[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122318
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 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 1800 UTC surface analysis and satellite imagery through
2200 UTC.

...TROPICAL WAVES...

An Atlantic tropical wave has its axis along 26W, south of 17N
and it is moving W at 10-15 kt. Scattered moderate to isolated
strong convection is observed from 06N to 14N and between 20W and
30W.

Another Atlantic tropical wave has its axis along 47W, south of
17N and it is moving W at 15 kt. A 12/1130 UTC scatterometer
satellite pass showed evidence of this tropical wave at the
surface. The northern portion of the wave is surrounded by dry
Saharan air and subsident northerly flow aloft, suppressing the
development of showers and thunderstorms. Scattered moderate
isolated strong convection is noted along the ITCZ near the wave
from 05N to 09N between 45W and 51W.

An eastern Caribbean tropical wave along 62W is moving westward
through the Leeward and Windward Islands at 10-15 kt. Scattered
moderate isolated strong convection is along the wave axis from
13N-17N and is affecting locations between St. Lucia and Antigua.
Additional scattered moderate convection from 14N-21N between
54W-60W is more related to an upper-level trough.

A Caribbean tropical wave extends from Jamaica to the
Panama/Colombia border, moving W at 10-15 kt. The wave is moving W
into a drier environment, and showers and tstorms have decreased
near the wave axis, and are mainly confined to areas over Panama
and N Colombia. Showers and tstorms E of the wave axis near Haiti
are more due to an upper low that is centered over central Cuba
near 22N78W.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends from the coast of Guinea-Bissau near
12N16W to 07N30W. A segment of the ITCZ continues from 07N30W to
07N46W, with another segment reaching from 07N49W to 09N59W.
Scattered moderate isolated strong convection is noted from 07N to
14N between 51W and 59W.

...GULF OF MEXICO...

A weak surface ridge extends from the southern Appalachians to
southern Mexico. A weak surface trough extends from South Florida
to the western Florida Straits to western Cuba. Isolated showers
and tstorms are along the trough. Dry conditions persist elsewhere
across the Gulf of Mexico, with no significant convection noted.
Moderate to fresh SE winds are noted over the far western Gulf,
between the ridge and lower pressure over Mexico. Seas are 4 to 6
ft in this area. Gentle easterly breezes and slight seas are noted
elsewhere.

For the forecast, the weak high pressure ridge 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 tonight through late Thu. Gentle to moderate breezes will
persist elsewhere through Fri. A cold front will enter the NW
Gulf Fri night and reach from central Florida to the western Bay
of Campeche Sun morning. Strong N winds and buildings seas are
likely behind the front.

...CARIBBEAN SEA...

A tropical wave is affecting the Lesser Antilles and far eastern
Caribbean. See the Special Features section above for details.

An upper-level low centered over central Cuba near 22N78W is
inducing a large area of scattered moderate isolated strong
showers and tstorms over the north-central Caribbean Sea, mostly
north of 17N, between Puerto Rico and eastern Cuba. A surface
trough extending from South Florida to western Cuba to 16N83W is
also inducing some showers and tstorms off the south coast of Cuba
from 20N to 22N between 80W and 82W. Farther south, near the north
coast of the Colombia/Venezuela border, numerous strong convection
is noted, mostly inland, from 09N to 12N between 72W-76W. This is
associated with the Colombia low along the eastern extension of
the east Pacific monsoon trough.

Moderate to fresh trades are over the eastern Caribbean, with seas
of 4 to 6 ft. Gentle winds and slight seas are evident across the
western half of the basin.

For the forecast, the tropical wave along 62W will move westward,
and spread fresh to strong winds and very active weather across
the extreme NE Caribbean and adjacent Atlc waters through tonight.
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 58W will continue
through Wed morning. Low pres is expected to form 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...

A broad mid to upper level low is over the north coast of central
Cuba near 22N78W. Associated divergent flow aloft is supporting a
large area of scattered moderate isolated strong convection from
18N-28N between 63W-74W. Moderate to fresh SE winds are evident
near an associated surface trough that reaches from near 28N72W to
the N coast of Haiti. Gentle to moderate E breezes are noted
elsewhere west of 65W.

A mid to upper-level trough extending from 25N55W to 17N58W is
supporting a disorganized area of showers east of the Leeward
Islands from 14N to 21N between 53W and 60W. Moderate to fresh SE
winds are observed east of the Leeward Islands, ahead of this
trough and following a tropical wave moving into the eastern
Caribbean.

A surface ridge extends across the subtropical Atlantic from near
Jacksonville Florida to a 1017 mb high pressure center near
29N66W to 23N50W to another 1017 mb high pressure center near
24N30W. This pattern is supporting mostly moderate to
occasionally fresh trade winds across the tropical Atlantic south
of 20N. Light to gentle breezes are present near the ridge axis.

A gale force 1007 mb low is centered just north of the area near
33N52W. This system is inducing thunderstorms north of 29N
between 46W-55W. Fresh to strong W winds are occurring in this
area. As this low moves eastward over the next 24 hours, expect
strong to near gale force SW to W winds to impact the area north
of 25N between 35W-55W, along with seas of 9 to 12 ft.

Widespread northerly swell continues impact the region, reaching
8 to 10 ft mainly north of 15N between 30W and 65W, with 5 to 8
ft seas noted 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, and eastward
higher up. 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 west of 65W, 1017 mb high pressure centered near
29N66W will shift slowly E and weaken through the end of the
week. A low level trough extends from 28N72W to the N coast of
Haiti. Very active weather is expected along and within 250 nm E
of 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 this evening through
tonight E of 70W then begin to fade Wed.

$$
Hagen
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