[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 051051
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Tue Oct 5 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 0600 UTC surface analysis and satellite imagery through
0930 UTC.

...SPECIAL FEATURES...

The center of newly classified Post-Tropical Cyclone Sam was
located near 51.0N 39.4W AT 05/0900Z, moving toward the N, or 10
degrees, at 20 knots. The estimated minimum central pressure is
970 mb. The maximum sustained wind speeds are 70 knots with gusts
to 85 knots. Maximum wave heights are estimated to be near 47
feet east of the center. Associated large NW to N swell had spread
well south of Sam, with seas to 12 ft extending to near the
discussion area near 31N46W. Satellite imagery indicates that Sam
has taken on extratropical characteristics as it has begun to
interact with a frontal boundary. Scattered moderate convection is
noted within 210 nm across the NW and 420 nm across the NE
quadrants, while only low clouds prevail across the south
semicircle. This is the last advisory that will be issued on Sam.
For additional information and forecasts, please, read the latest
High Seas Forecast issued by the Ocean Prediction Center, at the
website
https://ocean.weather.gov/mobile/mobile_product.php?id=NFDHSFAT1,
and the last NHC Advisory and Public Advisory, at
www.hurricanes.gov.

...TROPICAL WAVES...

An Atlantic Ocean tropical wave is along 39W, from 20N southward,
moving W 15 knots. Scattered moderate to strong convection is
noted from 05.5N to 10.5N between 35W and 46W. Dry Saharan air
follows this wave and extends from 37W to the African coast.

A Caribbean Sea tropical wave is along 76W,from 17N southward,
moving W 10 to 15 knots. An upper level trough extending from the
western Atlantic across the central Bahamas to the Gulf of
Honduras is supporting active convection with and ahead of this
wave. Scattered moderate to strong convection is noted from 13.5N
to 19N between 73W and 83W.

...MONSOON TROUGH/ITCZ...

The monsoon trough is mostly inland across Africa, with only a
small part extending off the coast along 12.5N to 18W. The ITCZ
extends from 06N21W to 07.5N35W. Widely scattered moderate to
isolated strong is from 02.5N to 14N between the W coast of Africa
and 31W. to 14W and 45W. Isolated moderate is elsewhere from 07.5N
to 11N between 49W and 60W.

GULF OF MEXICO...

A weakening cold front extends from a 1013 mb low pressure
center across southern Mississippi to the coast of Mexico near
20N97W. Scattered moderate isolated strong convection noted within
120 nm east of the front, from 27N northward into the Florida
Panhandle. Widely scattered moderate isolated strong convection is
within 90 nm east of the front southward of 27N, and along the
Mexican coast near Veracruz.

Mainly gentle northerly winds prevail west of the front and gentle
southeast to south winds east of the front. Seas are generally 3
ft or less.

A weak ridge north of the Gulf along 30N will move eastward
through Wed, supporting tranquil conditions across the basin. The
weak cold front over the NW Gulf will move slowly SE and stall
from the N central Gulf to central Bay of Campeche Wed then
dissipate Thu. Fresh to occasionally strong northerly winds will
develop within 60 nm of the coast of Veracruz tonight through Wed,
with seas there building to 4-5 ft.

CARIBBEAN SEA...

An upper level trough extends from the western Atlantic near
31N75W SSW across the central Bahamas and western Cuba to the
Gulf of Honduras. This is promoting unstable conditions and
supporting convection described above associated with the tropical
wave. Isolated moderate convection is seen south of 11N between
the coast of Colombia and southeast Nicaragua.

Fresh to strong trade winds prevail across most of the central
Caribbean and extend northeastward through the Anegada Passage.
Seas range from 7 feet to 10 feet, as the gradient tightens
between the Bermuda high and the east Pacific Ocean monsoon
trough. Moderate trade winds and seas of 3 to 6 ft prevail west
of the tropical wave.

High pressure just E of Bermuda will gradually slide eastward
through the middle of the week. This pattern will produce fresh to
strong trade winds across the NE and central Caribbean through
Tue night. Fresh to strong trade winds will then persist across
the central Caribbean through Thu. Moderate N to NE swell from Sam
will affect the tropical Atlc waters through Wed night. Winds and
seas will diminish significantly by Fri.

ATLANTIC OCEAN...

An upper level trough extends from the western Atlantic near
31N75W SSW across the central Bahamas and western Cuba to the
western Caribbean. This is promoting a surface trough to the east,
from 30N70W to 24N76W. Scattered moderate to strong convection
continues within 240 nm east of the trough, while isolated
moderate convection is seen offshore of north Florida and SE
Georgia. Moderate to locally fresh SE winds prevail between the
surface trough and 70W, where seas are 5 to 7 ft in NE swell.
Active weather will continue along and east of the trough
through Wed as it shifts gradually NW. Upper level winds are
expected to be unfavorable for and significant develop of this
system.

A surface trough, the remnants of Victor, extends from 25N47W to
17N52W and is moving westward at 10-15 kt. Scattered moderate to
isolated strong convection is within 90 nm either side of the
trough north of 20N. Moderate to fresh winds at 20 kt or less are
found on either side of the trough. The trough will shift westward
and gradually dissipate through Wed.

The Cumbre Vieja volcano, that is on the island of La Palma in
the Canary Islands, has been erupting since 19 September at 1410
UTC. Marine and aviation interests should monitor this on-going
situation, by reading the Volcanic Ash Advisory, that is issued
by Meteo-France, at http://vaac.meteo.fr/volcanoes/la-palma/.

Moderate to fresh trade winds cover the remaining area south of
24N, while light to gentle winds are from 24N northward. Locally
strong NE winds are occurring near the coast of NW Africa in an
area of a tight pressure gradient. Fresh to locally strong winds
are near the Leeward Islands. Wave heights range from 7 to 11 feet
in NW to N swell from Sam across the waters east of 70W, with
highest seas near 31N45W.

High pressure just E of Bermuda will slide slowly eastward
through mid week. This will produce moderate to fresh trade winds
south of 25N and east of 74W through Tue before spreading into the
southeast Bahamas Wed. The swell generated from Hurricane Sam
will continue to impact the SW N Atlantic including the Bahamas
through Wed night. Active weather is expected to continue through
Wed across the waters within 300 nm E of a surface trough from the
SE Bahamas to 30N70W, as the trough shifts NW.

$$
Stripling
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