[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 092200
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sun Oct 10 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...

Satellite-derived wind data and surface observations indicate that
a large, non-tropical low pressure system located about 150 miles
southeast of Morehead City and Wilmington, North Carolina, is
producing a broad area of gale-force winds to the west and north of
the center. Associated shower and thunderstorm activity has been
gradually increasing and becoming better organized today, and the
low could acquire subtropical characteristics late this afternoon
through early Sunday. However, by late Sunday and Monday,
environmental conditions should become unfavorable for any
further development. The low is forecast to move slowly
northwestward during the next day or so, and approach the North
Carolina coast tonight and early Sunday. Therefore, interests
along the North Carolina coast should monitor the progress of
this system.

Regardless of development, intermittent periods of locally heavy
rains and gusty winds will affect southeastern and eastern portions
of North Carolina during the next day or two. There is a medium
chance of development for this low over the next 48 hours. For
more details, please read the latest Tropical Weather Outlook at
https://www.hurricanes.gov and Mariners can read the latest 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 45W, south of 18N, moving W
at 15 to 20 kt. Scattered moderate to isolated strong convection
is observed from 05N to 10N and between 44W and 50W.

The axis of a tropical wave is near 59W, south of 20N, moving W
near 15 kt. Scattered moderate isolated strong convection is
noted from 12N to 19N between 55W and 61W.

The axis of a tropical wave is near 73W, south of 20N, moving W
at 15 to 20 kt. There is no deep convection associated with this
wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean through the coast of
Mauritania near 17N16W and continues SW to near 08N22W. The ITCZ
continues from 08N22W to 09N44W. Aside from convection noted in
the tropical waves section above, scattered moderate to isolated
strong convection is noted from 07N to 10N between 20W and 30W,
and from 04N to 12N between 35W and 44W.

...GULF OF MEXICO...

A surface trough extends off the coast of southern Florida to
near 25N85W. A second surface trough is found over the far SW
Gulf. Otherwise, high pressure prevails across the Gulf waters.
Light to gentle winds, and seas of 1-3 ft, prevail across the
Gulf waters.

For the forecast, a weak pressure gradient support light to
gentle variable winds with seas to 3 ft. A weak surface ridge
will start to build across the basin this evening and moderate to
locally fresh return flow will develop over the western half of
the basin, continuing through Thu night.

...CARIBBEAN SEA...

A weak pressure gradient prevails across the area. Moderate to
fresh winds are over the eastern and central Caribbean. Light to
gentle winds prevail over the western Caribbean. Seas are in the
3-5 ft range over the eastern and central Caribbean, and 1-3 ft
over the western Caribbean.

For the forecast, a tropical wave with axis will provide fresh
winds and scattered showers to the Lesser Antilles through
Monday. Shower activity associated with this wave will affect the
US/UK Virgin Islands and Puerto Rico Sun evening through Tue and
Hispaniola from Mon through Wed night. Seas to 8 ft will impact
the Atlantic waters E of the Lesser Antilles through Sun evening.
Otherwise, moderate to fresh winds in the eastern half of the
Caribbean will diminish to gentle to moderate early on Tue and to
light to gentle on Thu.

...ATLANTIC OCEAN...

A surface trough extends from 31N78W to central Florida.
Scattered moderate and isolated strong convection is noted within
120 nm east of the trough axis. A second trough extends from
31N41W to 28N47W. Scattered moderate convection is noted within
60 nm east of the trough. A third trough is noted from 27N53W to
25N69W. Scattered moderate convection is noted within 60 nm of
the trough axis. Moderate to fresh trade-winds prevail over the
tropical waters south of 20N. Light to gentle winds are noted
over the tropical and subtropical waters north of 20N. Seas are
in the 5-8 ft range south of 20N, and 3-6 ft over the open waters
north of 20N. Seas of 1-3 ft prevail west of the Bahamas.

The Cumbre Vieja volcano, that is on the island of La Palma in
the Canary Islands, has been erupting since 19 September 2021.
Currently, volcanic ash is not easily detectable due to cloud
cover. 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, A surface trough across the NW waters
will continue to produce showers and tstms across the Bahamas
and offshore zones W of 70W through Mon.

$$
AL
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