Tropical Weather Discussion – Friday 9/18

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Fri Sep 18 2020

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 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1710 UTC.

…SPECIAL FEATURES

Category 4 Hurricane Teddy is centered near 22.1N 56.1W at
18/1500 UTC, or 456 nm ENE of the northern Leeward Islands
and 769 nm SE of Bermuda, moving NW at 10 kt. Estimated
minimum central pressure is 947 mb. Maximum sustained wind
speed is 115 kt with gusts to 140 kt. Peak seas are currently
45 ft with 12 ft seas extending 420 nm in the N semicircle and
300 nm in the S semicircle. Scattered moderate to strong
convection is located 130 nm in the NE quadrant and scattered
moderate convection is located 200 nm in the NW quadrant and
the S semicircle. Teddy is expected to continue moving NW for
the next couple of days, followed by a turn toward the north by
early next week. On the forecast track, Teddy will be
approaching Bermuda late Sunday or Monday. Some fluctuations in
strength are expected during the next day or so, and a weakening
trend is forecast to begin late this weekend. Large swells that
are being generated by Teddy are reaching the Lesser Antilles
and the northeastern coast of South America. These swells spread
westward to the Greater Antilles, the Bahamas, Bermuda, and the
eastern coast of the United States of America by the weekend. It
is likely for the swells to cause life- threatening surf and rip
current conditions. Please read the latest NHC Public Advisory
at: https://www.nhc.noaa.gov/text/MIATCPAT5.shtml, and the
Forecast/ Advisory at
https://www.nhc.noaa.gov/text/MIATCMAT5.shtml, for more details.

Newly formed Tropical Storm Wilfred is centered near 11.9N 32.4W
at 18/1500 UTC, or 547 nm WSW of the Cabo Verde Islands, moving
WNW at 15 kt. Estimated minimum central pressure is 1008 mb.
Maximum sustained wind speed is 35 kt with gusts to 45 kt. Peak
seas are currently less than 8 ft. Scattered moderate to
isolated strong convection is within 200 nm of the W semicircle.
Wilfred will continue moving WNW for the next few days. Some
slight strengthening is possible today, and weakening should
start this weekend and continue into next week. Please read the
latest NHC Public Advisory at:
https://www.nhc.noaa.gov/text/MIATCPAT3.shtml, and the Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT3.shtml for
more details.

Tropical Depression Twenty-Two is centered near 23.8N 93.9W at
18/1500 UTC, or 239 nm ENE of Tampico, Mexico and 222 nm SE of
the mouth of the Rio Grande, moving NNE at 6 kt. Estimated
minimum central pressure is 1005 mb. Maximum sustained wind
speed is 30 kt with gusts to 40 kt. Peak seas are currently
less than 8 ft. Scattered moderate to strong convection is
within 200 nm in the NE quadrant and scattered thunderstorms
are seen 170 nm in the S semicircle. The depression will
continue to move NNE through early Saturday. A slow westward
motion is forecast to begin late Saturday or Saturday night, and
this motion will likely continue into early next week.
Strengthening is forecast during the next few days, and the
depression is expected to become a tropical storm later today.
The system could be near or at hurricane strength by Sunday.
Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT2.shtml, and the
Forecast/Advisory at
https://www.nhc.noaa.gov/text/MIATCMAT2.shtml for more details.

Newly formed Subtropical Storm Alpha is centered near the
coast of Portugal near 39.9N 9.3W at 18/1630 UTC, or about
65 nm N of Lisbon, Portugal, moving NE at 15 kt. Estimated
minimum central pressure is 999 mb. Maximum sustained wind
speed is 40 kt with gusts to 50 kt. Scattered showers and
isolated thunderstorms are within 200 nm of the NE quadrant
moving across Portugal and portions of NW Spain. Subtropical
Storm Alpha will continue moving NE during the next day or
so before dissipation. Alpha should move across the coast
of west-central Portugal during the next couple of days.
Little change in strength is expected before landfall,
with rapid weakening over land through the weekend. Please
read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT4.shtml, and the
Forecast/Advisory at
https://www.nhc.noaa.gov/text/MIATCMAT4.shtml for more details.

