[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 301759
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sat Oct 30 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 1200 UTC surface analysis and satellite imagery through
1700 UTC.

...SPECIAL FEATURES...

Showers continue to show some signs of organization near a gale
force, frontal 986 mb low pressure system located near 39N49W, or
several hundred nm south-southeast of Cape Race, Newfoundland. The
low is moving SE near 15 kt. The low appears to be gradually
losing its frontal structure, and the system is likely to
transition to a subtropical storm by early next week while it
meanders over the central subtropical Atlantic. There is a medium
chance of development for this system within the next 48 hours.
Please read the latest Tropical Weather Outlook issued by the
National Hurricane center at www.hurricanes.gov and the latest
High Seas Forecast issued by the National Weather Service at
ocean.weather.gov/shtml/NFDHSFAT1.php for more details.

...TROPICAL WAVES...

An Atlantic tropical wave is along 32W from 18N southward and
moving W at 5 kt. No significant shower activity is associated
with the wave.

...MONSOON TROUGH/ITCZ...

A monsoon trough exits the coast of The Gambia near 13N17W to 1008
mb low pressure near 09N24W to 1011 mb low pressure near 08N31W
to 07N38W. Scattered moderate and isolated strong convection is
noted from 03N to 15N between the coast of Africa and 29W.

The 1008 mb low along the monsoon trough near 09N24W is being
monitored for potential tropical cyclone formation. The associated
shower and thunderstorm activity is showing signs of organization,
and environmental conditions could support some development of
this system during the next couple of days as it moves generally
northwestward at 10 to 15 kt. The chance of formation within the
next 48 hours is low. By the middle of next week, upper-level
winds are forecast to become increasingly unfavorable for further
development.

GULF OF MEXICO...

Isolated to scattered light showers associated with a reinforcing
surface trough are confined to the far eastern Gulf of Mexico,
east of 85W. Otherwise, a 1018 mb surface high pressure is
centered over the SW Gulf near 22N97W. The latest ASCAT pass from
the late morning hours on Saturday shows fresh W to NW winds
covering the eastern half of the Gulf of Mexico, locally strong in
the SE Gulf. Light to gentle winds are in the SW Gulf near the
high pressure. Wave heights in the SE Gulf, including the western
Florida Straits and Yucatan Channel, are likely currently in the
8 to 12 ft range. Elsewhere, seas are 4 to 7 ft.

For the forecast, moderate to fresh W to NW winds and choppy to
rough seas to the east of 93W will diminish this evening as a
cold front in the NW Caribbean continues to move slowly eastward.
Remaining NW swell will gradually subside to below 8 ft by Sun
morning. Fairly tranquil marine conditions are then forecast for
the rest of the weekend and continuing through the middle of the
upcoming week.

CARIBBEAN SEA...

A cold front extends from central Cuba near 22N78W to eastern
Nicaragua near 13N84W. A recent ASCAT pass shows fresh NW winds
covering the NW Caribbean to the west of the front. Seas are 5 to
8 ft in this area, except 9 to 12 ft in the Yucatan Channel.
Scattered moderate showers and isolated thunderstorms are along
the frontal boundary. The eastern end of the eastern Pacific
monsoon trough extends from 13N73W to the Costa Rica/Nicaragua
border. Scattered moderate and isolated strong convection is noted
south of 14N between 65W-85W. To the east, moderate trades
prevail over the eastern and central Caribbean, except for fresh
from 12N-17N between 68W-75W. Seas are 4-7 ft in the central
Caribbean, and 2-4 ft in the eastern and SW portions of the basin.

For the forecast, the cold front will move through the NW
Caribbean this weekend, before stalling Sun night from eastern
Cuba to the offshore waters of Nicaragua. Moderate to fresh NW
winds and seas of up to 8 ft can be expected in the wake of the
cold front, except up to 12 ft in the Yucatan Channel through
this afternoon. Elsewhere, a weak pressure gradient ahead of the
front will support mainly gentle to moderate trade winds across
the basin through the middle of next week, with locally fresh
winds off the coast of Venezuela today.

ATLANTIC OCEAN...

West of 65W: A slow moving cold front extends from 31N72W to the
central Bahamas near 25N76W to central Cuba near 22N78W. Scattered
moderate isolated strong showers and thunderstorms are firing
within 30 nm west and within 60 nm east of the front. A recent
ASCAT pass shows fresh to strong S-SW winds ahead of the front to
69W with fresh to strong SW to W winds west of the front, through
the NW Bahamas and Florida Straits as well as east of Florida.
Seas are 7 to 11 ft to the north and northeast of the Bahamas and
5 to 7 ft farther south, closer to Puerto Rico. The cold front
will move slowly east and reach from Bermuda to eastern Cuba by
Sun morning. Fresh to strong winds are expected on both sides of
the front through tonight, mainly north of 25N. Seas of 8 ft or
greater will continue to prevail north of 26N east of 78W, as well
as in the Florida Straits, lingering through Sun before decaying.
The front will weaken as it stretches from 30N65W to the Turks
and Caicos Islands Mon morning with gentle to locally moderate NE
flow then prevailing across the southern Bahamas and the Great
Bahama Bank into mid-week.

East of 65W: Another cold front extends from 31N45W to 27N52W.
Scattered moderate showers and thunderstorms and fresh to strong
SW winds are noted within 120 nm southeast of the front. Seas of 8
to 11 ft prevail on both sides of the front, north of 26N between
40W-60W. The cold front will reach from 31N40W to 26N45W by Sun
evening before slowing down. Fresh to strong SW winds and 8 to 12
ft seas will continue east of this boundary through early Tue.
Seas of 8 to 11 ft in N swell will also continue west of the front
during the next several days, mainly north of 27N. The subtropical
surface high pressure ridge extends from a 1021 mb high pressure
near 29N21W to a 1017 mb high pressure near 23N55W to 24N66W to
the Turks and Caicos Islands. Another high pressure of 1016 mb is
centered near 28N63W. Light to gentle winds are near the high
pressure ridges. Fresh NE trades are noted from 14N-21N between
the west coast of Africa and 32W. South of 26N, seas of 4 to 7 ft
prevail across the eastern and central Atlantic.

The Cumbre Vieja volcano, on the island of La Palma in the Canary
Islands, has been erupting since 19 September 2021. Recently,
there has been an increase in volcanic ash emission, with medium
to high ash concentration spreading up to 30 to 35 nm west of the
volcano. High volcanic ash concentration remains in the vicinity
of the volcano. Marine and aviation interests should monitor this
ongoing situation by reading the Volcanic Ash Advisory issued by
Meteo-France at website http://vaac.meteo.fr/volcanoes/la-palma/.

$$
Hagen
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