun.

...CARIBBEAN SEA...

A stationary front extends from Haiti to the Panama and Colombia
border near 8.5N77W. A few showers are noted near this boundary.
The pressure gradient between the strong ridge well north of the
islands and the frontal boundary result in fresh to strong
northerly winds in the waters west of the front. Seas in these
waters are 7-10 ft south of 18N and 4-7 ft elsewhere. Gentle to
light winds and moderate seas are prevalent in the rest of the
Caribbean Sea.

For the forecast, high pressure will build SE across the western
Atlantic through Fri. This will force the N portion of the front
to drift SE across Hispaniola tonight through Wed night before
gradually dissipating. Fresh to strong N winds behind the front
will become N to NE tonight 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, pulsing to strong each night.

...ATLANTIC OCEAN...

Please read the Special Features section for information about the
Significant Swell event in the north-central Atlantic.

A stationary front remains draped across the southwestern tropical
Atlantic, extending from 31N67W to the Turks and Caicos Islands
and then to Hispaniola. Scattered moderate to isolated strong
convection is evident north of 26N and between the frontal
boundary and 62W. The pressure gradient between the a strong ridge
over the eastern United States and the stationary front sustain
fresh to strong northerly winds, primarily west of the front. Seas
in these waters are 8-13 ft. The highest seas are found near
31N69W.

Divergence aloft is supporting isolated to scattered showers and
isolated thunderstorms from 15N to 26N and between 37W and 51W.
The remainder of the tropical Atlantic is dominated by broad
ridging. The weak low pressure system in the central Atlantic has
weakened into a surface trough that extends from 17N55W to 26N60W.
The pressure gradient between the 1053 mb high pressure near
47N31W and lower pressures associated with the aforementioned
trough sustain fresh to near gale-force easterly winds north of
25N and between 41W and 61W. This is supporting the very rough
seas discussed in the Special Features section. Farther east,
fresh to strong easterly winds and seas of 8-12 ft are present
east of 35W. Moderate or weaker winds and moderate seas prevail
elsewhere.

For the forecast W of 55W, strong high pressure will build into
the western Atlantic behind the SW tropical Atlantic front
through early Thu, causing the fresh to strong N winds to
continue, before gradually diminishing to moderate to fresh Thu
night and Fri. The front will move SE and reach from 31N61W to
central Hispaniola Wed evening, from 28N55W to the N Mona Passage
Thu evening, then gradually dissipate. Winds and seas will slowly
subside Fri night and Sat as high pressure weakens..

$$
Delgado
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