[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200602
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Fri Oct 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
0535 UTC.

...SPECIAL FEATURES...

Tropical Storm Tammy is near 13.8N 58.0W at 2 AM EDT, and is
moving west at 8 kt. Maximum sustained winds are 50 kt with gusts
to 60 kt, and the minimum central pressure is 1002 mb. Peak seas
are currently around 22 ft. Tammy is a sheared tropical cyclone
with numerous moderate to isolated strong convection observed from
07N to 16N and between 55W and 59W. A gradual turn to the
northwest with a decrease in forward speed is forecast later
today, and this motion should continue through Saturday. A more
northward motion is forecast to begin Saturday night or Sunday. On
the forecast track, the center of Tammy will move near or over
the Leeward Islands later today through Saturday, and then move
north of the Leeward Islands Saturday night and Sunday. Gradual
strengthening is expected to begin later today and continue into
this weekend. Tammy is forecast to be at or near hurricane
intensity when it moves near the Leeward Islands tonight and
Saturday. Heavy rains from Tammy will begin to affect the Leeward
and northern Windward Islands later this morning, spreading into
the British and U.S. Virgin Islands and Puerto Rico over the
weekend. 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. Please 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 reaches the Atlantic through the coast of
Guinea-Bissau near 12N16W and continues to 14N27W and then to
00N42W. Scattered moderate convection is observed from 03N to 15N
and east of 37W.

...GULF OF MEXICO...

A weak surface trough extends from 28N91W to 19N94W and satellite
imagery depict a few shallow showers near the boundary. The rest
of the basin is under a weak high pressure pattern and a dry
airmass that suppresses the development of showers and
thunderstorms. Moderate or weaker winds prevail across the Gulf,
while seas of 3-4 ft are found in the SE Gulf and 1-3 ft
elsewhere.

For the forecast, Tropical Storm Tammy is near 13.8N 57.1W at 11 PM
EDT, and is moving west-northwest at 9 kt. Maximum sustained winds
are 50 kt with gusts to 60 kt, and the minimum central pressure
is 1001 mb. Tammy will move to 14.3N 58.2W Fri morning, 15.3N
59.9W Fri evening, then strengthen to a hurricane near 16.6N
61.3W Sat morning. Hurricane Tammy will reach 18.0N 62.0W Sat
evening, 19.7N 62.5W Sun morning, and 21.5N 63.0W Sun evening.
Tammy will change little in intensity as it moves N of the Leeward
Islands late Mon. Elsewhere, a trough will persist over the
northwest Caribbean through Sat. Looking ahead, a weak front will
move into the northwest Caribbean by Mon then stall through Tue.

...CARIBBEAN SEA...

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

A surface trough extends from western Cuba to Belize and a few
showers are occurring within 120 nm to the east of the boundary. A
recent scatterometer satellite pass depict fresh to strong winds
in association with the strongest storms. 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 13N. No deep convection is present elsewhere in
the Caribbean.

Moderate to fresh easterly trade winds and seas of 3-6 ft are
found in the south-central Caribbean. Outside of the influence of
Tammy, moderate or weaker winds and 1-3 ft seas are prevalent in
the rest of the basin.

For the forecast, Tropical Storm Tammy is near 13.8N 57.1W at 11 PM
EDT, and is moving west-northwest at 9 kt. Maximum sustained winds
are 50 kt with gusts to 60 kt, and the minimum central pressure
is 1001 mb. Tammy will move to 14.3N 58.2W Fri morning, 15.3N
59.9W Fri evening, then strengthen to a hurricane near 16.6N
61.3W Sat morning. Hurricane Tammy will reach 18.0N 62.0W Sat
evening, 19.7N 62.5W Sun morning, and 21.5N 63.0W Sun evening.
Tammy will change little in intensity as it moves N of the Leeward
Islands late Mon. Elsewhere, a trough will persist over the
northwest Caribbean through Sat. Looking ahead, a weak front will
move into the northwest Caribbean by Mon then stall through Tue.

...ATLANTIC OCEAN...

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

A dissipating stationary front enters the tropical Atlantic near
31N57W and continues southwestward to 27N69W. Farther west, a
surface trough stretches from 23N75W to 31N79W. The interaction of
these boundaries with tropical moisture and divergence aloft
result in isolated to scattered showers, mainly north of 27N and
west of 60W.

The subtropical ridge centered near 33N37W 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 fresh to strong E-SE winds from 20N to 27N and
between 53W and 67W. Seas in these waters are 6-10 ft. A cold
front enters the basin near 31N12W and continues to 28N37W.
However, no deep convection is associated with this boundary.
Moderate to fresh northerly winds are evident behind the frontal
boundary, along with seas of 6-11 ft. In the remainder of the
basin, moderate or weaker winds and moderate seas prevail.

For the forecast W of 55W, Tropical Storm Tammy is near 13.8N 57.1W at 11 PM
EDT, and is moving west-northwest at 9 kt. Maximum sustained winds
are 50 kt with gusts to 60 kt, and the minimum central pressure
is 1001 mb. Tammy will move to 14.3N 58.2W Fri morning, 15.3N
59.9W Fri evening, then strengthen to a hurricane near 16.6N
61.3W Sat morning. Hurricane Tammy will reach 18.0N 62.0W Sat
evening, 19.7N 62.5W Sun morning, and 21.5N 63.0W Sun evening.
Tammy will change little in intensity as it moves to the N of the
Leeward Islands late Mon. Elsewhere, a stationary front from
31N58W to eastern Cuba will weaken today before dissipating. High
pressure will build over the area in the wake of the front. The
next frontal system will move offshore the southeastern United
States Fri night.

$$
DELGADO
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