[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 042054
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Tue Oct  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
2030 UTC.

...SPECIAL FEATURES...

Hurricane Sam is centered near 45.1N 42.5W at 04/2100 UTC or 450
nm E of Cape Race, Newfoundland, moving NE at 31 kt. Estimated
minimum central pressure is 965 mb. Maximum sustained wind speed
is 80 kt with gusts to 100 kt. Peak seas are near 48 ft and seas
of 12 ft or greater extend out up to 690 nm mainly SW of the
center. Numerous moderate to isolated strong convection is noted
up to 90 nm from the center, with scattered moderate convection
noted within 180 nm of the center, mainly in the NW quadrant. The
quick northeast forward speed is expected to continue overnight
with a slowly likely to commence Tue as Sam begins to merge with
an non-tropical low pressure system. Gradual weakening is expected
tonight but an approaching mid-latitude trough should result in a
rapid transition into a powerful extratropical cyclone by Tue.
Hurricane-force winds will likely continue after this transition,
into Tue night. Large swell continues to be generated by Sam
spreading in all directions, with the S edge of this swell
reaching as far S as 28N. Please read the latest High Seas
Forecast issued by the Ocean Prediction Center at the website
https://ocean.weather.gov/mobile/mobile_product.php?id=NFDHSFAT1
and the latest NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

A strengthening 1027 mb Azores high is generating near-gale NNE
to NE winds near the Canary Islands. For more information, please
read the METEO-FRANCE high seas forecast at the following website,
http://weather.gmdss.org/II.html

...TROPICAL WAVES...

An Atlantic tropical wave is along 32W from 19N southward, moving
W at around 15 kt. Scattered moderate to isolated strong
convection is seen from 04N to 10N between 28W and 38W.

A Caribbean tropical wave is near 76W from 17N southward into N
Colombia, and moving W at 10 to 15 kt. Aided by divergent flow
aloft, scattered moderate convection is occurring over the
central and N central Caribbean Sea, including Jamaica and S
Hispaniola.

...MONSOON TROUGH/ITCZ...

A modest monsoon trough passes through the coast of Mauritania
near 18N16W to just E of the Cabo Verde Islands at 17N21W. The
ITCZ extends from 07N21W to 06N30W and from 05N33W to 04N42W.
Scattered moderate convection is noted within 150 nm on both sides
of the ITCZ axis.

The eastern end of the E Pacific monsoon trough that extends along
10N from Costa Rica to Colombia in the SW Caribbean is triggered
numerous moderate to isolated strong convection in the area,
including the Nicaragua coast.

...GULF OF MEXICO...

A weak cold front has stalled this afternoon in the NW Gulf, from
the central Louisiana coast to just S of the Texas-Mexico border.
 This feature is producing scattered showers and isolated
thunderstorms over the N central and NW Gulf. Convection over and
near the Florida Panhandle is being enhanced by a surface trough
that has formed ahead of the stationary front, from Mobile Bay
southward to around 28N. A trough previously over the central Bay
of Campeche has dissipated, and associated convection has
diminished this afternoon. Weak surface ridging dominating the
basin is leading to mainly light to gentle winds and seas of 1 to
3 ft. Some moderate NE winds are occurring offshore the western
Yucatan Peninsula, and locally moderate NE winds are also present
behind the stalled frontal boundary offshore the lower Texas
coast.

For the forecast, a weak ridge north of the Gulf along 30N will
move eastward through Wed, supporting tranquil conditions across
all but the southeast sections of the basin, where moderate trades
will prevail. A front will remain nearly stationary over the NW
Gulf into mid-week.

...CARIBBEAN SEA...

Convergent trades are producing scattered showers and a few
thunderstorms along the coast of Belize and Honduras, and adjacent
waters. Refer to the Tropical Waves and Monsoon Trough/ITCZ
sections for additional convection in the basin.

Tightening gradient between the Bermuda high and E Pacific monsoon
trough is generating strong trade winds with seas of 7 to 10 ft
across the central basin. Fresh trades and seas at 6 to 8 ft are
evident over the E basin. Gentle to moderate trades and seas of 3
to 5 ft prevail for the rest of the basin.

For the forecast, high pressure off of the mid Atlantic coast
will gradually slide towards the east through the middle of the
week. This pattern will produce fresh to strong trade winds across
the NE and central Caribbean through Tue night. Fresh to strong
trade winds will then persist across the central Caribbean through
Thu. Moderate N to NE swell will affect the tropical Atlc waters
through Wed.

...ATLANTIC OCEAN...

See Special Features Section above for details on Hurricane Sam
and near-gale conditions in the eastern Atlantic near the Canary
Islands.

The remnants of Tropical Depression Victor have opened into a
trough that stretches from 24N45W to 15N45W. Fresh east winds and
seas of 8 to 10 ft are within about within about 90 nm of this
trough on both sides of the axis. A cluster of moderate convection
is noted in association with this trough, from 20N to 23N between
41W and 47W. This trough will gradually weaken as it moves WNW
over the next couple of days.

A deep layer trough from the SE Bahamas northward to SE and
offshore of the North Carolina coast is producing a large area of
scattered showers and thunderstorms from Hispaniola to 30N,
between 65W and 72W. Upper-level winds are not expected to be
favorable for significant development of this system will it moves
slowly NW over the next several days.

Aside from the convection associated with the aforementioned
troughs, showers and thunderstorms are associated with the
tropical wave and ITCZ and is described in the respective
sections above.

The Cumbre Vieja volcano, that is on the island of La Palma in
the Canary Islands, has been erupting since 19 September at 1410
UTC. An ash cloud reaching 10,000 ft or 3000 m is drifting
southward from the volcano. 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/

S of 25N, generally moderate to fresh trades prevail, with light
to gentle winds to the north. Locally strong NE winds are
occurring near the coast of NW Africa due to a tight pressure
gradient, otherwise the highest winds are fresh to locally strong
in the vicinity of the Leeward Islands. Seas are 6 to 8 ft,
although an area of 8 to 10 ft seas is located N of 25N between
40W and 60W.

For the forecast W of 50W, high pressure along the mid Atlc coast
will slide slowly eastward through mid week. This will produce
moderate to fresh trade winds south of 23N and east of the Bahamas
through Tue before spreading into the southeast Bahamas Wed
night. The swell generated from Hurricane Sam will continue to
impact the SW N Atlantic including the Bahamas through Wed. An
active weather pattern is expected across the waters E of 75W and
NE the Bahamas tonight through Tue as a surface trough becomes
better defined across the SE Bahamas and shifts slowly NW.

$$
KONARIK
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