[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200603
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Fri Aug 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 0000 UTC surface analysis and satellite imagery through
0550 UTC.

...SPECIAL FEATURES...

Tropical Storm Grace is centered near 20.8N 92.6W at 20/0600 UTC
or 270 nm E of Tuxpan, Mexico. It is moving W at 14 kt and the estimated
minimum central pressure is 994 mb. Maximum sustained wind speed
is 60 kt with gusts to 75 kt. Peak seas are currently 23 ft near
the center of Grace. Showers and thunderstorms have increased
during the past few hours over the center of Grace as the storm
reorganizes in the E Bay of Campeche after crossing the Yucatan
Peninsula. Scattered moderate isolated strong convection is from
19N to 22N and between 90W and 95W. A general westward
motion is expected early this morning, followed by a westward to
west-southwestward motion at a slower speed beginning later today.
On the forecast track, the center of Grace is forecast to move
across the southwestern Gulf of Mexico today, and then make landfall
along the coast of mainland Mexico this evening or tonight. Additional
strengthening is likely until Grace makes landfall, and the system
is expected to regain hurricane strength later this morning. After
landfall, Grace should weaken rapidly as it moves into the
mountains of central Mexico. Seas will increase as the system
moves across the Bay of Campeche, reaching up to 36 ft tonight.

Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT2.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT2.shtml for more
details.

Tropical Storm Henri is centered near 29.8N 72.3W at 20/0300 UTC
or 360 nm SSE of Cape Hatteras, North Carolina. It is moving W at
7 kt with an estimated minimum central pressure of 997 mb.
Maximum sustained wind speed is 55 kt with gusts to 65 kt. Peak
seas are currently 22 ft. Northerly wind shear continues to affect
the tropical storm, causing most of the convection to be located
in the southern semicircle. Numerous showers and thunderstorms are
noted from 26N to 31N and between 70W to 75W. A sharp turn
to the northwest and north is anticipated on Friday, followed by an
acceleration to the north and north-northeast on Saturday and
Sunday. On the forecast track, the center of Henri will remain well
offshore of the east coast of the United States over the next couple
of days, but it is forecast to be near or over southern New England
on Sunday and Monday. Little change in strength is expected during
the next 12 hours, but Henri is forecast to intensify into a
hurricane by Friday night with additional strengthening expected
this weekend. Swells generated by Henri should continue to affect
Bermuda during the next day or so. Swells are expected to increase
across much of the east coast of the U.S. and Atlantic Canada
later this week and this weekend. These swells could cause life-
threatening surf and rip current conditions.

Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT3.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT3.shtml for
more details.

...TROPICAL WAVES...

An Atlantic tropical wave has its axis along 30W, south of 21N,
and it is moving W at 10-15 kt. Scattered moderate convection is
noted mainly ahead of the wave axis from 09N to 15N and between
30W and 36W.

Another Atlantic tropical wave has its axis along 41W, south of
21N, and it is moving W at 10-15 kt. Scattered moderate
convection is on either side of the wave axis from 07N to 14N
and between 36W and 47W.

A third Atlantic tropical wave has its axis along 61W, near the
Lesser Antilles, south of 21N, and it is moving W at around 15
kt. A few showers are noted in the E Caribbean near and ahead of
the wave axis from 15N to 18N. Moisture associated with this wave
will continue to impact the eastern Caribbean and parts of the
Lesser Antilles today.

A Caribbean tropical wave has its axis along 73W, extending from
the E Bahamas to Colombia. It is moving W at 10-15 kt. The
southern portion of the wave and the Caribbean extension of the E
Pacific monsoon are likely enhancing the showers and thunderstorms
over N Colombia and W Venezuela, including Lake Maracaibo.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Mauritania near 20N16W
to 12N32W and to 10N51W. The ITCZ then extends from 10N52W to
07N58W. In addition to the convection associated with the
tropical waves, scattered moderate convection is observed from 11N
to 15N and between the coast of Africa to 21W.