…MONSOON TROUGH/ITCZ…

The monsoon trough extends off the Mauritania coast near 20N16W
to 17N21W. No significant convective is noted at this time with
this feature. The monsoon trough and the ITCZ have been
disrupted by the activity of the current tropical cyclones.

GULF OF MEXICO…

Please see the Special Features section above for details on
Tropical Depression Twenty-Two located in the western Gulf.

A slow moving cold front continues to sink southward across
the Gulf, extending from the Tampa Bay area near 28N83W to
26N90W. The tail-end of the front stalls from 26N90W to 26N94W.
A pre-frontal trough is noted south of the front from 27N83W
to 25N88W. Scattered showers with isolated thunderstorms are
seen along the pre-frontal trough. Convection is currently
seen across the western portion of the front interacting with
TD Twenty-Two from 22N-28N between 88W-94W. Light to gentle
winds are in the eastern Gulf with moderate to fresh winds
in the western Gulf. Seas 2 to 4 ft can be seen across the
basin with upwards of 7 ft near T.D. Twenty-Two.

Tropical Depression Twenty-Two will strengthen to a tropical
storm near 24.8N 93.6W this evening, move to 25.9N 93.4W Sat
morning, 26.3N 93.8W Sat evening, 26.5N 94.6W Sun morning,
strengthen to a hurricane near 26.6N 95.6W Sun evening, and
26.9N 96.2W Mon morning. Twenty-Two will weaken to a tropical
storm near 27.5N 96.5W by early Tue. A cold front will move
through the northeast Gulf through the weekend, bringing fresh
NE winds into early next week.

CARIBBEAN SEA…

A 1010 mb low is located in the east-central Caribbean near
15N65W with a trough extending along the low from 16N60W to
17N71W. Scattered thunderstorms are seen along this feature
from 14N-16N between 62W-67W.

The monsoon trough extends across the SW Caribbean from 11N76W
to the SW Nicaraguan coast near 11N84W. A 1011 mb low is along
the monsoon trough near 10N78W. Scattered moderate convection
is noted along the monsoon trough from 09N-12N between 75W-83W.
Light to gentle trades are noted across the Caribbean with
moderate trades north of the monsoon trough and moderate trades
in the eastern Gulf of Honduras. Seas range 3-5 ft.

Major Hurricane Teddy will move northward away from tropical
Atlantic waters for the rest of the week. Long-period
northeasterly swell generated by Teddy are expected to impact
most of the central Atlantic through the next few days. T.S.
Wilfred has developed in the eastern Atlantic. This system may
impact portions of Atlantic waters well east of the Lesser
Antilles by early next week.

ATLANTIC OCEAN…

Please see Special Features section above for details on
Hurricane Teddy, T.S. Wilfred, and Subtropical Storm Alpha.

A cold front extends off the NE Florida coast from 31N80W to
south of St. Augustine, FL near 30N81W. Isolated thunderstorms
are noted ahead of the front in the western Atlantic from 28N-
31N between 76W-79W. Moderate to fresh WSW winds are noted
across this area of the Atlantic with seas up to 7 ft.

The remnants of Vicky are centered near 20N41W with a minimum
central pressure of 1012 mb. Showers are seen near the center of
this low. A trough is noted in the central Atlantic from 30N32W
to 24N34W, about 600 nm S of the Azores. No significant
convection is associated with this feature. Outside of the
tropical systems, winds are gentle to moderate. Fresh to strong
northerly winds are noted off the Western Sahara/Mauritania
coast.

Category 4 Hurricane Teddy will move to 23.3N 57.2W this
evening, 25.2N 58.9W Sat morning, 27.1N 60.7W Sat evening, 28.7N
62.2W Sun morning, 30.7N 62.7W Sun evening, and 33.7N 62.2W Mon
morning. Teddy will change little in intensity as it moves near
41.4N 62.5W by early Tue. Swell generated by Teddy will impact
the Bahamas this weekend. A strong cold front will move off the
southeastern U.S. coast Fri night, then gradually weaken and
become stationary from near Bermuda into southern Florida early
next week. Near gale force northeast winds are expected north of
the Bahamas this weekend into early next week, along with
building seas.

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