[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071709
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Oct 7 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
1705 UTC.

...TROPICAL WAVES...

An Atlantic tropical wave has its axis along 31W, south of 16N
and it is moving W around 15 knots. The convection near the
southern portion of the wave is described in the Monsoon
Trough/ITCZ section. The northern portion of the wave is
surrounded by dry Saharan air resulting in no deep convection
N of 08N.

Another Atlantic tropical wave has its axis along 56W, south of
19N and it is moving W around 15 knots. Divergence aloft is
interacting with the wave and another surface trough nearby
causing a large area of scattered showers and isolated
thunderstorms, mainly from 09N to 15N and between 53W and 62W.

A Caribbean tropical wave has its axis along 88W, south of 21N,
extending from the N Yucatan through W Central America and into
the E Pacific. The wave is moving W at 10-15 knots. Scattered
moderate convection is noted near the trough axis in the Gulf of
Honduras, mainly within 60 nm of Belize. Most of the wave is over
the E Pacific.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic Ocean through the southern
coast of Senegal near 13N17W to 08N19W. The ITCZ then continues
from 08N19W to 06N25W and to 06N31W. Another segment of the ITCZ
is found from 05N32W to 04N40W and to the coast of NE Brazil near
01S48W. Numerous moderate to isolated strong convection is
observed within 240 nm of the ITCZ between 16W and 40W.

GULF OF MEXICO...

The main feature of interest in the Gulf of Mexico remains a weak
stationary front that enters the basin near the Florida-Alabama
border and meanders S-SW to the central Bay of Campeche. A few
showers and isolated thunderstorms are seen on satellite imagery
near the frontal boundary, especially in the central Bay of
Campeche. Scattered moderate convection is also noted in the E Bay
of Campeche and within 90 nm of the N Yucatan coast and the Big
Bend area of Florida. The rest of the basin enjoys of fairly
tranquil weather conditions, especially the NW and W Gulf thanks
to continental dry air behind the stationary front.

A weak pressure gradient allows for a benign wind pattern across
the Gulf, with gentle to moderate cyclonic winds prevailing. The
exception is the W Bay of Campeche where moderate to locally fresh
N-NW winds are found, mainly within 60 nm of the coast of
Veracruz. Seas of 2-4 ft are found in the Bay of Campeche and SE
Gulf, especially in the Florida Straits, while 1-2 ft are
prevalent elsewhere.

For the forecast, the previously mentioned stationary front will
meander today before drifting NW and gradually dissipating through
Fri. High pressure over central and southern Mexico will support
moderate to locally fresh northerly winds over Veracruz adjacent
waters through Fri early in the evening. Weak high pressure will
build across the E half of the basin late this weekend into early
next week, and support moderate to locally fresh return flow W of
90W Sun through Mon.

CARIBBEAN SEA...

An upper level trough extends across Hispaniola and Puerto Rico to
the ABC islands, enhancing scattered moderate to isolated strong
convection over the E Caribbean, with the strongest convection
occurring near the Windward Islands. Scattered moderate to
isolated strong convection is also observed in the SW Caribbean
due to abundant moisture and enhancement from the eastern
extension of the E Pacific monsoon trough that enters the basin
through the coast of Costa Rica to a 1009 mb low near 10N77W to NW
Colombia. The convection extends from the coast of Nicaragua to NW
Colombia, mainly within 155 nm of the coasts of the countries in
the region. A drier environment is prevalent elsewhere in the
Caribbean Sea, resulting in fairly tranquil weather conditions.

A modest pressure gradient between a 1023 mb Bermuda High and
lower pressures in South America and the monsoon trough in the SW
Caribbean Sea results in a large area of fresh to strong trades
in the central and SW Caribbean, especially from 71W to 84W and
between 18N near the coasts of Hispaniola and Jamaica to 10N near
the coasts of N Colombia and Nicaragua. A recent scatterometer
satellite pass indicate that the strongest winds are mostly
confined from 11N to 14N and between 74W and 80W. The rest of the
Caribbean Sea experiences mainly gentle to moderate trades. Seas
of 8-10 ft are found in the south- central Caribbean, while 5-8 ft
are present in the north- central, E and SW Caribbean. Seas of
3-5 ft are prevalent in the NW Caribbean and Gulf of Honduras.

For the forecast, fresh to locally strong trade winds will
continue across the majority of central and SW Caribbean today and
tonight behind a tropical wave moving across Honduras. A tropical
wave will move across the tropical Atlantic waters today through
early Fri and weaken as it enters the E Caribbean Fri. A low level
disturbance accompanied by strong winds and very active weather
will enter the tropical Atlantic waters early Fri and reach the
central Lesser Antilles Fri morning before weakening as it moves
westward across the E Caribbean Fri through Sat. High pressure
will build N of the area late in the weekend and support mainly
moderate trades over the eastern half of the basin Sun through Mon
night.

ATLANTIC OCEAN...

A 1016 mb low pressure off the South Carolina coast is producing a
large area of showers and thunderstorms well to the E of the
center due to strong wind shear. The convection is mainly confined
to the N of 29N and between 70W and 78W. The National Hurricane
Center is tracking this system for possible tropical development
over the next few days and assesses a low chance of development
during the next 48 hours. Please visit the latest Tropical Weather
Outlook at hurricanes.gov for more details.

A surface trough extends from 28N53W to 19N66W and it is
interacting with a nearby upper level trough to produce a large
area of scattered moderate to isolated strong convection from 24N
to 30N and between 44W to 60W. Satellite-derived wind data
indicate that the strongest storms are producing fresh to strong
winds. A few showers are noted near the southern portion of the
trough axis. Another surface trough extends from 14N47W to 09N51W
and it is also under the favorable upper level dynamics provided
by the previously mentioned upper level trough. A large area of
scattered showers and isolated thunderstorms is noted from 11N to
20N and between 42W and 52W. The rest of the tropical Atlantic
enjoys fairly tranquil weather conditions.

Recent scatterometer satellite data show fresh to locally strong
trades from 09N to 19N and between 32W to 59W. Fresh to locally
strong NE winds are noted off the coast of Western Sahara from 18N
to 25N and E of 25W. Fresh trades are occurring from the NE coast
of Cuba to 26N and between 72W and 78W, including the E and
central Bahamas. Moderate to locally fresh winds are found
elsewhere in the tropical Atlantic. Seas of 7-10 ft are present S
of 20N and between 30W and the Lesser Antilles. Seas of 4-7 ft
are noted W of 60W and 5-8 ft prevail elsewhere.

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/.

For the forecast, the aforementioned low pressure off South
Carolina will drift NE and persist off the coasts of the
Carolinas through Sun. Some non-tropical development will be
possible over the weekend due to the system interacting with a
frontal boundary. Regardless of development, this system could
bring heavy rain to the offshore zones N of the Bahamas. Moderate
to fresh E winds S of 25N will continue through Fri and then
resume Sun into Mon night as high pres builds into the region and
both a tropical wave and low level disturbance move across the E
Caribbean.

$$
DELGADO
This weather bulletin was brought to you by:
www.nashvilleweather.net