[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 082137
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sat Oct 9 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 1800 UTC surface analysis and satellite imagery through
2200 UTC.

...SPECIAL FEATURES...

A low pressure system located a couple of hundred miles east of
the coast of South Carolina is gradually becoming better defined.
Although the associated shower and thunderstorm activity is
currently disorganized, environmental conditions could briefly
become marginally conducive for the low to acquire subtropical
characteristics by Saturday night and early Sunday. By early next
week, the low is expected to interact with a frontal boundary,
which should end the opportunity for any subtropical or tropical
formation. The low is forecast to meander offshore the Carolinas
today, and then slowly move back toward the west-northwest and
northwest on Saturday, bringing the system closer to the coast of
North Carolina. Interests along the coast of North and South
Carolina should monitor the progress of this system. Regardless
of development, intermittent periods of locally heavy rains and
gusty winds will affect eastern portions of the Carolinas through
the weekend. The disturbance has a medium chance of development
over the next 48 hours. Please read the latest Tropical Weather
Outlook at https://www.hurricanes.gov and the High Seas Forecast
from the Ocean Prediction Center at https://ocean.weather.gov for
more information.

...TROPICAL WAVES...

The axis of a tropical wave is near 40W south of 16N, moving W
at 15 to 20 kt. Deep convection near the southern portion of this
wave is mainly associated with the nearby ITCZ. The northern
portion is devoid of deep convection due to dry Saharan air.

The axis of a tropical wave is near 68W south of 19N, moving W
at 15 to 20 kt. Scattered moderate convection is noted from 12N
to 16N and between 64W and 70W.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from 12N16W to 09N18W. The ITCZ
continues from 09N18W to 08N30W. It resumes from 07N41W to
04N51W. Scattered moderate convection is noted from 04N to 11N
between 18W and 32W, and from 02N to 09N between 41W and 49W.

...GULF OF MEXICO...

A cold front extends from northern Florida to the central Gulf. A
pre- frontal trough extends from central Florida to near 26N84W.
Scattered moderate and isolated strong convection is noted within
240 nm SE of the front. A surface trough extends from 22N90W to
the Bay of Campeche. Scattered moderate convection is within 90
nm of the trough axis. High pressure prevails elsewhere over the
NW Gulf. Gentle to moderate winds prevail over the northern Gulf
west of the cold front. Light to gentle winds are noted
elsewhere. Seas are in the 3-4 ft range over the SW Gulf, and 1-3
ft elsewhere.

For the forecast, the pressure gradient between high pressure
over the western half of the Gulf and the trough in the Bay of
Campeche supports moderate to fresh northerly winds over the
Veracruz adjacent waters. These winds are forecast to diminish
this evening. Weak high pressure will build across the basin this
weekend into early next week, and support moderate to locally
fresh return flow W of 90W Sun through Wed night.

...CARIBBEAN SEA...

A weak pressure gradient prevails over the Caribbean. Moderate
to fresh winds prevail over the south central Caribbean with
gentle to moderate winds over the eastern Caribbean as well as
the north central Caribbean. Light to gentle winds are over the
western Caribbean. Seas are in the 6-7 ft range over the south
central Caribbean, and 3-5 ft elsewhere.

For the forecast, moderate to locally fresh trades are expected
mainly across the eastern half of the Caribbean through Tue.

...ATLANTIC OCEAN...

Low pressure is centered north of the area. An associated surface
trough extends from the low SW to central Florida. Scattered
moderate and isolated strong convection is noted west of the
trough as well as within 90 nm east of the trough. Another
surface trough extends from 28N61W to 20N69W. Scattered moderate
convection is noted within 120 nm of the trough axis north of
22N. Another trough extends from 30N52W to 28N48W. Scattered
moderate convection is noted within 180 nm of the trough axis. A
third trough extends from 16N52W to 09N58W. Scattered moderate
and isolated strong convection is noted within 120 nm of the
trough axis. Moderate to fresh winds prevail over the deep
tropics south of 20N with seas in the 6-8 ft range. Light to
gentle winds generally prevail over the tropical and subtropical
waters north of 20N. Seas are in the 5-7 ft range east of 55W in
northerly swell, and in the 3-5 ft range over the open waters
west of 55W. West of the Bahamas, seas are in the 1-3 ft range.

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. An ash plume is partially identifiable on satellite imagery
drifting westward toward the Tenerife Island. Top is estimated
with Webcams at 11,000 ft. 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/.

For the forecast W of 65W, the low pressure system located a
couple of hundred nm east of the coast of South Carolina
continue to support scattered showers and tstms across the
offshore waters N of the Bahamas. By Saturday night and early
Sunday, environmental conditions could briefly become marginally
conducive for the low to acquire subtropical characteristics.
However, by early next week, the low is expected to interact with
a frontal boundary, which should hinder the opportunity for any
subtropical or tropical formation. The low is forecast to move
WNW on Saturday. Regardless of development, the low will continue
to support active weather over the northern offshore waters
tonight, with this activity extending across the Bahamas during
the remaining weekend.

$$
AL
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