...GULF OF MEXICO...

Refer to the Special Features section above for details on Tropical
Storm Grace.

Outside of the influence of Tropical Storm Grace, fairly tranquil
weather conditions are observed across the Gulf of Mexico. A
recent scatterometer satellite pass depict strong to near gale-
force winds associated with the circulation of Grace from 23N to
25N and roughly between 88W and 94W. Seas are 10-15 ft in this
area of high winds. Fresh to strong winds are also noted in
central and W Gulf, south of 26N, with seas of 6-10 ft. Moderate
to fresh winds are found in the NW Gulf with seas of 3-6 ft.
Lastly, a weak ridge in the NE Gulf is allowing gentle to
moderate breezes and seas of 1-3 ft in the area.

For the forecast, Tropical Storm Grace near 20.8N 91.8W 994 mb at 11 PM
EDT moving W at 14 kt. Maximum sustained winds 55 kt gusts 65 kt.
Grace will strengthen to a hurricane near 20.8N 93.7W Fri morning,
move to 20.7N 95.9W Fri evening, move inland and weaken to a
tropical storm near 20.1N 98.2W Sat morning, weaken to a remnant
low near 19.6N 100.5W Sat evening, and dissipate Sun morning. High
pressure will build in the wake of Grace and prevail through early
next week.

...CARIBBEAN SEA...

Scatterometer satellite data show fresh to strong trades affecting
the south-central Caribbean Sea, especially off the NW coast of
Colombia and the Gulf of Venezuela. Tropical Storm Grace continues
to move away from the Caribbean, but the scatterometer data also
depict fresh to strong E-SE winds in the Gulf of Honduras, and
these winds likely extend into the NW Caribbean, west of 84W.
Moderate to fresh trades prevail in the rest of the central and E
Caribbean. Seas in the NW Caribbean are 4-7 ft, while 3-6 ft are
prevalent in the central and E Caribbean and 2-4 ft in the SW
Caribbean. Scattered showers and thunderstorms are noted W of 79W
to the coast of Nicaragua and from 11N to 16N.

For the forecast, Grace will continue to move west of the area this evening,
with marine conditions gradually improving. Otherwise, moderate
to fresh trade winds will dominate elsewhere, except for locally
fresh to strong winds in the Gulf of Honduras tonight, and in the
central Caribbean early next week.

...ATLANTIC OCEAN...

Refer to the Special Features section above for details on Tropical
Storm Henri. Three tropical waves are moving westward between the
W coast of Africa and the Lesser Antilles. Please, see Tropical
Waves section for details.

Tropical Storm Henri is the only source of deep convection noted
across the tropical Atlantic as the basin remains under the
control of a broad 1024 mb subtropical ridge. The tight pressure
gradient previously present in the E Atlantic has relaxed,
allowing for moderate to fresh N-NE winds in the waters
surrounding the Canary Islands and off the NW coast of Africa.
Seas in this region are in the 6-9 ft range. Another area of
moderate to fresh easterlies is observed in recent scatterometer
data from 18N to 28N and between 35W to 62W. Seas in the area are
in the 5-8 ft range. Moderate to fresh trades are also noted north
of Puerto Rico and Hispaniola, with seas of 4-7 ft. Gentle to
moderate easterly winds prevail in the rest of the basin with seas
of 3-6 ft.

For the forecast, Tropical Storm Henri near 29.8N 72.3W 997 mb  at 11
PM EDT moving WNW at 7 kt. Maximum sustained winds 55 kt gusts 65
kt. Henri will move to 30.3N 73.2W Fri morning, move north of the
area to 31.8N 73.3W Fri evening, and strengthen to a hurricane
near 34.4N 72.2W Sat morning. Otherwise, moderate to fresh E to
SE winds will prevail E and across the Bahamas Fri through Mon,
except for fresh to locally strong winds at night north of
Hispaniola and the approaches to the Windward Passage.

$$
DELGADO
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