Tropical Weather Discussion

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Tropical Weather Discussion (NHC/TPC):
NWS National Hurricane Center Miami FL
0005 UTC Mon Sep 20 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=20
2050 UTC.=20

...SPECIAL FEATURES...

Tropical Storm Peter is centered near 18.4N 57.8W at 19/2100 UTC
or 300 nm E of the Northern Leeward Islands moving WNW at 15 kt.
Estimated minimum central pressure is 1007 mb. Maximum sustained
wind speed is 40 kt with gusts to 50 kt. Peak seas are currently
to 15 ft. Peter is a sheared tropical storm, however new deep=20
convection has developed in the past few hours closer to the=20
center. Scattered moderate to strong convection is noted within=20
240 nm in the northeast semicircle. An outer band of scattered
moderate convection is noted between 240 nm and 420 nm in the
northeast semicircle. A turn to the northwest is expected to=20
occur by Wed. On the forecast track, the center of Peter is=20
expected to pass well north of the Leeward Islands on Mon and Tue.
Even so, rainfall around the southern periphery of Tropical Storm
Peter may lead to areas of urban and small stream flooding from=20
late today into Tue. across Puerto Rico, the Virgin Islands, and=20
the Northern Leeward Islands. Some slight weakening is expected on
Mon. Please read the latest NHC Public Advisory at=20
https://urldefense.com/v3/__https://www.nhc.noaa.gov/text/MIATCPAT1.shtml__=
;!!DZ3fjg!oVr5kR00KkMEyIxIH0aEDuMenwoFsQvxhbb3LGevDZLfyKGw3iW0LR-FIjvHgYSw2=
GPKGzY8$  and Forecast/=20
Advisory at https://urldefense.com/v3/__https://www.nhc.noaa.gov/text/MIATC=
MAT1.shtml__;!!DZ3fjg!oVr5kR00KkMEyIxIH0aEDuMenwoFsQvxhbb3LGevDZLfyKGw3iW0L=
R-FIjvHgYSw2AXjOyoW$  for more
details.

Tropical Storm Rose is centered near 14.3N 29.9W at 19/2100 UTC
or 320 nm W of the Southernmost Cabo Verde Islands moving NNW at
14 kt. Estimated minimum central pressure is 1005 mb. Maximum
sustained wind speed is 35 kt with gusts to 45 kt. Peak seas are
currently 8 to 9 ft. Scattered moderate to strong convection is
noted within 210 nm in the northwest semicircle of Rose. A motion
toward the northwest is forecast to begin by tonight and continue
through Wed. Some strengthening is expected through Mon. By Tue,=20
environmental conditions are expected to become less conducive,=20
and Rose is forecast to begin a slow weakening trend.
Please read the latest NHC Public Advisory at=20
https://urldefense.com/v3/__https://www.nhc.noaa.gov/text/MIATCPAT2.shtml__=
;!!DZ3fjg!oVr5kR00KkMEyIxIH0aEDuMenwoFsQvxhbb3LGevDZLfyKGw3iW0LR-FIjvHgYSw2=
Jo1yB64$  and Forecast/=20
Advisory at https://urldefense.com/v3/__https://www.nhc.noaa.gov/text/MIATC=
MAT2.shtml__;!!DZ3fjg!oVr5kR00KkMEyIxIH0aEDuMenwoFsQvxhbb3LGevDZLfyKGw3iW0L=
R-FIjvHgYSw2B2o56F_$  for more
details. For sea conditions near this system, please read the=20
Meteo- France High Seas Forecast at: https://urldefense.com/v3/__http://wea=
ther.gmdss.org/II.html__;!!DZ3fjg!oVr5kR00KkMEyIxIH0aEDuMenwoFsQvxhbb3LGevD=
ZLfyKGw3iW0LR-FIjvHgYSw2J_VKaQc$=20

...TROPICAL WAVES...

A tropical wave is in the Atlantic Ocean along the west coast of
Africa along 16W/17W, from 02N to 20N, moving west at around 10
kt. Scattered moderate and isolated strong convection is noted
from 06N to 10N between 18W and 23W. Scattered moderate convection
is noted from 12N to 19N between 21W and 24W.

A tropical wave is in the Atlantic Ocean near Tropical Storm Rose
along 31W and 32W, from 02N to 19N, moving west at around 10 kt.
Scattered moderate and isolated strong convection is noted from
02N to 06N between 33W and 37W. Environmental conditions appear=20
conducive for gradual development over the next several days, and=20
a tropical depression could form late this week as it moves=20
westward at 10 to 15 kt across the eastern and central tropical=20
Atlantic Ocean.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends across the Senegal coast at 12.5N17W=20
through Tropical Storm Rose to to 06N39W. The ITCZ continues
from 06N39W to and to 08N46W. Scattered moderate convection is
noted from 04N to 07N between 40W and 42W.

