[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 142246
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Fri Oct 15 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
2230 UTC.

...SPECIAL FEATURES...

Atlantic Gale Warning: A complex low pres system is developing
across the western Atlantic. A 1006 mb low pressure is located NE
of the Bahamas near 25N68W with a trough extending from it to a
1003 mb low near 26N63W. Scattered to numerous moderate
convection is from 20N-30N between 50W-65W. The lows are expected
to merge and deepen as it moves east and accelerates to the
northeast by Fri. Gale force winds are expected to develop south
of the new merged low by Fri 1200 UTC, from 25N-27N between 54W-
57W. The area of gale force winds will move east- northeastward,
moving N of the area by 1800 UTC on Saturday. Seas up to 13 ft
are expected within the area of gales.


Please read the latest High Seas Forecast issued by the National
Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml for more details.

...TROPICAL WAVES...

A tropical wave has been introduced to the analysis. The wave's
axis extends along 23W from 02N-18N, moving W at 10 to 15 kt.
Scattered showers are noted S of 14N between 20W-24W.

An Atlantic tropical wave has its axis along 39W S of 17N,
moving W at 15-20 kt. The convection in the vicinity of the wave
is mostly related to the proximity of the ITCZ, which extends
along 07N.

Another Atlantic tropical wave has its axis along 59W S of 17N,
moving W at 10 to 15 kt. Scattered moderate convection is noted
along the wave axis from 10N-13N.

A central Caribbean tropical wave axis extends along 73W from
05N-19N, moving W at 10-15 kt. Scattered moderate convection is
noted from 15N-20N between 70W-73W.

A western Caribbean tropical wave has its axis along along 85W
and N of 04N, moving W at 10 to 15 kt. Scattered showers are
noted from 05N to 12N between 87W and 87W.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends from the border of Guinea and
Guinea-Bissau near 11N15W to 08N23W. The ITCZ extends from 08N25W
to 08N37W, then continues W of a tropical wave from 07N41W to
10N55W. Aside from the convection mentioned in the tropical
waves section above, scattered moderate convection is noted from
06N-10N between 25W-52W.

GULF OF MEXICO...

Weak surface ridging covers most of the Gulf of Mexico. The
latest ASCAT data depicts gentle to moderate E winds covering
the area E of 93W, where seas are 2 to 4 ft. Relatively dry
conditions cover this area. Fresh SE to SSE winds are over the
far western Gulf of Mexico, W of 94W, confirmed by the latest
ASCAT data. Seas are 4 to 6 ft in this area. Strong
thunderstorms are noted along the coast of Texas between Freeport
and Corpus Christi. These storms are the result of remnant
moisture from East Pacific post-tropical Pamela, which
dissipated, and then combined with a weakening frontal
boundary/trough. These thunderstorms are expected to dissipate
by the evening hours.

The high pres will influence the Gulf waters during the next few
days. A cold front enter the NW Gulf Fri night with fresh to
strong northerly winds following it. The front will reach south
central Florida to western Bay of Campeche Sun morning with
moderate to fresh N to NE winds across most of the Gulf. Gale-
force N winds are possible across the Mexican waters Sat night
and are expected to develop off of Veracruz Sun morning through
afternoon.

CARIBBEAN SEA...

Refer to the section above for details on the tropical waves
moving across the basin.

An upper-level low centered near the central and northwest
Bahamas extends an upper-level trough SW to Honduras. Upper-
level divergence to the east of the upper-trough axis is
enhancing scattered showers and thunderstorms across most of the
basin between 60W-77W. The latest ASCAT data shows moderate SE
winds in the eastern Caribbean, where seas are 3 to 5 ft. ASCAT
shows gentle wind speeds in the western half of the basin, where
seas are 1 to 3 ft.

The upper level trough will persist from the Bahamas to the NW
Caribbean supporting active weather across the central and
extreme NE Caribbean through Fri. Low pres NE of the Bahamas will
shift E-NE through fri then accelerate NE into the weekend. This
will weaken the pressure gradient across the Caribbean basin
leading to tranquil marine conditions.

ATLANTIC OCEAN...

Please refer to the section above for details on the tropical
waves moving across the basin and the Gale Warning currently in
effect.

Aside from the convection related to the Special Features system
described above, the only area of scattered showers is noted in
the vicinity of a frontal boundary that extends from 31N34W to
27N42W to 1010 mb low near 29N50W to 31N59W. Latest ASCAT pass
from early depicted strong to near-gale force SW winds within
180 nm E of the front, mainly north of 28N and east of 37W,
where seas are likely 10 to 12 ft. A surface ridge axis extends
from 1021 mb high pressure near 39N13W to 1018 mb high near
24N30W to 20N55W. Gentle anticyclonic winds are near the ridge
axis.

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 ridge E of 60W will
shift E and weaken through the end of the week. Low pres system
near Bahamas will move E-NE tonight then accelerate NE and exit
the area on Fri. This system will continue to produce very active
weather and impact the regional waters through early Fri. A cold
front will move southeastward across Florida by the end of the
weekend, bringing fresh northerly winds off the Florida coast.

$$
ERA
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