[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212241
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Wed Dec 22 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 1800 UTC surface analysis and satellite imagery through
2230 UTC.

...SPECIAL FEATURES...

.ATLANTIC GALE WARNING...

A complex low is developing off the east coast of Florida,
consisting of 1006 mb low near 30N78W and a deep, 1001 mb low
over central Florida near 28N81W. The 1001 mb low will move into
the Atlantic off northeast Florida this evening. This will cause
SW to W winds to increase over the waters between northeast
Florida, Bermuda, and the northern Bahamas through early Wed with
seas reaching 8 to 13 ft. 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...

The ITCZ reaches from 02N20N to 00N30W to 00N50W. Scattered
moderate convection is evident from 01N to 04N between 45W and
50W.

...GULF OF MEXICO...

A cold front extends southwestward from a strong 1001 mb low
pressure near Kissimmee, Florida to the western tip of Cuba. A
surface trough reaches from the low pressure westward across the
east-central Gulf to 27N86W. Earlier scatterometer and altimeter
satellite data showed strong to near- gale force over the
eastern Gulf with 8 to 11 ft seas. But winds and seas are
rapidly diminishing over the eastern Gulf as the low pressure
lifts to the northeast. Moderate to fresh NW flow is noted
elsewhere with 5 to 7 ft seas in most areas, except for 3 to 5 ft
seas in the far northwest Gulf and over the coastal waters
across the northern Gulf. Dry and cool air is following the
front, and no significant shower or thunderstorm activity is
evident across the Gulf.

For the forecast, fresh to strong winds and seas of 7 to
9 ft over the eastern Gulf 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 S return flow will develop in the western
Gulf.

...CARIBBEAN SEA...

A cold front extends southwestward from the western tip of Cuba
to central Belize. Scattered showers and isolated thunderstorms
are active over the northwest Caribbean within 60 to 150 nm west
of the front. Fresh NW winds follow the front across the Yucatan
Channel, with seas near 8 ft. Light breezes and 2 to 4 ft seas
are evident ahead of the front over the northwest Caribbean. Generally
moderate trade winds with 4 to 6 ft seas are noted across the
remainder of the Caribbean.

For the forecast, the front will gradually stall from the
Windward Passage to offshore Nicaragua for the latter part the
week. Fresh N winds are expected behind the front, diminishing to
mainly moderate on Wed. Scattered showers and isolated
thunderstorms accompany the front. Elsewhere, moderate to fresh
trades will prevail over the central and eastern 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 seas of 8 to 9 ft will prevail through
Wed.

...ATLANTIC OCEAN...

Please see Special Features section above for information on gales
that will develop off the east coast of Florida this evening
through Wed morning.

A cold front reaches from 30N40W to 29N50W where it becomes
stationary to 29N65W, then transitions to a warm front to the
1006 mb low near 30N78W. Another frontal boundary reaches from
this same low pressure center to the 1001 mb low pressure over
central Florida. The subtropical ridge is displaced slightly
southward by the front, reaching along roughly 25N east of 70W,
and anchored by 1019 mb high pressure near 25N51W. Scattered to
numerous showers and thunderstorms are noted with 60 nm northeast
of the 1006 mb low. A few showers and thunderstorms are also
active from central Cuba to the northern Bahamas. Fresh to strong
SW winds are observed within 90 nm west of the frontal boundary
off northeast Florida. Moderate to fresh winds are evident
elsewhere west of 55W, except for light winds along the ridge
axis. Buoy data confirms seas are 8 to 10 ft north of the
Bahamas and west of 73W. Recent altimeter data shows 8 to 10 ft
seas north of 28N along the frontal boundary, associated with NW
swell. Elsewhere, moderate to fresh trade winds and 7 to 10 ft
seas are noted over the tropical Atlantic south of 20N with
northerly swell, and gentle to moderate winds and 7 to 9 ft seas
in northerly swell north of 20N.

For the forecast west of 65W, in addition to the gale warning, a
trailing cold front will cross the region tonight through Wed
night, bringing scattered showers and thunderstorms with it.
Building high pressure behind the low should lead toward tranquil
conditions Thu night through Fri night. Looking ahead, a strong
pressure gradient is likely to develop north of 29N this weekend
in between low pressure systems tracking along 40N and the
subtropical high, which will be situated along 25N, leading to
strong W winds and building seas north of 29N.

$$
Christensen
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