AXNT20 KNHC 191708
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sun Sep 19 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
Tropical Storm Peter is centered near 17.6N 56.5W at 19/1500 UTC
or 380 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. Peter is under strong SW
wind shear, displacing the convection well to the NE of the
center. Numerous moderate to isolated strong convection is
observed from 16N to 22N and between 50W and 55W. Peter is
producing up to 13 ft seas near the center. A gradual decrease in
forward speed is is expected through Tuesday. A turn to the
northwest is expected to occur by Wednesday. On the forecast
track, the center of Peter is expected to pass well north of the
Leeward Islands on Monday and Tuesday. Heavy rain and large swells
are expected to impact the N Leeward Islands, Virgin Islands and
Puerto Rico. Interests across these areas should monitor this
system closely. Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT1.shtml and Offshore Waters
Forecasts at www.nhc.noaa.gov/marine/offshores.php for
Tropical Depression Seventeen is centered near 13.2N 28.8W at
19/1500 UTC or 275 nm WSW of the southernmost Cabo Verde Islands
moving NNW at 12 kt. Estimated minimum central pressure is 1007
mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt.
Strong easterly wind shear is affecting the tropical depression,
causing the convection to be displaced to the west of the center.
Scattered moderate to isolated strong convection is noted from 10N
to 16N and between 28W and 33W. Seas near the center are up to 9
ft. A motion toward the northwest is forecast to begin by tonight
and continue through Tuesday. The depression is likely to become
a tropical storm tonight or Monday. By Tuesday, environmental
conditions are expected to become less conducive for development,
and the system is forecast to begin a slow weakening trend. Please
read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT2.shtml. For sea conditions
near this system, please read the Meteo-France High Seas Forecast
An Atlantic tropical wave has its axis along 30W, south of 19N,
and it is moving W near 10 kt. The convection in the vicinity of
the wave is mainly associated with T.D. Seventeen.
A monsoon trough extends across the Mauritania coast at 18N16W
through T.D. Seventeen, and to 06N42W. The ITCZ then continues
from 06N43W to 09N48W. Numerous moderate to strong convection is
occurring S of the monsoon trough along the coast of Senegal,
Gambia, Guinea-Bissau and Guinea in association with a tropical
wave that is nearing the African coast. Scattered moderate
convection is also found from 04N to 08N and between 37W and 41W.
The E Pacific monsoon trough protrudes into the SW Caribbean Sea
and it is causing scattered showers and thunderstorms within 80 nm
of the N coast of Panama and NW Colombia.
...GULF OF MEXICO...
A surface trough continues in the N Gulf, extending from the Big
Bend area of Florida to NE Texas, paralleling the southern coast
of Louisiana. A few showers and isolated thunderstorms are noted
near the trough axis. Another surface trough is located in the W
Bay of Campeche, resulting in scattered moderate convection from
21N to 24N and between 95W to the coasts of Veracruz and
Tamaulipas. The rest of the basin enjoys fairly tranquil weather
conditions. Moderate to locally fresh SE winds are observed in the
E Bay of Campeche, while gentle to moderate anticyclonic winds
are noted elsewhere. Seas of 1-3 ft are found in the Gulf.
For the forecast, weak high pressure will extend across the eastern
and central Gulf of Mexico through the early part of the week.
This pattern will support continued gentle to moderate winds and
mostly slight seas across the Gulf through Tue. Looking ahead, a
weak cold front may move into the northwest and north- central
Gulf by mid week.
A few showers are noted in the vicinity of the waters surrounding
Jamaica, but this activity appears to be weakening. Satellite-
derived wind data depict fresh to strong winds in the area, likely
due to strong downdrafts. The rest of the Caribbean Sea enjoys
fairly dry weather conditions. A recent scatterometer satellite
pass indicate fresh to locally strong trades off the coast of NW
Colombia and south of Hispaniola, especially off the Barahona
peninsula. Moderate to locally fresh trades are prevalent in the
rest of the Caribbean Sea. Seas of 4-7 ft are found in the central
and SW Caribbean, while 2-4 ft prevail elsewhere in the basin.
For the forecast, Tropical Storm Peter near 17.6N 56.5W 1007 mb at
1500 UTC moving WNW at 15 kt. Maximum sustained winds 40 kt gusts
50 kt. Peter is expected to continue WNW and reach near 19.3N
58.8W tonight, and near 20.2N 61.1W Mon afternoon, then veer more
NW through Tue, then turn northward toward Bermuda throughout the
rest of the week. As this occurs, trade winds over the south-
central Caribbean will diminish over the next several days. Look
for associated squalls and thunderstorms to begin affecting the
Leeward Islands and adjacent waters today.
Please read the Special Features section above for details on
Tropical Storm Peter E of the Leeward Islands and Tropical
Depression Seventeen WSW of the Cabo Verde Islands.
The surface trough over the N Gulf of Mexico spills into the
Atlantic waters off the NE coast of Florida, resulting in
scattered moderate convection from 27N to 32N and between 76W and
the coasts of Florida and Georgia. An upper level low near 23N64W
is interacting with a surface trough that extends from 26N59W to
19N60W, causing scattered moderate to isolated strong convection
from 22N to 26N and betwen 58W and 62W. A convergent wind flow is
resulting in a few showers and isolated thunderstorms along 66W
from 22N to 31N. The rest of the tropical Atlantic is dominated by
a strong subtropical ridge anchored near the Azores, maintaining
fairly tranquil weather conditions.
Recent scatterometer satellite data show strong to near-gale winds
to the N of the center of T.S. Peter from 18N to 21N and between
54W and 58W. Moderate to locally fresh winds prevail across the
rest of the tropical Atlantic. Seas are 3-6 ft W of 60W and 5-8 ft
E of 60W.
The Cumbre Vieja volcano in the island of La Palma in the Canary
Islands erupted around 1410 UTC. The ash plume is expected to
remain below 5000 ft and drift SE, causing a reduction in
visibility. Mariners should exercise caution.
For the forecast west of 60W, Tropical Storm Peter near 17.6N
56.5W 1007 mb at 1500 UTC moving WNW at 15 kt. Maximum sustained
winds 40 kt gusts 50 kt. Peter is expected to continue WNW with
little change in strength, reaching near 19.3N 58.8W tonight, near
20.2N 61.1W Mon afternoon, then veer more NW and reach near 22.5N
66.3W Tue evening, and 23.8N 67.0W Wed morning. Peter will then
move more northward in the general direction of Bermuda through
Sat. Elsewhere west of 70W, gentle to moderate winds and slight to
moderate seas will persist over open waters through the early
part of the week, with swell to 8 ft associated with the tropical
storm reaching the waters east of 72W by Wed.