[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 141034
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Thu Oct 14 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
1010 UTC.

...SPECIAL FEATURES...

Atlantic Gale Warning: A 1009 mb low is located NE of the Bahamas
near 24N70W with a trough extending along it from 28N65W to
21N70W. Scattered moderate convection is occurring along and east
of this system from 20N to 28N between 65W and 71W. This low is
expected to slowly drift east today and accelerate to the
northeast by Fri. By 16/0600 UTC, southwesterly gale force winds
are expected to develop south of the low, from 26N to 28N between
47W and 48W with seas building to 14 ft. As the low continues to
move farther to the northeast outside of the forecast waters, the
gale force winds will end by 16/1200 UTC. However, strong to near
gale- force winds are expected to persist through Sat night.
Please read the latest High Seas Forecast issued by the National
Hurricane Center at website
http://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details.

...TROPICAL WAVES...

An Atlantic tropical wave has its axis along 35W, south of 17N
and it is moving W at 10-15 kt. A few showers are noted near the
wave axis from 03N and 08N. Dry air is suppressing the storm
activity N of 10N.

Another Atlantic tropical wave has its axis along 55W, south of
17N and it is moving W at 10-15 kt. A few showers are observed
near the wave axis. However, dry air is suppressing the storm
activity N of 11N.

A Caribbean tropical wave has its axis along 70W, south of 19N,
extending from the Dominican Republic to W Venezuela and E
Colombia. The tropical wave is moving W at 10-15 kt. A few showers
are seen near the wave axis.

A second Caribbean tropical wave has its axis along 83W, south of
20N and it is moving W at about 10 kt. No deep convection is
noted in association with the wave as it moves into a dry airmass.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends from the coast of Guinea near 10N14W to
07N23W. The ITCZ continues from 07N23W to 07N34W, then continues W
of a tropical wave near 07N36W to the coast of French Guiana near
05N52W. Scattered moderate convection is noted near the monsoon
trough and ITCZ from 02N to 10N between 14W and 31W. Scattered
moderate convection is also noted near the ITCZ from 02N to 09N
between 34W and 47W.

...GULF OF MEXICO...

A 1018 mb high pressure system centered over the Mid-Atlantic
extends to the Gulf of Mexico. A surface trough is found near the
western coast of Florida and another one extends along 85W/86W
from 15N-25N. Only a few shallow showers are seen in association
with these troughs. The rest of the Gulf enjoys fairly tranquil
weather conditions. The pressure gradient between the weak ridge
and lower pressures across the southern United States and the
remnants of Pamela over N Mexico results in fresh to strong SE
winds W of 95W as shown in an overnight scatterometer satellite
pass and surface observations. Seas of 4-6 ft are noted W of 94W,
with the highest seas occurring off the S Texas and NE Tamaulipas
coasts. Moderate or weaker winds and seas of 2-4 ft prevail
elsewhere in the Gulf.

For the forecast, high pres 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 to NE winds across most of the Gulf. Gale-
force winds could develop off of Veracruz by Sun morning and
continue through the afternoon.

...CARIBBEAN SEA...

A sharp upper level trough and upper level low is located in the
NW Bahamas. This is enhancing the development of showers and
thunderstorms to the east of a surface trough that extends from
the NE Caribbean to well north of the Leeward Islands. The large
area of convection is mainly N of 15N between 62W and 67W. These
storms are impacting parts of Puerto Rico and the Virgin Islands.
Overnight scatterometer data indicate that fresh to strong
southerly winds are occurring in association with the strongest
convection. Moderate or weaker winds prevail in the rest of the
basin. The exception are locally fresh trades noted in between
Cuba and Jamaica and within 60 nm of the central coast of Cuba.
Seas of 3-5 ft are found E of 77W. Seas of 1-3 ft are prevalent
elsewhere in the Caribbean.

For the forecast, a vigorous upper level trough from the Bahamas to
the NW Caribbean will support active weather across the central
Caribbean and extreme NE Caribbean through Fri. Northerly swell
will subside across the regional Atlc and Caribbean passages
today. Low pres NE of the southern Bahamas will drift E-NE tonight
through Thu then accelerate NE into the weekend. This will weaken
the pressure gradient across the Caribbean basin leading to
tranquil marine conditions.

...ATLANTIC OCEAN...

See the Special Features section on the 1009 mb low NE of the
Bahamas that will bring gale force winds to the central Atlc.

The previously mentioned upper level low in the NW Bahamas
continues to interact with a couple of surface troughs further to
the east, producing a large area of showers and thunderstorms.The
first trough is explained in the Special Features section. The
other surface trough extends from 26N61W to 18N66W. Scattered
moderate to isolated strong convection is found from the NE
Caribbean to 29N and between 59W and 64W. Overnight scatterometer
satellite data indicate that fresh to strong southerly winds are
found with the strongest convection. Otherwise, light to gentle
winds prevail in this area.

The other feature of interest is a cold front that extends from a
996 mb low pressure system north of our area, entering the
tropical Atlantic near 31N38W and continues SW to 27N49W. The
front stalls from that point to near 31N59W. Scattered moderate
convection is noted from 24N to 31N between 33W and 48W. Overnight
satellite- derived wind data depict a large area fresh and strong
cyclonic winds N of 24N and between 31W and 48W. The rest of the
tropical Atlantic is dominated by a weak ridge centered near the
Madeira islands, permitting fairly tranquil weather conditions and
moderate or weaker winds.

A widespread northerly swell continues to impact the north-
central tropical Atlantic with seas of 8-12 ft, mainly N of 25N
and between 33W and 55W. Seas of 4-7 ft are found W of 60W, while
seas of 6-9 ft are noted S of 25N and W of 30W. Finally, seas of
5-8 ft are present E of 30W.

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

For the forecast W of 65W, high pressure extending across the
area will shift slowly E and weaken through the end of the week.
Developing low pres 1009 mb near 24N70W will begin to drift E-NE
today then accelerate E-NE and exit the area by Fri. This system
will continue to produce very active weather and impact the
regional waters through Fri. Northerly swell across the regional
waters will subside today. A cold front will move southward across
Florida by the end of the weekend, bringing fresh northerly winds
off the Florida coast.

$$
AReinhart
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