[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171047
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Tue Aug 17 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 0600 UTC surface analysis and satellite imagery through
1030 UTC.

...SPECIAL FEATURES...

Recently upgraded Tropical Storm Grace is centered near 18.2N
75.4W at 17/0900 UTC or about 145 nm east of Montego Bay, Jamaica
moving W at 12 kt. Estimated minimum central pressure is 1005 mb.
Maximum sustained wind speed is 35 kt with gusts to 45 kt.
Satellite imagery shows numerous moderate to isolated strong from
15N to 19N between 72W and 76W, including the southwest part of
Haiti and some sections of the southern coast of the Dominican
Republic Peak seas are currently at 9 ft near the center of Grace,
and are expected to build to near at 12 ft this morning. A
general westward to west-northwestward motion is expected for the
next several days. On the forecast track, the center of Grace will
move near the northern coast of Jamaica this afternoon. Grace is
forecast to move near the Cayman Islands tonight, and then
approach the Yucatan peninsula of Mexico late Wed or early Thu.
Gradual strengthening is forecast during the next couple of days,
and Grace could be near hurricane strength when it approaches the
Yucatan coast of Mexico late Wed and early Thu. 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 (pronounced ahn-REE) is centered near 30.6N
63.7W at 17/0900 UTC, or 115 nm SSE of Bermuda, moving WSW at 4
kt. Estimated minimum central pressure is 1004 mb. Maximum
sustained wind speed has increased to 45 kt with gusts to 55 kt.
Satellite imagery shows increasing numerous moderate convection
within 90 nm E and 30 nm W semicircles of center. Seas are
currently 8-10 ft near Henri, and are expected to build to 16 ft
by tonight. A turn toward the west is is forecast by tonight, and
a slightly faster westward motion should continue through early
Thu. On the forecast track, the center of Henri should pass well
to the south of Bermuda late today or tonight. Some additional
strengthening is possible during the next day or so. 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.

Recently downgraded Tropical Storm Fred is centered inland near
32.3N 85.0W at 17/0900 UTC or about 15 miles south-southwest of
Columbus, Georgia moving NNE at 12 kt. Estimated minimum central
pressure is 1004 mb. Maximum sustained wind speed is 30 kt with
gusts to 40 kt. Convection is no longer impacting the Gulf of
Mexico. Seas over the far NE Gulf have subsided to 6-8 ft and
will continue to do so today. On the forecast track, the center of
Fred will move across western and northern Georgia today, across
the southern Appalachian Mountains tonight, and into the central
Appalachians by early Wed. Additional weakening is forecast during
the next couple of days and Fred is expected to degenerate into a
remnant low by tonight and merge with a frontal system on Wed.
Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT1.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT1.shtml for more
details.

...TROPICAL WAVES...

A far eastern Atlantic tropical wave was introduced along 20N
from 08N to 25N at 06Z. It is moving westward at 10-15 kt.
Increasing numerous moderate to strong convection is east of the
wave to inland the coast of Africa from 09N to 15N. Scattered
moderate to isolated strong convection is within 120 nm west of
the wave from 07N to 15N.

An eastern Atlantic tropical wave has its axis along 39W from 03N
to 23N. It is moving westward near 15 kt. Only isolated showers
and thunderstorms are within 120 nm east of the wave from 03N to
10N.

A central Atlantic tropical wave has its axis along 54W from 20N
southward to inland Suriname. It is moving westward at 10-15 kt.
Scattered showers and thunderstorms are within 180 nm east of the
wave from 09N to 10N and west of the wave from 09N to 10N to
inland the coast Venezuela.

A western Caribbean tropical wave has its axis along 86W from 22N
southward to northern Costa Rica, moving westward at 10-15 kt. No
convection is noted at this time.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from the border of Western Sahara
near 22N17W to 15N26W to 08N44W. The ITCZ then continues from
08N44W to 08N50W. Scattered moderate to isolated strong convection
is seen from 04N to 09N between 28W-31W.

