[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121025
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Sun Dec 12 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 0600 UTC surface analysis and satellite imagery through
1000 UTC.

...SPECIAL FEATURES...

Gulf of Mexico Gale Warning: A strong cold front continues to move
across the northern Gulf waters, extending from the western
Florida Big Bend to 29N95W to 23N97W. A recent scatterometer
satellite pass depict gale force winds across the adjacent waters
of southern Tamaulipas and northern Veracruz. Seas are up to 12
ft in this area. Winds will diminish below gale force later this
morning after 12Z. Please refer to the latest High Seas Forecast
product issued by the National Hurricane Center at the website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough is exiting Africa through the coast of Guinea-
Bissau near 12N16W to 07N23W. The ITCZ extends from 07N23W to
02N50W. Scattered showers prevail in the vicinity od the monsoon
trough mainly E of 20W.

GULF OF MEXICO...

Refer to the section above for details on the Gale Warning in
effect for the western Gulf.

The weather conditions ahead of the aforementioned cold front are
tranquil. To the SW, a surface trough extends from 23N89W to
19N91W, but it is not producing any significant convection.
Strong to near gale force N-NE winds and seas of 4-8 ft are
present behind the front. Moderate or weaker, except for locally
fresh E-NE winds in the Florida Straits and offshore NW Yucatan,
are occurring ahead of the front. Seas are 2-4 ft in the rest of
the basin.

For the forecast, patchy marine fog will lower visibility in the
early morning hours along the NE Gulf. A high pressure ridge
extending from the Atlantic to the central Gulf will continue to
shift eastward in response to the strong cold front that is moving
across the northern Gulf. Gale force winds are expected to
continue over the far west Gulf through Sun 12Z. Seas of 12 ft are
expected in the wake of the front with the strongest winds. The
front will weaken as it reaches from central Florida to the SW
Gulf today and dissipate through Mon. Fresh to strong east winds
will spread westward through the Straits of Florida and to the
eastern Gulf S of 26N Mon through midweek along with building
seas.

CARIBBEAN SEA...

The tight pressure gradient as a result of the 1031 mb subtropical
ridge over the NW Atlantic and lower pressures over northern South
America result in fresh to strong trades in the central and NE
Caribbean Sea. The strongest winds are occurring offshore southern
Hispaniola and offshore NW Colombia, as indicated by a recent
scatterometer satellite pass. Seas of 5-8 ft are present in the
central, SW and eastern Caribbean Sea. A recent altimeter
satellite pass showed 8-9 ft seas offshore NW Colombia. Moderate
or weaker winds are found in the rest of the basin, except for
locally fresh trades off the lee of Cuba and the Gulf of Honduras.
Seas of 2-5 ft prevail in the NW Caribbean. The weather
conditions remain fairly tranquil due to a dry airmass dominating
the basin.

For the forecast, the pressure gradient between the ridge across the
northern Caribbean and the Colombian/Panamanian low will
continue to support fresh to strong easterly trades over the
south-central Caribbean through the weekend and early next week.
Moderate to fresh trades will prevail elsewhere. High pressure
will continue to strengthen over the western Atlantic through
the forecast period, resulting in pulsing fresh to locally
strong northeast winds and building seas in the Windward
Passage, the lee of Cuba and south of Hispaniola.

ATLANTIC OCEAN...

A broad high pressure regime dominates the tropical Atlantic
anchored by strong subtropical ridges over the north Atlantic. As
a result of the pressure gradient between the subtropical ridges
and lower pressures over NW Africa and the deep tropics, fresh to
strong easterly winds are found mainly S of 26N, with the
strongest winds occurring from 17N to 24N and between 31W and
63W. Strong trades are also noted in the entrance of the Windward
Passage. Seas of 7-10 ft are prevalent over a large area in the
tropical Atlantic, mainly E of 65W and S of 27N. Seas of 4-7 ft
are found elsewhere in the basin.

The Cumbre Vieja volcano, on the island of La Palma in the Canary
Islands, has been erupting since 19 September 2021. Marine and
aviation interests should monitor this ongoing situation by
reading the Volcanic Ash Advisory issued by Meteo-France, at
http://vaac.meteo.fr/volcanoes/la-palma/.

For the forecast west of 65W, high pressure is producing moderate
to fresh NE to E winds S of 22N, and mainly gentle to moderate
winds N of 22N. A cold front will move off the northeast Florida
coast today, and reach from near 31N70W to Central Florida by
tonight. This front is forecast to dissipate over the southeastern
waters on Mon night. High pressure behind the front will bring
fresh to strong northeast to east winds mainly across the waters
south of 27N by Mon night. These conditions are expected to last
through midweek.

$$
ERA
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