[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192127
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 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 1800 UTC surface analysis and satellite imagery through
1830 UTC.

...SPECIAL FEATURES...

Tropical Storm Tammy is centered near 13.7N 56.6W at 19/2100 UTC
or 170 nm E of Barbados, moving WNW at 11 kt. Estimated minimum
central pressure is 1001 mb. Maximum sustained wind speed is 50
kt with gusts to 60 kt. Peak seas are currently around 22 ft.
Numerous moderate to isolated strong convection is noted from
06N to 16N between 50W and 60W. A turn toward the northwest is
forecast on Friday, and this motion should continue through
Saturday. A 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 Friday and Saturday, and then
move north of the Leeward Islands Saturday night and Sunday.
Little change in strength is expected tonight, but gradual
strengthening is expected to begin on Friday and continue into
this weekend. Tammy is forecast to be at or near hurricane
intensity when it moves near the Leeward Islands Friday night
and Saturday. Heavy rains from Tammy will begin to affect the
Leeward and northern Windward Islands on Friday, 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 enters the tropical Atlantic near the border of
Senegal and Guinea-Bissau at 12.5N16.5W to 07N30W to 02N39W. The
ITCZ extends from 02N39W to NE of the coast of Brazil at 01N48W.
Numerous moderate to isolated strong convection is observed from
03N to 16N between 22W and 35W.

...GULF OF MEXICO...

The Gulf of Mexico remains under the influence of a surface ridge
along 26N/27N, which is providing with light to gentle
anticyclonic winds across the basin along with 1-3 ft seas,
except gentle to moderate NE-E winds from the Straits of Florida
to offshore the northern Yucatan Peninsula where seas are 3-5 ft.

For the forecast, high pressure extending from the Carolinas to
the Texas coast will shift into the southwest through Sat ahead of
a cold front moving into the northeast Gulf Fri night. The front
will weaken as it moves slowly across the eastern Gulf through Sun
and southeast of the Gulf Mon. Looking ahead, high pressure
building in the wake of the front will support moderate to fresh
NE to E winds Sun night through Tue.

...CARIBBEAN SEA...

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

Tropical Storm Tammy is centered near 13.7N 56.6W at 19/2100 UTC
or 170 nm E of Barbados, moving WNW at 11 kt. Estimated minimum
central pressure is 1001 mb. Maximum sustained wind speed is 50
kt with gusts to 60 kt.

A stationary front from eastern Cuba to the Gulf of Honduras has
dissipated to a remnant surface trough during the past several
hours. Scattered showers and thunderstorms are found from 13N to
22N between 80W and 80.5W. Similar convection is in the SW
Caribbean due to the extension of the eastern Pacific Ocean
monsoon trough along 09N/10N. Moderate to fresh trades along with
5-7 ft seas, locally to 8 ft near 12N77W, are in the S-central
Caribbean. Gentle to moderate winds on either side of the surface
trough along with 3-5 ft seas are across the remainder of the
basin.

For the forecast, Tammy will move to 14.2N 58.2W Fri morning,
15.0N 59.9W Fri afternoon, and 16.4N 61.4W Sat morning. Tammy
will strengthen to a hurricane near 17.9N 62.4W Sat afternoon,
move to 19.5N 63.1W Sun morning, then continue north of the area
through early next week. 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 east of the Lesser Antilles.

Tropical Storm Tammy is centered near 13.7N 56.6W at 19/2100 UTC
or 170 nm E of Barbados, moving WNW at 11 kt. Estimated minimum
central pressure is 1001 mb. Maximum sustained wind speed is 50
kt with gusts to 60 kt.

A dissipating stationary front extends from SE of Bermuda near
31N60W to across the SE Bahamas to eastern Cuba supporting widely
scattered showers and isolated thunderstorms within 240 nm either
side of the boundary. A surface trough is analyzed from 31N78W to
27N76W. Fresh to locally strong winds were measured by an earlier
ASCAT scatterometer pass from 27N to 31N E of the trough to 70W,
along with 5-7 ft seas. Similar winds are from 20N to 27N between
57W and 65W due to a locally tight pressure gradient. Ahead of
the front and to the NE of Puerto Rico, upper level diffluence
supports a broad area of numerous moderate to scattered strong
convection from 16N to 27N between 57W and 67W.

The remainder subtropical Atlc is under the influence of a ridge
supporting mainly moderate to fresh winds and moderate seas,
except gentle to moderate winds N of 29N between 35W and 55W
closes to the ridge axis. Some higher seas of 7-10 ft in NW swell
are noted behind a cold front which reaches from 31N20W to 29N30W
to 30N37W.

For the forecast W of 55W, Tammy will intensify to hurricane
strength as if moves by the northern Leeward Islands through Sat.
Hurricane Tammy will reach 19.5N 63.1W Sun morning, and 21.0N
63.3W Sun afternoon then change little in intensity as it moves
northward across the waters east of 65W through Tue. 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. Fresh to strong winds and
rough seas are forecast north of 27N Fri night through Sat night
with this system.

$$
Lewitsky
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