[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 222317
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 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 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...SPECIAL FEATURES...

Peter is expected to become a remnant low soon. At 22/2100 UTC,
Tropical Depression Peter is centered near 21.7N 66.7W or 200 nm
N of San Juan Puerto Rico moving NNW at 4 kt. Estimated minimum
central pressure is 1008 mb. Maximum sustained wind speed is 30
kt with gusts to 40 kt. The convection continues to be located
well to the east of the center due to vertical shear. The
depression is moving toward the north-northwest. A similar motion
with gradual turn to the north is expected tonight followed by a
turn toward the north-northeast tomorrow. Gradual weakening is
expected during the next couple of days, and Peter is forecast to
degenerate into a remnant low tonight or tomorrow. Please, read
the read the latest HIGH SEAS FORECAST issued by the National
Hurricane Center at website- https://www.nhc.noaa.gov/text/
MIAHSFAT2.shtml and the latest Peter NHC Forecast/Advisory and
Public Advisory at www.hurricanes.gov for more details.

Tropical Depression Rose is centered near 24.2N 40.2W at 22/2100
UTC or 1030 nm WNW of the Cabo Verde Islands moving WNW at 9 kt.
Estimated minimum central pressure is 1010 mb. Maximum sustained
wind speed is 30 kt with gusts to 40 kt. Rose is a swirl of low-
level clouds, with the only significant convection occurring
about 120 nm southeast of the center. The depression is moving
toward the west-northwest. A northwestward motion is expected
tonight, with a turn toward the north forecast by Thursday night.
A motion toward the northeast is expected on Friday. Gradual
weakening is forecast during the next couple of days, and Rose
is expected to degenerate to a remnant low pressure area on
Thursday or Thursday night. Please, read the latest HIGH SEAS
FORECAST issued by the National Hurricane Center at website-
https:/www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Rose
NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov
for more details.

Another Tropical Depression has formed in the eastern Atlantic,
and it is expected to strengthen over the next several days. The
depression is forecast to become a tropical storm (named Sam) by
tomorrow, and could be near hurricane intensity by the weekend.
At 22/2100 UTC, Tropical Depression Eighteen is centered near
10.1N 33.9W moving W at 13 kt. Estimated minimum central pressure
is 1008 mb. Maximum sustained wind speed is 30 kt with gusts to
40 kt. The depression is moving toward the west and this motion
is expected to continue for the next day or so followed by a
gradual turn to the west-northwest by Friday. Please, read the
latest HIGH SEAS FORECAST issued by the National Hurricane Center
at website- https:/www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the
latest T.D. Eighteen 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 more than 500 miles west-northwest of the
westernmost Azores. This low is beginning to develop more
concentrated shower activity and could become a subtropical or
tropical cyclone as it moves slowly across marginally warm waters
over the north-central Atlantic Ocean during the next several days.
However, by the weekend, this system is expected to move south into
an environment of strong upper-level winds. Additional information
on this system, including gale warnings, can be found in the
latest High Seas Forecast issued by the Ocean Prediction Center
at website-
https://ocean.weather.gov/mobile/mobile_product.php?=idNFDHSFA1.
This system has a medium chance of subtropical or tropical
cyclone formation through 48 hours. Please, see the latest
Tropical Weather Outlook at www.hurricanes.gov for more details.

...TROPICAL WAVES...

At this moment, no tropical waves are in the analysis/surface
map between W Africa and the Lesser Antilles, and across the
Caribbean Sea.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal plains of Senegal
near 14N17W then continues SW and W to 10N33W to 08N40W. The
ITCZ extends from 08N40W to 09N50W to NE Venezuela. No significant
convection is noted along the monsoon trough or ITCZ.

GULF OF MEXICO...

An early season cold front is moving across the Gulf region and
extends from the Florida panhandle to near Tampico, Mexico. Fresh
to strong northerly winds are noted per scatterometer data in the
wake of the front. Scattered showers with embedded thunderstorms
are observed along the frontal boundary. Similar convective
activity is seen once again across the Florida Peninsula. Plenty
of moisture in a southerly wind flow will persist over South Florida
on Thu, keeping the likelihood of more showers and thunderstorms.
A diffluent pattern aloft is also helping to induce this convective
activity.

For the forecast, the cold front will continue to move southeastward
through Thu, 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 over the northwest and
north-central Gulf into tonight. Fresh to strong winds will funnel
along the coast of Veracruz Thu, with seas building to 9 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. Of note, this cold front will support the first gap wind
event, with minimal gale force northerly winds, in the Tehuantepec
region tonight into Thu morning.

CARIBBEAN SEA...

Please read the Special Features section above for details on
Tropical Depression Peter located about 200 nm N of San Juan
Puerto Rico.

An upper-level trough extends from eastern Cuba to near Cabo Gracias
a Dios, Nicaragua. A diffluent pattern aloft, on the W side of
this trough, continues to enhance scattered to numerous showers
and thunderstorms over Cuba, including the Isle of Youth as well
as over the Yucatan Peninsula and northern Guatemala. Strong
southwesterly flow on the E side of the same trough is helping to
induce convection over most of Hispaniola. Showers and thunderstorms
have also flared-up over northern Colombia and parts of Panama,
Costa Rica and Nicaragua. The eastern extent of the eastern Pacific
monsoon trough is also contributing to the development of this
convection. Gentle to moderate winds prevail across the basin
with seas generally of 2-4 ft. Seas of 3-4 ft are noted across
the Caribbean passages.

For the forecast, newly formed Tropical Depression Eighteen well
east of the area is forecast to gradually strengthen to a hurricane
as it reaches near 53W on Mon. Expect for trades winds to increase
and seas to build over the far eastern part of the tropical north
Atlantic waters beginning Mon. Meanwhile trade winds over the south-
central Caribbean will diminish through Thu night. Fresh trade
winds will expand westward in coverage from the eastern Caribbean
to the western Caribbean from late Fri through the weekend, then
diminish over the western Caribbean early next week.

ATLANTIC OCEAN...

Please read the Special Features section above for details on
Tropical Depression Peter, Tropical Depression Rose, and newly
formed Tropical Depression 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 23/0300
UTC.

A stationary front extends from 31N43W to 27N60W to 28N75W to the
coast of South Carolina. Scattered showers are along the frontal
boundary. E of the front, a ridge continues to dominate the Atlantic
waters E of 35W, including the Azores, Madeiras and Canary Islands.
Mainly light to gentle NE to E winds are observed per satellite
derived wind data under the influence of the ridge. Moderate to
fresh NE winds are noted off southern Morocco and Mauritania to
near 22W.

For the forecast west of 65W, a 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 Fri, then dissipate
through early Sat evening.

$$
GR
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