[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212321
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Wed Sep 22 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 downgraded to a Tropical Depression at 21/2100 UTC. At
this time, it is centered near 20.5N 65.0W or 140 nm NNE of San
Juan Puerto Rico moving WNW at 7 kt. Estimated minimum central
pressure is 1009 mb. Maximum sustained wind speed is 30 kt with
gusts to 40 kt. Numerous moderate to isolated strong convection
can be found within 120 nm NE and 90 nm SW semicircles of center.
Seas to 12 ft are within 60 nm NE quadrant of Peter. On the
forecast track, the center of Peter will remain well north of the
Virgin Islands and Puerto Rico tonight and should move well east
of the southeastern Bahamas during the next few days. Additional
gradual weakening is forecast over the next several days, and
Peter could degenerate into a remnant low by Thursday. Rainfall
around the southern periphery of Tropical Depression Peter could
produce additional rainfall totals of 1 to 4 inches, with storm
total accumulations up to 6 inches, across portions of the
Northern Leeward Islands, including portions of the Virgin
Islands, as well as Puerto Rico and the northern portions of
Hispaniola through Thursday morning. This rainfall may lead to
areas of urban and small stream flooding. Swells generated by
Peter are affecting the northern Leeward Islands and Puerto Rico,
and will continue spreading westward to Hispaniola this evening
and the Bahamas on Wednesday. These swells could cause life-
threatening surf and rip current conditions. 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 Peter NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

Tropical Storm Rose is centered near 22.5N 37.7W at 21/2100 UTC
or 870 nm WNW of the Cabo Verde Islands moving NW at 9 kt.
Estimated minimum central pressure is 1008 mb. Maximum sustained
wind speed is 35 kt with gusts to 45 kt. Seas to 12 ft are within
90 nm NE quadrant of Rose. Due to shear, only a small cluster of
deep convection is noted in the eastern quadrant of the storm.
The storm should gradually turn toward the north during the next
couple of days and move more to the northeast on Friday. Rose
could decay into a tropical depression this evening and
degenerate into a remnant low 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 Rose NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

A small but concentrated area of showers and thunderstorms is
redeveloping just N of a 1010 mb low pressure located near
09.5N28.5W or a few hundred miles southwest of the Cabo Verde
Islands. This low pressure is along a tropical wave with axis
near 28W/29W. Environmental conditions are expected to become
more conducive for development, and a tropical depression is
likely to form by Thursday or Friday while the system moves
westward at 10 to 15 kt across the eastern and central tropical
Atlantic Ocean. The latest Tropical Weather Outlook gives this
system a medium chance of tropical cyclone formation through 48
hours and a high chance through 5 days. Please, refer to the
Tropical Weather Outlook at www.hurricanes.gov for more details.

...TROPICAL WAVES...

A tropical wave is along 28W from 16N southward, moving west at
10 to 15 kt. Please, see the Special Features section for more
details.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the coastal plains of Senegal
near 14N17W to a 1010 mb low pressure located near 09.5N28.5W to
08N32W. The ITCZ continues from 08N32W to 07N40W to the coast of
Suriname near 06N55W. No significant convection is noted along
the monsoon trough or ITCZ.

GULF OF MEXICO...

Weak high pressure of 1018 mb centered near 26N90W dominates the
Gulf waters. This system continues to support gentle to moderate
winds and mostly slight seas across the region. Showers with
embedded thunderstorms are noted over the most of Florida Peninsula.
Plenty of moisture in a southerly wind flow will persist tomorrow
over South Florida keeping the likelihood of more showers and
thunderstorms. A diffluent pattern aloft is also helping to induce
this convective activity.

For the forecast, an early season cold front is expected to enter
the NW Gulf early Wed and reach from the NE Gulf to central Bay
of Campeche by late Thu before stalling, supporting increased
winds and seas over the northwest and north-central Gulf Tue
night through Thu. Moderate to fresh N-NE winds and seas of 6-8
ft are expected near the Tampico area Wed through Thu. Fresh to
strong NW winds and seas up to 8 ft are also expected near the
Veracruz region on Thu. Of note, this cold front is forecast to
support the first gap wind event, with minimal gale force
northerly winds in the Tehuantepec region Wed night into Thu
morning.

CARIBBEAN SEA...

Please read the Special Features section above for details on
Tropical Depression Peter which could degenerate into a remnant
low by Thursday.

An upper-level trough extends from eastern Cuba to near Cabo Gracias
a Dios, Nicaragua. On the W side of this trough, strong N-NE winds
continue to enhance scattered showers and thunderstorms over most
of Cuba. Convection has also flared-up over the Yucatan Peninsula
and northern Guatemala. The most recent scatterometer data indicate
fresh to locally strong trade winds near the coast of Colombia,
and moderate to fresh NE-E winds south of Hispaniola. Gentle to
moderate winds are noted elsewhere. Seas are 3 to 5 ft with the
strongest winds, and 2-3 ft elsewhere. Seas of 4 to 5 ft are
noted across the Caribbean passages of the NE Caribbean in
association with swells generated by Peter.

For the forecast, gentle to moderate trade winds will persist
across the basin during the next several days as Peter continues
to move away from the NE Caribbean.

ATLANTIC OCEAN...

Please read the Special Features section above for details on
Tropical Depression Peter, located about 140 nm NNE of San Juan,
Puerto Rico, Tropical Storm Rose situated about 870 nm WNW of
the Cabo Verde Islands, and a low pressure located near 9.5N28.5W
with potential of tropical cyclone formation.

The Cumbre Vieja volcano on the island of La Palma in the Canary
Islands has been erupting since 19/1410 UTC. Satellite imagery
shows volcanic ash approximately 30 nm W of the volcano as well
as the hot spot related to the eruption. 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 22/0300 UTC.

A cold front enters the forecast area near 31N47W then continues
SW and W to near 28N70W to 27N56W to 28N70W where it becomes
stationary to near Georgia/South Carolina border. Scattered
showers and thunderstorms are affecting the NW Bahamas and the
waters E of Florida to about 75W. Isolated showers and
thunderstorms are near the frontal boundary between 60W and 70W.
A ridge dominates the Atlantic waters E of 35W, including the
Azores, Madeiras and Canary Islands. The pressure gradient
between this ridge and T.S. Rose is producing an area of fresh to
strong E to SE winds within about 300 nm NE of Rose's center.
Fresh to strong NE winds are noted off southern Morocco and
Mauritania to near 22W.

For the forecast west of 65W, gentle to moderate winds and slight
to moderate seas will continue through late Wed night, except
for moderate to fresh winds between the Bahamas and Cuba and
elsewhere between 65W and 70W. Winds will then become light and
variable west of 70W through the weekend. A weak cold front will
move across the waters east of NE Florida Thu and stall through
Sun.

A gale-force, non-tropical low pressure system, the remnants of
Odette, is located about 700 miles west-northwest of the westernmost
Azores. This low could acquire some subtropical characteristics over
marginally warm waters during the next few days while it executes a
small cyclonic loop over the north-central Atlantic Ocean. However,
by the end of the week, this system is expected to encounter more
hostile environmental conditions. Additional information on this
system, including gale warnings, can be found in High Seas
Forecasts issued by the National Weather Service.

$$
GR
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