[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191746
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Aug 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
1700 UTC.

...SPECIAL FEATURES...

Tropical Storm Grace, currently inland over the Yucatan Peninsula,
is centered near 20.2N 88.8W at 19/1500 UTC or 75 nm W of Tulum,
Mexico moving W at 16 kt. Estimated minimum central pressure is
994 mb. Maximum sustained wind speed is 55 kt with gusts to 65
kt. Peak seas are currently 16 ft. Scattered moderate isolated
strong convection is from 17N to 23N between 84W and 91W,
including portions of the NW Caribbean, S Gulf of Mexico, and E
Bay of Campeche. A general westward to west-northwestward motion
is expected today, followed by a general westward to west-
southwestward motion at a slower speed over the weekend. On the
forecast track, Grace is expected to continue to move across the
Yucatan Peninsula today, and move over the southwest Gulf of
Mexico late tonight through Friday. Grace will likely make a
second landfall on the mainland coast of Mexico late Friday or
early Saturday. Additional weakening is possible while Grace moves
across land today. Re-intensification is likely after the center
reaches the Gulf of Mexico. Grace is forecast to be a hurricane
when it makes its second landfall on the mainland coast of Mexico
late Friday or early Saturday. Rapid weakening is expected after
Grace moves inland over central Mexico. 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 29.5N 70.5W at 19/1500 UTC
or 700 nm S of Nantucket, Massachusetts moving W at 8 kt.
Estimated minimum central pressure is 995 mb. Maximum sustained
wind speed is 60 kt with gusts to 75 kt. Peak seas are currently
25 ft. Numerous moderate isolated strong convection is from 27N to
31N between 68W and 73W. A turn toward the northwest is forecast
on Friday, followed by an acceleration toward the north and north-
northeast 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 southern New England on Sunday and Monday. Little change in
strength is expected today, but Henri is forecast to intensify
into a hurricane on Friday with additional strengthening predicted
to occur 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. 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...

A tropical wave is along 28W from 21N southward, moving W at
10-15 kt. Scattered moderate convection is from 06N to 13N
between 24W and 33W.

A tropical wave is along 38W from 22N southward, moving W at
10-15 kt. Scattered moderate convection is from 05N to 10N
between 38W and 43W.

A tropical wave is along 58W from 22N southward, moving W at
around 15 kt. Scattered moderate convection is impacting mainly
the Windward Islands, southern Leeward Islands, and E Caribbean,
within an area from 12N to 17N between 60W and 65W.

A tropical wave is along 71W from 22N southward, moving W at
around 10-15 kt. No convection is noted with the wave at this time.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from the coast of Mauritania near
17N16W to 13N28W to 09N46W. The ITCZ then extends from 09N46W to
09N56W. In addition to the convection associated with the
tropical waves, scattered moderate convection is from 08N to 18N
east of 20W.

...GULF OF MEXICO...

Refer to the Special Features section above for details on
Tropical Storm Grace, which is expected to enter the Bay of
Campeche later today.

Near gale to gale force E winds are affecting Gulf waters adjacent
to the northern Yucatan Peninsula with SE winds of similar force
in the Yucatan channel as Grace continues to move inland. Gale
force N winds are in the E Bay of Campeche ahead of Tropical Storm
Grace. Seas are 9-14 ft in these areas of high winds. Gentle to
moderate return flow is elsewhere as the basin continue to be
under the influence of surface ridging and a high pressure over
the Florida Panhandle. Seas are 4-6 ft in the northern and eastern
Gulf in SE to S swell. In the W Gulf, seas are 2-4 ft.

For the forecast, Grace will move to 20.6N 91.2W this evening,
strengthen to a hurricane near 20.6N 94.0W Fri morning, be near
20.4N 96.3W Fri evening, move inland and weaken to a tropical
storm near 20.0N 98.7W Sat morning. Conditions associated with
Grace will affect the Yucatan channel and region N of the Yucatan
Peninsula today and the Bay of Campeche tonight through Sat.

...CARIBBEAN SEA...

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

Strong to gale force E to SE winds persist in the W Caribbean and
Yuctan Channel as Tropical Storm Grace continues inland over the
Yucatan Peninsula. Seas are 10-16 ft in the far NW Caribbean, and
6-10 ft in the remainder of the W Caribbean. In the E and Central
Caribbean, moderate to fresh trades prevail with 4-7 ft seas,
except in the SW Caribbean where seas are 2-4 ft. Scattered
moderate convection is in the SW Caribbean from 10N to 15N west of
80W.

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

...ATLANTIC OCEAN...

Please refer to the sections above for details on Tropical Storm
Henri and on the tropical waves moving across the basin.

The tropical Atlantic is dominated by a 1024 mb subtropical
High north of the discussion area, which has gradually been
Advancing south behind Tropical Storm Henri. Gentle to moderate
NE winds, becoming locally fresh east of the Lesser Antilles,
Keep seas around 4-7 ft in the waters east of 60W. Winds veer to
SE north of 23N between 60W and 70W as the flow begins to enter
Tropical Storm Henri's circulation. Farther west, at 1500 UTC the
ASCAT data depicated a 1021 mb high near 30N80W, producig gentle
Flow across waters west of 75W. Seas are 2-4 ft near and W of the
Bahamas. East of the Bahamas, seas build to 10-15 ft near Henri.

For the forecast, Henri will move to 29.7N 71.9W this evening,
30.4N 72.9W Fri morning, strengthen to a hurricane near 31.9N
72.9W Fri evening, 34.4N 72.0W 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 N
of Hispaniola and the approaches to the Windward Passage.

$$
Mahoney
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