[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231045
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Thu Sep 23 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 0600 UTC surface analysis and satellite imagery through
1030 UTC.

...SPECIAL FEATURES...

Tropical Depression Eighteen is centered near 10.5N 36.4W at
23/0900 UTC or 1620 nm ESE of the Northern Leeward Islands
moving W at 13 kt. Estimated minimum central pressure is 1008
mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt.
Convection is becoming better organized within 120 nm in the
northwest semicircle of the center of the depression. Seas are
estimate to be reaching 10 ft currently, but will build throughout
today within 120 nm on the north side of the low as it continues
to move westward. The depression is expected continue to intensify
and reach tropical storm strength later today, and likely become
a hurricane Sat. Please read the latest the latest NHC
Forecast/Advisory and Public Advisory for T.S. Eighteen at
www.hurricanes.gov for more details.

Recently downgraded Post-Tropical Cyclone Rose is centered
near 25.2N 41.6W at 23/0900 UTC or 1130 nm WNW of the Cabo Verde
Islands moving NW at 9 kt. Estimated minimum central pressure is
1010 mb. The center remains fully exposed with no significant
convection noted in its vicinity. An earlier CryoSat-2 altimeter
pass indicated seas were still reaching near 12 ft within 120 nm
in the northeast quadrant of Rose. This is not really due to the
winds near Rose, and is actually due to a larger area of northerly
swell causing 8 to 12 ft seas north of 22N between 35W and 60W.
Rose will move more north tonight, then northeast through Fri,
before gradually dissipating through Sat. Please read the latest the
latest Rose NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov
for more details.

A gale-force, non-tropical low pressure system, the remnants of
Odette, is located about 600 miles west-northwest of the westernmost
Azores.  Showers and thunderstorms have increased a little near the
low, and there is a medium chance it could become a subtropical
or tropical cyclone while it moves generally southward over
marginally warmer waters during the next couple of days. Strong
upper-level winds are expected to develop over the system this
weekend, which should limit its development. Additional
information on this system, including gale warnings, can be found
in High Seas Forecasts issued by the Ocean Prediction Center
ocean.weather.gov. Also see the latest Tropical Weather Outlook
at www.hurricanes.gov for more details.

...TROPICAL WAVES...

A tropical wave is evident just east of the Cabo Verde Islands
along 21W from 05N to 20N. Scattered moderate convection is noted
from 03N to 07N east of 22W. Another tropical wave is analyzed
along 50W/51W south of 20N. No significant convection is noted
near the wave axis.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the the Senegalese coast near
15N17W to 08N25W to 08N30W. A segment of the ITCZ extends from
07N40W to 06N48W, and from 06N51W to 06N57W. Other than the
convection noted in the Tropical Wave section, no significant
convection is observed along the monsoon trough or in association
with the ITCZ.

GULF OF MEXICO...

An early season cold front is moving across the northern Gulf, and
currently extends from Crystal River, Florida to Poza Rica, Mexico.
Scatterometer satellite data along with recent buoy observations
indicate fresh to strong northerly winds are following the front.
This includes and area of fresh to strong NW winds just of the
Mexican coast near Tampico. Altimeter satellite data along with
recent buoy observations are showing seas building to 6 to 8 ft
behind the front. Light to gentle breezes and slight seas are
noted south of the front. Scattered moderate convection is noted
mainly along the coast of Mexico, south of 24N and west of 95W, as
well as a few thunderstorms along the front between 85W and 90W.

For the forecast, the front will continue to move southeastward
through tonight, stall from roughly Fort Myers, Florida to the
coast of Veracruz, Mexico near 18N95W Fri, then dissipate Sat.
Fresh to strong winds will follow the front into tonight,
including along the coast of Veracruz where seas may build to
8 ft. Looking ahead, winds and seas will diminish across basin
from Sat and into early next week as high pressure builds over
the northern Gulf.

CARIBBEAN SEA...

A sharp upper trough across eastern Cuba continues to support
scattered overnight showers and thunderstorms from the southern
peninsula of Haiti to Jamaica. Scattered showers and thunderstorms
are also evident north of the monsoon trough off the coast of
Colombia and eastern Panama. M

The thunderstorm activity that developed in the afternoon and
evening hours across the islands in the W Caribbean has generally
dissipated. Overall, no deep convection is noted across the
basin. However, showers and thunderstorms continue to affect parts
of Costa Rica, Panama and N Colombia, with most of convection on
their Pacific coasts. The weak pressure gradient due to the
remnants of Peter just north of basin and typical lower pressures
over South America results in gentle to moderate trades across the
region as observed in a recent scatterometer satellite pass. Seas
in the E Caribbean are 2-4 ft, and 1-2 ft elsewhere.

For the forecast, Tropical Depression Eighteen is well to the
east over the Tropical Atlantic near 10.2N 35.0W 1008 mb at 0300
UTC moving W at 13 kt. Maximum sustained winds 30 kt gusts 40 kt.
Eighteen will continue to intensify as it moves across the
Atlantic, becoming a hurricane near 12.5N 46.0W by Sat morning
and, reaching 55W east of the Leeward Islands by Mon. Meanwhile,
moderate trade winds will persist over much of the Caribbean into
early next week, becoming fresh over the south-central Caribbean
Sun and Mon.

ATLANTIC OCEAN...

Please read the Special Features section above for details on
the Remnants of Peter, and Tropical Depressions Rose and
Eighteen.

The Cumbre Vieja volcano on the island of La Palma in the Canary
Islands has been erupting since 19/1410 UTC. The volcano is still
emitting ashes, mainly around the volcano drifting SSW below
10,000 ft, and NE above 10,000 ft. Marine and aviation interests
should monitor this on-going situation by reading Volcanic Ash
Advisory issued by Meteo-France at http://vaac.meteo.fr/volcanoes
/la-palma/. The next advisory will be issue no later than 23/0900
UTC.

A stationary front extends from 31N44W to 27N60W to 31N78W to the
coast of South Carolina. An upper level low near Bermuda is
interacting with the frontal boundary and the tropical moisture
being propelled northward by the remnants of Peter, resulting in
scattered showers and a few thunderstorms from 24N to 31N and
between 55W and 68W. The E Atlantic remains under the influence of
a strong 1033 mb ridge positioned N of the Azores. Satellite-derived
wind data indicate fresh NE winds off the coast of Mauritania and
the surrounding waters of the Cabo Verde Islands, mainly from 16N
to 21N and E of 27W. This is associated with an outbreak of dry
Saharan air. Gentle to moderate anticyclonic winds prevail in the
rest of the basin. Seas of 3-6 ft are prevalent W of 60W and 4-7
ft E of 60W.

For the forecast west of 65W, the remnant low of Peter is near
22.1N 67.0W 1008 mb at 0300 UTC moving NNW at 4 kt. Maximum
sustained winds are 25 kt with gusts to 35 kt. This low will
continue to weaken as it drifts northeast of the region through
Sat cold front will move off the northeast Florida coast tonight,
continue to the southeast Thu, stall from 31N77W to near Fort
Pierce, Florida by late Thu, then dissipate through early Sun just
before a second weak front possibly moves into the region early
next week. Farther east, Tropical Depression Eighteen is over the
Tropical Atlantic near 10.2N 35.0W 1008 mb at 0300 UTC moving W at
13 kt. Maximum sustained winds 30 kt gusts 40 kt. Eighteen will
continue to intensify as it moves across the Atlantic, becoming a
hurricane near 12.5N 46.0W by Sat morning and, reaching 55W east
of the Leeward Islands by Mon.

$$
Christensen
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