[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 020546
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...SPECIAL FEATURES...

Hurricane Sam is centered near 32.1N 61.1W at 02/0600 UTC or 185
nm E of Bermuda moving NNE at 15 kt. Estimated minimum central
pressure is 945 mb. Maximum sustained wind speed is 120 kt with
gusts to 145 kt. Numerous moderate to scattered strong
convection extends outward from the center 240 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
40 ft, with 12 ft seas extending outward as much as 315 nm from
the center. Sam is expected to turn NE by tonight. Weakening is
anticipated over the next couple of days, but Sam should remain
a major hurricane into Sunday.  Early next week, Sam should
begin to transition to a strong extratropical storm. 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 Storm Victor is centered near 12.3N 35.3W at 02/0300
UTC or 700 nm WSW of the Cabo Verde Islands moving WNW at 11 kt.
Estimated minimum central pressure is 999 mb. Maximum sustained
wind speed is 50 kt with gusts to 60 kt. Scattered moderate to
strong convection is occurring in the NE quadrant between
120-420 nm from the center. There is no convection in the other
three quadrants. Maximum significant wave height near the center
is estimated to be near 20 ft, and the seas should gradually
diminish during the next couple days. Victor is forecast to
gradually turn NW over the next several days. The tropical storm
is forecast to weaken to a remnant low Monday night. 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 axis extends along 56W from 05N to 19N, moving W
at 15 kt. Scattered showers and isolated tstorms are within 120
nm either side of the wave axis from 08N-14N.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Guinea near 10N
14.5W to 06N20W. The ITCZ then extends from 06N20W to 07N28W.
The ITCZ resumes to the west of Tropical Storm Victor near
07N39W to 07N56W. Aside from convection associated with Victor
and the tropical wave described in the sections above, scattered
moderate to isolated strong convection extends from 02N-13N east
of 19W. Scattered moderate convection is noted within 60 nm
either side of a line extending from 01N24W to 04N28W to 11N31W.
Similar convection is seen near the ITCZ from 05N-09N between
42W-53W.

GULF OF MEXICO...

An eastward-moving short-wave digging over the Texas panhandle
is inducing upper-level diffluence and rising motion ahead of it
over the western Gulf of Mexico. This, coupled with high
moisture content noted in Total Precipitable Water imagery, is
leading to scattered moderate and isolated strong convection
over the west-central and NW Gulf of Mexico from 24N-29N between
94W-98W. The latest ASCAT data show mainly moderate E winds
across the basin, except for some fresh winds in the Florida
Straits, near the Yucatan Peninsula and in the convection near
the Mouth of the Rio Grande River. Seas are 2 to 4 ft across the
basin.

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

CARIBBEAN SEA...

A fairly modest pressure gradient is supporting mainly moderate
trades over the basin, with seas of 2 to 4 ft. The latest ASCAT
data show some locally fresh trades in the SE and south-central
Caribbean. An upper-level trough extending from eastern Cuba to
Costa Rica is supporting scattered showers and tstorms covering
much of the eastern and central Caribbean Sea, east of 74W.
Moisture in this area is also being aided by a tail of moisture
that extends southwestward all the way from Hurricane Sam. West
pf 74W, additional showers and storms are found near Jamaica, as
well as in the SW Caribbean south of 12N, associated with the
east Pacific monsoon trough.

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 starting later today and
continuing 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.

Aside from Hurricane Sam and Tropical Storm Victor, the tropical
N Atlantic is dominated by ridging from a high pressure of 1028
mb centered near 37N39W. A ridge axis extends SW from that high
pressure to the Virgin Islands. Moderate anticyclonic winds
prevail near the ridge axis. Southeast of the ridge axis, fresh
NE trades prevail. These winds become strong closer to Tropical
Storm Victor. Hurricane Sam is located NW of that ridge axis, a
couple hundred nm east of Bermuda. Mostly moderate to fresh NE
winds prevail across the western Atlantic, west of 67W and south
of 31N. Outside of the two tropical cyclones, seas of 6 to 9 ft
prevail across the basin. A line of broken showers and
thunderstorms about 60 nm wide extends from 27N56W to 20N63W.
Additional showers and tstorms are noted over the waters from
just north of Puerto Rico to just north of the Windward Passage.
Isolated showers and tstorms are seen in the vicinity of the NW
Bahamas.

Hurricane Sam is northeast of the forecast area near 32.1N 61.1W
and moving NNE near 15 kt. Swell from Hurricane Sam has reached
to the Bahamas, and will reach the east coast of Florida and
Georgia later today. In the area north of 26N and east of 68W,
swell from Sam will be quite significant through today. Swell
over the western Atlantic will begin to subside on Sunday as Sam
accelerates northeastward over the north Atlantic. High pressure
will build into the W Atlantic in the wake of Sam, which will
bring moderate to occasionally fresh winds through Tue.

$$
Hagen
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