[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 131029
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Wed Oct 13 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
1030 UTC.

...TROPICAL WAVES...

An Atlantic tropical wave has its axis along 28W, south of 18N
and it is moving W at 10-15 kt. Scattered moderate to isolated
strong convection is observed from 04N to 12N and between 27W and
31W.

Another Atlantic tropical wave has its axis along 49W/50W, south
of 18N and it is moving W at 15 kt. Scattered moderate to
isolated strong convection is noted where the wave interacts with
the ITCZ from 05N to 12N and between 48W and 52W. The northern
portion of the wave is surrounded by dry Saharan air and subsident
northerly flow aloft, suppressing the development of showers and
thunderstorms.

A Caribbean tropical wave has its axis along 65W, south of 20N,
extends from the Virgin Islands to E Venezuela, and it is moving
W at 10-15 kt. Scattered moderate to isolated strong convection is
seen on satellite imagery from 15N to 20N and between 63W to 65W.
Overnight scatterometer satellite pass show fresh to strong SE-S
winds within 170 nm to the E of the wave axis, mainly from 15N and
20N.

A second Caribbean tropical wave has its axis along 80W, south of
20N and it is moving W at 10-15 kts. No deep convection is noted
in association with the wave as it moves across very dry airmass.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends from the coast of Senegal near 11N16W to
05N30W. The ITCZ continues from 05N30W to 05N40W to 07N49W, then
continues W of a tropical wave near 05N51W to the coast of
Suriname near 06N54W. Scattered moderate convection is noted along
the monsoon trough from 04N to 09N between 15W and 28W. Scattered
moderate to isolated strong convection is noted along the ITCZ
from 06N to 10N between 33W and 54W.

...GULF OF MEXICO...

A weak ridge over the eastern United States extends to the Gulf of
Mexico and maintains tranquil weather conditions across the basin.
The pressure gradient between the ridge and lower pressures across
the southern United States and northern Mexico results in fresh SE
winds across the western Gulf waters, especially W of 94W. Seas in
this region are 3-6 ft. Moderate or weaker anticyclonic winds
with seas of 1-3 ft are prevalent elsewhere in the Gulf.

For the forecast, high pres extends extends weakly from the
eastern U.S. southwestward to the N central Gulf and will
influence the Gulf waters during the next several days. Moderate
to fresh southerly winds are expected over the western Gulf
between the ridge and lower pressure over the Southern Plains and
northern Mexico through Thu. Gentle to moderate breezes will
persist elsewhere through Fri. A cold front enter the NW Gulf Fri
night with fresh to strong northerly winds following it. The front
will reach central Florida to western Bay of Campeche Sun morning
with moderate to fresh N-NE winds across most of the Gulf.

...CARIBBEAN SEA...

An upper level trough off the SE United States extends to the NW
Caribbean Sea allowing for scattered showers and isolated
thunderstorms from the coast of Colombia to Hispaniola, between
70W and 70W. A surface trough extends from southern Florida to the
Gulf of Honduras and a few shallow showers are seen near the
trough axis. The rest of the basin remains fairly quiet outside of
the tropical wave in the E Caribbean previously described in the
Tropical Waves section. Fresh trades are noted within 150 nm of
the coast of NE Venezuela, including the waters surrounding the
ABC islands. Moderate or weaker trades prevail elsewhere. Seas of
3-5 ft are occurring in the E, central and SW Caribbean, while 1-3
ft are present elsewhere.

For the forecast, a tropical wave along 64W will move westward through
tonight, and spread fresh winds and very active weather across
the extreme NE Caribbean and adjacent Atlc waters. Northerly swell
will build across the regional Atlc and move through the
Caribbean passages through late Wed. Active weather associated
with an upper level trough along 59W will continue through Wed
morning. Low pres is expected to develop E of the southern Bahamas
on Thu and drift eastward into the weekend. This will weaken the
pressure gradient across the Caribbean basin leading to tranquil
marine conditions.

...ATLANTIC OCEAN...

Recent scatterometer satellite data depict a well-defined surface
trough extending from near the northern coast of Haiti to 28N71W.
This feature is interacting with an upper level trough located to
the west, producing a large area of scattered showers and isolated
thunderstorms, mainly from 20N to 31N and between 62W and 75W.
Satellite-derived wind data indicate fresh to strong cyclonic
winds within 100 nm of the coast of Hispaniola. The other feature
of interest in the tropical Atlantic is a 1004 mb low pressure
located just north of our area, but a surface trough extends south
to 24N46W. Scattered moderate convection is observed on satellite
imagery within 170 nm of the trough axis. Scatterometer satellite
data indicate fresh to strong cyclonic winds N of 28N and between
44W and 55W. Fairly tranquil weather conditions and moderate or
weaker winds prevail elsewhere in the basin.

Widespread northerly swell continues impact the region, reaching
8-11 ft mainly north of 15N between 30W and 65W. Seas of 5-8 ft
are found elsewhere.

The Cumbre Vieja volcano, that is on the island of La Palma in
the Canary Islands, has been erupting since 19 September 2021.
Currently, significant volcanic ash is seen in the vicinity of the
volcano drifting southward closer to the surface. Marine and
aviation interests should monitor this ongoing situation, by
reading the Volcanic Ash Advisory, that is issued by Meteo-France,
at http://vaac.meteo.fr/volcanoes/la-palma/.

For the forecast west of 65W, high pressure centered over the
central Atlantic will shift slowly E and weaken through the end of
the week. A low level trough extends from the southern Bahamas to
28N71W. Very active weather is expected with this trough through
Wed as it drifts eastward. Low pres may form along the trough by
Thu as it shifts E of 60W. Northerly swell across the regional
waters will peak tonight E of 70W then begin to fade Wed.

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