The eastern Pacific monsoon trough extends into the SW Caribbean=20
Sea from western Panama near 09N82W to the northwest coast of=20
Colombia where 1010 mb low pressure is located at 11N75W.=20
Scattered moderate convection is noted from 09N to 11N between
80W and 83W.

...GULF OF MEXICO...

A surface trough persists across the northern and west-central
Gulf from northern Florida along 29N to 26N94W to the coast of=20
Mexico just north of Tampico near 23N98W. Scattered showers and
thunderstorms are noted near the trough, mainly from 25N to 30N
between 84W and 95W. Another surface trough is located in the
western Bay of Campeche from 23N97W to 18N94W with only isolated
showers or thunderstorms noted near the trough. The rest of the=20
basin enjoys fairly tranquil weather conditions under 1017 mb high
pressure centered near 26N83W. Mainly gentle to moderate
anticyclonic winds are noted across the basin, except light to
gentle NW winds west of the elongated trough. Seas are mainly 3=20
ft or less across the basin, except locally 4 ft in the central=20
Gulf near any convection.

For the forecast, weak high pressure will extend across the=20
eastern and central Gulf of Mexico through Tue. This pattern will=20
support continued gentle to moderate winds and mostly slight seas=20
across the Gulf. An early season cold front is expected to enter=20
the NW Gulf early Wed and reach from the NE Gulf to central Bay of
Campeche by late Thu.

...CARIBBEAN SEA...

Refer to the Special Features section above for details on
Tropical Storm Peter which is forecast to track well north of the
Leeward Islands on Mon and Tue.

Fairly tranquil marine conditions are noted across the basin other
than a few showers on the trade wind flow, and isolated
thunderstorms near the Greater and Lesser Antilles due to
afternoon heating. Moderate trades are noted west of 70W with
gentle trades east of 70W. Seas are 3 to 5 ft in the eastern
Caribbean, 4 to 7 ft in the central Caribbean, and 3 to 5 ft in
the western Caribbean.

For the forecast, Tropical Storm Peter is expected to continue=20
WNW and reach near 20N62W Mon afternoon, then gradually veer more
NW and reach near 22N 66W Tue afternoon, then turn northward=20
toward Bermuda throughout the rest of the week. As this occurs,=20
trade winds over the south-central Caribbean will diminish=20
through Thu night. Look for associated squalls and thunderstorms=20
to affect the Leeward Islands and adjacent waters this evening=20
through Tue.=20

...ATLANTIC OCEAN...

Please read the Special Features section above for details on=20
Tropical Storm Peter east of the Leeward Islands and Tropical=20
Storm Rose west-southwest of the Cabo Verde Islands.

The Cumbre Vieja volcano in the island of La Palma in the Canary=20
Islands erupted around 1410 UTC. The ash plume is expected to=20
remain below 5000 ft and drift SE, causing a reduction in=20
visibility. Mariners should exercise caution.

The surface trough over the northern Gulf of Mexico spills into=20
the Atlantic waters off the NE coast of Florida along 29N,=20
resulting in scattered moderate convection from 23N to 31N and=20
between 76W and the coasts of Florida and Georgia. An upper=20
level low near 23N64W is interacting with a surface trough that=20
extends from 26N59W to 20N61W, causing scattered moderate and=20
isolated strong convection from 18N to 27N and betwen 58W and=20
65W. The rest of the tropical Atlantic is dominated by a strong=20
subtropical ridge anchored near the Azores, maintaining fairly=20
tranquil weather conditions.=20

Light to gentle anticyclonic winds are noted from 27N to 31N,
except gentle to moderate north of 30N between 55W and 65W. Gentle
to moderate trades prevail elsewhere west of 40W outside of the
influence of Tropical Storm Peter. Moderate to fresh winds prevail
east of 40W outside of the influence of Tropical Storm Rose. Seas
are in the 5 to 8 ft range east of 60W, and 3 to 6 ft west of 60W.

For the forecast west of 55W, Tropical Storm Peter is expected to
continue WNW and reach near 20N62W Mon afternoon, then gradually=20
veer more NW and reach near 22N66W Tue afternoon, reach near
24N68W Wed afternoon, then turn northward toward Bermuda=20
throughout the rest of the week. Elsewhere west of 70W, gentle to=20
moderate winds and slight to moderate seas will persist over open=20
waters through the early part of the week, with swell to 8 ft=20
associated with the tropical storm reaching the waters east of 72W
by Wed.=20

$$
Graphical representation of waves, etc. on this image (NCEP/OPC) [more].
Various tropical satellite imagery available here

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