[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202330
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sat Oct 21 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 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...SPECIAL FEATURES...

Hurricane Tammy is centered near 14.3N 59.2W at 20/2100 UTC or
110 nm ESE of Martinique, moving WNW at 6 kt. Estimated minimum
central pressure is 991 mb. Maximum sustained wind speed is 65
kt with gusts to 80 kt. Peak seas are currently near 24 ft.
Numerous moderate to strong convection is noted from 11N to 16N
between 56W and 62W. A turn toward the northwest is anticipated by
tonight, followed by a NNW and N turn Saturday night through
Sunday night. On the forecast track, the center of Tammy will move
near or over portions of the Leeward Islands tonight through
Saturday night, and then move north of the northern Leeward
Islands on Sunday. Gradual strengthening is forecast during the
next couple of days, and Tammy is expected to be a hurricane while
it moves near or over portions of the Leeward Islands. Heavy
rains from Tammy will begin to affect the Leeward and northern
Windward Islands later today and into Saturday morning, spreading
into the British and U.S. Virgin Islands and Puerto Rico as early
as Sunday. This rainfall may produce isolated flash and urban
flooding, along with isolated mudslides in areas of higher
terrain. Swells generated by Tammy will continue to affect
portions of the Lesser Antilles during the next few days. These
swells are likely to cause life-threatening surf and rip current
conditions. Please consult products from your local weather office
and read the latest HIGH SEAS FORECAST issued by the National
Hurricane Center at website -
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Tammy
NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov
for more details.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coastal plains of Guinea-
Bissau near 11N16W to 06N26W to 10N37W. The ITCZ extends from
10N37W to 08N46W. Scattered moderate to isolated strong convection
is noted from 05N to 10N between 41W and 49W. +Scattered moderate
convection is noted from 04N to 14N between 15W and 41W.

...GULF OF MEXICO...

A weak surface trough extends from 25N89W to 19N93W and has
isolated showers near it. The rest of the basin is under a weak
high pressure pattern and a dry airmass that is suppressing
development of showers and thunderstorms. Moderate to locally
fresh winds are likely occurring along the Florida Panhandle.
otherwise, moderate or weaker winds prevail across the Gulf, with
seas of 2-4 ft in the eastern Gulf and 1-3 ft elsewhere.

For the forecast, high pressure will shift SW through Sat,
allowing a cold front to move into the NE Gulf tonight, then
slowly dissipate as it moves across the eastern Gulf through Sat.
Another cold front will follow, moving across the eastern Gulf Sun
night through Mon, before stalling southeast of the region by Mon
night into early Tue. Looking ahead, high pressure building in
the wake of the front will support moderate to fresh E winds and
building seas Sun night through mid week.

...CARIBBEAN SEA...

Please see the Special Features section above for more details on
Hurricane Tammy located just east of the Lesser Antilles.

A surface trough extends from western Cuba to Belize and is
producing scattered moderate convection within 70 nm of its axis.
Meanwhile, the eastern Pacific monsoon trough enters the SW
Caribbean Sea near 11N83W and continues eastward to northern
Colombia near 11N75W. Scattered moderate to isolated strong
convection is evident on satellite imagery south of 14N. Strong
thunderstorms are also noted along the coast of Venezuela.
Otherwise, no deep convection is present elsewhere in the
Caribbean.

Moderate easterly trade winds are noted in the eastern Caribbean.
Seas are 3 to 5 ft due to the influence of Tammy. Moderate to
locally fresh N winds are noted in the NW Caribbean behind the
trough with seas to 4 ft. Otherwise, light to gentle winds with
seas 2 to 4 ft seas are prevalent in the rest of the basin.

For the forecast, Hurricane Tammy is near 14.3N 59.2W at 5 PM
EDT, and is moving west-northwest at 6 kt. Maximum sustained winds
are 65 kt with gusts to 80 kt, and the minimum central pressure
is 991 mb. Tammy will move through the northern Leeward islands
through Sun, reaching 15.3N 60.1W Sat morning, 16.7N 61.2W Sat
afternoon, 18.1N 62.1W Sun morning, and 19.5N 63.0W Sun afternoon.
Tammy will continue to move north of the area Sun night through
the early part of the week. Elsewhere, a trough will persist over
the northwest Caribbean into Sat. Looking ahead, a weak cold front
will move into the northwest Caribbean by late Mon, then stall
and weaken from eastern Cuba to northern Belize Tue.

...ATLANTIC OCEAN...

Please see the Special Features section above for more details on
Hurricane Tammy located just east of the Lesser Antilles.

A surface trough enters the tropical Atlantic near 31N70W and
continues southwestward to 23N81W. To the east, another surface
trough extends from 30N63W to 28N72W. These two features combined
with divergent flow aloft is resulting in a broad area of
scattered moderate convection N of 21N and W of 65W. Another area
of scattered moderate convection is depicted north of Puerto Rico
and it is associated with a deep layer trough.

The subtropical ridge centered near 32N50W is the main feature of
interest in the central and eastern Atlantic outside of the deep
tropics. The pressure gradient between this high pressure and
Tammy sustain moderate to fresh E-SE winds from 20N to 31N and
between 53W and 67W. Seas in these waters are 6-10 ft. A cold
front extends from Mauritania to 28N38W and is producing no
convection. N of the boundary, moderate N winds and seas of 6 to
9 ft area present. Across the remainder of the basin, winds are
mainly moderate with seas of 4 to 7 ft.

For the forecast W of 55W, Hurricane Tammy is near 14.3N 59.2W at
5 PM EDT, and is moving west-northwest at 6 kt. Maximum sustained
winds are 65 kt with gusts to 80 kt, and the minimum central
pressure is 991 mb. Tammy will move across the northern Leeward
Islands through Sun, then continue on to 19.5N 63.0W Sun
afternoon, 20.8N 63.4W Mon morning, and 22.0N 63.4W Mon afternoon.
Tammy will change little in intensity as it moves to 24.5N 61.7W
Tue afternoon. Farther west, a weak cold front will move off the
northeast Florida coast overnight, then weaken as it moves
eastward over the waters north of 27N, before stalling and
dissipating east of Bermuda early in the week. A second front will
follow, moving off the northeast Florida coast late Sun, reach
from Bermuda to West Palm Beach, Florida by early Mon, then stall
along 21N Tue.

$$
AReinhart
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