[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021708
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sat Oct 2 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 1200 UTC surface analysis and satellite imagery through
1705 UTC.

...SPECIAL FEATURES...

Hurricane Sam is centered near 33.9N 59.3W at 1500 UTC, or 290 nm
ENE of Bermuda, moving NE at 15 kt. Estimated minimum central
pressure is 945 mb. Maximum sustained wind speed is 115 kt with
gusts to 140 kt. Sam remains a well-organized hurricane as it
moves away from Bermuda. Numerous moderate to scattered strong
convection extends outward from the center 180 nm in the N
semicircle and 90 nm in the S semicircle. Scattered moderate
convection exists elsewhere within 300 nm in the NE quadrant.
Maximum significant wave height near the center is estimated at 45
ft, with seas 12 and greater extending outward as far as 300 nm
from the center. A general track to the NE with an increase in
forward speed is expected for the next few days. On the forecast
track, Sam will continue to move away from Bermuda. Some slow
weakening is forecast during the next 36 hours, followed by more
significant weakening early next week. Sam could become a powerful
post-tropical cyclone on Tuesday. Please read the latest High
Seas Forecast issued by the National Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT1.shtml and the latest NHC
Forecast/Advisory and Public Advisory at www.hurricanes.gov for
more details.

Tropical Storm Victor is centered near 13.1N 37.2W at 1500 UTC,
or 785 nm W of the Cabo Verde Islands, moving NW at 10 kt.
Estimated minimum central pressure is 1005 mb. Maximum sustained
wind speed is 35 kt with gusts to 45 kt. Scattered moderate to
strong convection is occurring in the NE quadrant between 120-360
nm from the center. There is no significant convection elsewhere
near the center. Maximum significant wave height near the center
is estimated to be near 16 ft, and the seas should gradually
diminish during the next couple days. A general NW motion is
expected to continue over the next few days. Strong wind shear
will continue to impact the tropical storm and Victor could become
a remnant low tonight. The system is then forecast to dissipate
by Tuesday. 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 NHC
Forecast/Advisory and Public Advisory at www.hurricanes.gov for
more details.

...TROPICAL WAVES...

A tropical wave has its axis along 62W, south of 19N, extending
across the Lesser Antilles and into E Venezuela, and it is moving
W at 15 kt. The wave is embedded in a dry airmass that is
suppressing the shower and thunderstorm activity.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Senegal near 14N17W
to 06N20W. The ITCZ then extends from 06N20W to 08N29W. The ITCZ
resumes near 07N41W to 06N54W. Aside from convection associated
with T.S. Victor, scattered moderate to isolated strong convection
is observed within 150 nm of the monsoon trough, mainly E of 21W.
Scattered moderate convection is also noted within 150 nm north
of the ITCZ between 42W and 60W.

GULF OF MEXICO...

The Gulf of Mexico is the SW periphery of a 1026 mb high pressure
position over the E United States. A surface trough is located in
the NW Gulf within 60 nm of the coast of Texas and NE Mexico,
especially from 30N94W to 24N97W. Scattered moderate convection is
present within 150 nm to the east of the trough axis. A weak
surface trough in the central Bay of Campeche is only producing a
few shallow showers. The rest of the basin enjoys fairly tranquil
weather conditions. Fresh E-SE winds are occurring in the E Gulf,
including the Florida Straits, while gentle to moderate
anticyclonic winds prevail elsewhere. Seas of 4-6 ft are prevalent
in the SE Gulf, with the highest seas occurring in the Florida
Straits. Seas of 2-4 ft are present elsewhere in the Gulf.

For the forecast, a weak ridge of high pressure will persist
north of the Gulf through tonight, supporting tranquil conditions
across the western half of the basin. Stronger higher pressure
will build across the region on Sun, allowing winds and seas to
increase over the SE Gulf. A weak cold front will move across the
Gulf on Mon and Tue, with little enhancement of the winds and
seas.

CARIBBEAN SEA...

An upper level trough over the W Atlantic reaches into the W
Caribbean Sea, enhancing the development of scattered showers and
isolated thunderstorms across the central and E parts of the
basin. Most of the convection is located E of 75W and N of 13N.
Scattered moderate convection is also observed in the SW
Caribbean, mainly within 170 nm north of Panama. Only a few
showers are present in the W Caribbean. A recent scatterometer
satellite pass show fresh to locally strong trades occurring in
the central and E Caribbean Sea, especially E of 75W. Fresh trades
are also present in the NW Caribbean, mainly N of 20N. Gentle to
moderate trades prevail elsewhere in the basin. Seas of 4-6 ft are
found E of 75W and 2-4 ft elsewhere.

For the forecast, high pressure will build north of the area this
weekend. This will bring an increase in trade winds and seas
across the central and E Caribbean as well as the tropical N
Atlantic this weekend through the middle of next week.

ATLANTIC OCEAN...

Refer to the Special Features section above for details on Major
Hurricane Sam and Tropical Storm Victor.

The Cumbre Vieja volcano on the island of La Palma in the Canary
Islands near 28.6N 17.8W has been erupting since September 19th.
High concentration of volcanic ash is found near the volcano.
Marine and aviation interests should monitor this ongoing
situation by reading the latest Volcanic Ash Advisory issued by
Meteo-France at http://vaac.meteo.fr/volcanoes/la-palma/ for
details.

An expansive 1027 mb high pressure positioned SW of the Azores
dominates most of the Atlantic. Aside from the influence of
Hurricane Sam, which continues to move away from the Tropical
Atlantic, and Tropical Storm Victor, the only other feature of
interest is an upper level trough over the W Atlantic. Divergence
aloft and plenty of tropical moisture results in scattered
showers and isolated thunderstorms N of Hispaniola to 24N and
between 65W to 71W, with a few showers occurring near the NW and
central Bahamas. The rest of the Atlantic enjoys fairly tranquil
weather due to very dry environmental conditions.

Satellite-derived wind data depict fresh NE breezes occurring W
of 70W and S of 28N, affecting the waters surrounding the NW and
central Bahamas and SE Florida. A large area of fresh to locally
strong NE breezes is found between Tropical Storm Victor and the
Lesser Antilles, mainly S of 20N, likely as the result of the
strong ridge near the Azores and lower pressures in South America.
The scatterometer satellite data also indicate fresh to locally
strong NE winds occurring N of 25N and E of 20W. Moderate to
locally fresh anticyclonic winds are present in the rest of the
basin. Outside of the two tropical cyclones, seas of 6 to 9 ft
prevail across the basin.

For the forecast, swells generated from Hurricane Sam, centered
NE of the area, will impact the area west of 62W through the
weekend. High pressure will build across the area in the wake of
Sam, which will bring moderate to fresh winds Mon through mid
week.

$$
DELGADO
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