[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 031655
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sun Oct 3 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
1655 UTC.

...SPECIAL FEATURES...

Hurricane Sam is centered near 37.7N 54.6W at 03/1500 UTC or 545
nm S of Cape Race Newfoundland, moving NE at 14 kt. Estimated
minimum central pressure is 964 mb. Maximum sustained wind speed
is 85 kt with gusts to 105 kt. Sam remains a well-organized
hurricane as it moves further into the mid-latitudes. Numerous
moderate and isolated strong convection extends outward from the
center 100 nm. Maximum significant wave height is estimated at 41
ft, with seas 12 ft and greater extending outward as far as 360
nm from the center. A general track to the NE at a faster forward
speed is expected over the next couple of days. The cyclone is
forecast to slow down over the north Atlantic around midweek.
Gradual weakening is forecast during the next few days, and Sam is
expected to transition into a powerful post-tropical cyclone on
Monday. Please read the latest High Seas Forecast issued by the
Ocean Prediction Center at website
https://ocean.weather.gov/mobile/mobile_product.php?id=NFDHSFAT1
and the latest NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Tropical Depression Victor is centered near 16.1N 40.3W at
03/1500 UTC or 940 nm W of the Cabo Verde Islands, moving NW at
10 kt. Estimated minimum central pressure is 1007 mb. Maximum
sustained wind speed is 30 kt with gusts to 40 kt. Strong wind
shear continues to displace the convection to the E semicircle.
Scattered moderate to strong convection extends outward from the
center 400 nm in the NE quadrant and 300 nm in the SE quadrant.
Maximum significant wave height near the center is estimated to be
near 14 ft and the seas are expected to gradually decrease over
the next few days. A general NW motion is expected to continue
over the next couple of days. Some gradual weakening is expected
during the next couple of days, and Victor is forecast to become a
remnant low by late Monday and dissipate on 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...

An Atlantic tropical wave has its axis along 20W, south of 20N,
and it is moving W at 15 kt. No deep convection is noted in
association with this wave.

A Caribbean tropical wave has its axis along 69W, south of 20N,
extending from E Hispaniola to W Venezuela, and it is W at 15 kt.
Scattered moderate to strong convection is noted with and ahead
of the wave N of 14N and between 65W and 75W.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Senegal near 15N17W
to 05N25W. The ITCZ is from 05N25W to 07N36W. The ITCZ then resumes
from 09N44W to the coast of Guyana near 06N57W. Scattered
moderate to isolated strong convection is observed within 100 nm
of either side of the monsoon trough and ITCZ between 19W and
37W.

GULF OF MEXICO...

A dome of high pressure positioned between the Outer Banks and
Bermuda extends SW to the Gulf of Mexico, allowing for a weak
pressure gradient across the basin. Moderate E winds are noted in
the SE Gulf, while weaker winds prevail elsewhere. Divergence
aloft and a surface trough in the W Gulf, extending from 29N91W to
20N96W, result in a broken line of scattered showers and isolated
thunderstorms extending from the NE Gulf to near the coast of
Veracruz. Another surface trough is located in the central Bay of
Campeche and a few showers are seen near the trough axis. The rest
of the Gulf enjoys fairly tranquil weather conditions. Seas are
3-5 ft in the Gulf, with the highest seas occurring in the E Gulf
waters.

For the forecast, weak ridge of high pressure north of the Gulf
along 34N will move eastward through Tue, supporting tranquil
conditions across all but the southeast sections of the basin. A
weak cold front will move across the Gulf on Mon and Tue, with little
enhancement of the winds and seas.

CARIBBEAN SEA...

A sharp upper-level trough extends from the NW Bahamas, across
central Cuba to the SW Caribbean Sea. Divergence aloft and deep
tropical moisture results in a large area of showers and
thunderstorms from the central Caribbean to well north of
Hispaniola, mainly between 67W and 77W. Scattered moderate
convection is also noted in the SW Caribbean from the coast of
Panama to 13N and between 76W and 81W. The NW Caribbean enjoys
fairly tranquil weather conditions.

A recent scatterometer satellite pass show fresh to locally
strong trades occurring in the E and central Caribbean Sea, with
some of the strongest winds likely associated with the
thunderstorms in the area. Moderate to locally fresh trades are
found elsewhere in the basin. Seas of 5-7 ft are present in the
central and E Caribbean Sea, while 3-5 ft seas are noted in the W
and SW Caribbean.

For the forecast, high pressure will build north of the area.
this will increase winds and seas across the central Caribbean Mon
and Tue. Moderate N to NE swell will affect the tropical Atlc
waters through Tue.

ATLANTIC OCEAN...

Refer to the Special Features section above for details on
Hurricane Sam and Tropical Depression 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.

The sharp upper level trough over the NW Bahamas, a surface trough
that extends from 26N66W to Hispaniola, and plenty of tropical
moisture result in a large area of showers and thunderstorms that
extends from the central Caribbean to 26N and between 66W and 74W.
A recent scatterometer satellite pass show fresh to locally strong
easterlies occurring from the north coasts of Cuba and Hispaniola
to 29N and between 66W to the NW Bahamas, with the strongest winds
occurring off the NE coast of Cuba and the central Bahamas in
association with strong convection. Another surface trough extends
from just south of Hurricane Sam, enters the tropical Atlantic
near 31N55W to 26N62W. Widespread showers are noted E of the
trough axis to 50W. Satellite-derived wind data indicate that
fresh to strong S-SW winds are occurring in association with these
showers.

A broad 1026 mb ridge located near the Azores dominates most of
the NE Atlantic. The pressure gradient between the ridge and lower
pressures in South America results in fresh to locally strong trades
S of 20N and between 50W and the Lesser Antilles as seen in recent
satellite-derived wind data and surface observations. The
strongest winds are occurring in the waters near the Windward
Islands. A similar pressure gradient situation occurs in the NE
Atlantic between the ridge and lower pressures found in NW Africa,
producing fresh to locally strong NE winds E of 22W and N of 22N,
with the strongest winds occurring in the waters surrounding the
Canary Islands. Moderate to locally fresh winds are present in the
rest of the basin. Outside of the influence of Hurricane Sam and
T.D. Victor, seas of 5-8 ft prevail in the tropical Atlantic.

For the forecast, swells generated from Hurricane Sam, centered
well NE of the area, will impact the area waters through Mon.
High pressure along the mid Atlc coast will drift slowly eastward
through mid week. This will produce moderate to fresh trade winds
south of 23N and east of the Bahamas through Tue before spreading
into the southeast Bahamas. Active weather is expected to develop
across the waters E of 75W and NE the Bahamas Mon night through
Tue as a surface trough develops and drifts NW.

$$
DELGADO
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