[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 150419
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 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 0000 UTC surface analysis and satellite imagery through
0425 UTC.

...SPECIAL FEATURES...

Atlantic Gale Warning: A broad 1004 mb low pressure is located
between the Leeward Islands and Bermuda near 26N63W with a warm
front extending to the east and a surface trough extending SW to
the SE Bahamas. A large area of showers and isolated thunderstorms
extends to the east and south of the low pressure, mainly from
20N to 28N and between 50W and 64W. Recent scatterometer satellite
data indicate that strong to near-gale force winds are already
occurring within 150 nm of the south of the center. The low is
forecast to deepen as it moves east- northeast and accelerates to
the northeast by Fri. Gale force winds are expected to develop
south of the 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...

An Atlantic tropical wave has its axis along 25W, south of 18N and
it is moving W at around 15 kt. Scattered moderate convection is
noted from 07N and 11N and 23W and 27W. A stable airmass N of 11N
suppresses the development of showers and thunderstorms.

Another Atlantic tropical wave has its axis along 40W, south of
18N, and it is moving W at around 15 kt. Scattered moderate to
isolated strong convection is noted from 05N and 11N and 37W and
43W. A stable airmass N of 11N suppresses the development of
showers and thunderstorms.

A third Atlantic tropical wave has its axis along 61W, south of
17N, extending across the Lesser Antilles into E Venezuela and N
Brazil, and it is moving W at around 15 kt. No deep convection is
observed near the wave axis. However, it is likely enhancing the
formation of showers over E Venezuela.

A Caribbean tropical wave has its axis along 74W, south of 19N,
extending from Haiti to N Colombia, and it is moving W at 10-15
kt. No deep convection is present near the wave axis. However, it
is likely enhancing the formation of showers and isolated
thunderstorms over N Colombia.

Another Caribbean tropical wave has its axis along 86W, south of
20N, extending across Honduras and W Nicaragua into the E Pacific
and it is moving W at 10-15 kt. Scattered moderate convection is
seen over Central America near the wave axis.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends from the coast of Guinea-Bissau near
11N16W to 05N20W. The ITCZ extends from 05N20W to 05N25W, then
continues W of a tropical wave from 05N26W to 05N39W. Another
segment then continues from 05N41W to the coast of French Guiana
near 06N54W. Scattered moderate to isolated strong convection is
noted within 300 nm of the ITCZ between 43W and 51W and also
between 37W to 27W. A few showers are observed near the monsoon
trough E of 21W.

GULF OF MEXICO...

The Gulf of Mexico remains in the southwestern periphery of a weak
ridge positioned over the eastern United States. A weak pressure
gradient results in moderate or weaker anticyclonic winds to
prevail across the basin. A weak surface trough located in the NE
Gulf along 87W from 26N to 29N is producing a few shallow showers.
The rest of the Gulf enjoys fairly tranquil weather conditions.
Seas of 3-5 ft are occurring W of 94W, while 1-3 ft seas are
present elsewhere.

For the forecast, the aforementioned high pres extending from the
eastern U.S. southwestward to the N central Gulf will influence
the Gulf waters during the next few days. A cold front will 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.

A deep upper level trough continues off the SE United States,
protruding into the NW Caribbean and reaching Central America, is
interacting with tropical moisture to produce a large area of
widespread shallow showers extending from Nicaragua to Hispaniola.
A surface trough extends from near Puerto Rico to near the low
pressure well north of the islands and a few showers and isolated
thunderstorms are observed near the trough axis, affecting parts
of Puerto Rico and the Virgin Islands. A weak pressure gradient
across the Caribbean Sea results in moderate or weaker trades in
the basin. Seas of 3-5 ft are occurring E of 75W and 1-3 ft seas
are present elsewhere.

For the forecast, an upper level trough extending from the Bahamas to
the NW Caribbean will support active weather across the central
Caribbean 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 low pressure system mentioned in the Special
Features section, the other feature of interest is a cold front
that enters the tropical Atlantic near 31N32W and becomes a
stationary front that continues to a 1009 mb low pressure near
29N48W. The stationary front then exits the tropical Atlantic near
31N61W. Scattered moderate convection is noted within 200 nm on
both sides of the frontal boundary. The strongest convection is
found N of 29N and between 28W and 33W. Scatterometer satellite
data indicate that fresh southerly winds are occurring with the
strongest convection. A surface trough NE of the NW Bahamas from
31N68W to 28N76W is producing a few showers near its axis. The
rest of the tropical Atlantic is dominated by a broad 1022 mb high
pressure located in the far NE Atlantic that stretches to the
Lesser Antilles.

Recent scatterometer satellite data depict fresh to strong trades
from 08N to 15N and between 30W and 44W. Fresh N winds are also
occurring E of 22W and from 18N to 24N, with the strongest winds
affecting the waters off Western Sahara and NW Mauritania. Seas
of 7-10 ft are found N of 24N and 27W and 40W. Seas of 5-8 ft
prevail to the W of 55W and 6-9 ft seas are prevalent S of 25N and
E of 55W. Seas of 4-7 ft are noted elsewhere in the basin.

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 55W, the aforementioned low pres 1004 mb
near 26N63W will move E-NE tonight then accelerate NE and exit the
area on Fri. This system will produce active weather that will
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.

$$
DELGADO
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