...GULF OF MEXICO...

With Tropical Depression Fred continuing to move farther inland,
this will allow for the gradient to relax further over the NE
Gulf. SW winds there have diminished to moderate to fresh speeds
and will continue to diminish during the day. Elsewhere across
the Gulf, including the Straits of Florida, light to gentle trades
prevail with 3-4 ft seas.

For the forecast recently upgraded Tropical Storm Grace near
18.2N 75.4W 1005 mb at 5 AM EDT is moving W at 14 kt. Maximum
sustained winds 35 kt gusts 45 kt. Grace will move to near 18.6N
77.6W this afternoon, to near 19.1N 80.7W late tonight, to near
19.7N 83.9W Wed afternoon with maximum sustained winds 50 kt gusts
60 kt, to near 20.4N 87.0W late Wed night with maximum sustained
winds 60 kt gusts 75 kt, to inland the northern Yucatan Peninsula
near 21.0N 90.0W Thu afternoon, to near 21.4n 92.7W late Thu
night, to near 22.0N 97.2W late Fri night with maximum sustained
winds 60 kt gusts 75 kt and to inland 22.3N 101.4W late Sat night.
Fresh to strong east winds on the northern periphery of Grace are
expected over the southeastern Gulf waters from Tue night through
Wed night, shifting westward across the central Gulf through Sat
night.

...CARIBBEAN SEA...

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

Outside of the wind field of Grace, overnight ASCAT data passes
showed moderate to fresh winds in the eastern and central
Caribbean and light to gentle trades in the western Caribbean,
pulsing to moderate in the Gulf of Honduras. Seas are 5-7 ft in
the east- central Caribbean, 4-6 ft near the Windward Islands, 3-5
ft near the Leeward Islands and in the west-central Caribbean,
and 3 ft or less in the western Caribbean.

For the forecast, recently upgraded Tropical Storm Grace near
18.2N 75.4W 1005 mb at 5 AM EDT is moving W at 14 kt. Maximum
sustained winds 35 kt gusts 45 kt. Grace will move to near 18.6N
77.6W this afternoon, to near 19.1N 80.7W late tonight, to near
19.7N 83.9W Wed afternoon with maximum sustained winds 50 kt gusts
60 kt, to near 20.4N 87.0W late Wed night with maximum sustained
winds 60 kt gusts 75 kt and inland the northern Yucatan Peninsula
near 21.0N 90.0W Thu afternoon. Elsewhere, fresh to strong
northeast to east trades will be over the central Caribbean will
Tue through Wed night.

...ATLANTIC OCEAN...

Please refer to the Special Features section above for details on
Tropical Storm Henri.

The tight pressure gradient in the eastern Atlantic near the
Canary Islands supports near gale force NE winds, which were
detected by the latest scatterometer pass. 6-9 ft seas are noted
in the areas of strongest wind. Elsewhere, surface ridging and a
weak pressure gradient prevails. Fresh trades are noted from the
Turks and Caicos south to the coast of Hispaniola, and in the
Windward Passage with seas of 6-9 ft. Gentle to moderate E to SE
winds are over the western Atlantic, including the Bahamas and
areas north of the Turks and Caicos. Light winds are north of 22N
between 40W and 67W. Gentle to moderate trades are south of 24N in
the remainder of the basin, except moderate to fresh NE winds
north of 25N east of 20W. Seas are generally 3-6 ft across the
basin, with the highest seas near Puerto Rico and the Windward
Islands.

For the forecast west of 65W, Tropical Storm Grace will move
near the the northern coast of Jamaica this afternoon. Grace is
forecast to move near the Cayman Islands tonight, and then
approach the Yucatan peninsula of Mexico late Wed or early
Thu. Fresh to strong east to southeast winds north of Grace are
over the waters from the southeastern Bahamas to the Dominican
Republic. These winds will shift westward to the Straits of
Florida through early Wed afternoon. Tropical Storm Henri near
30.6N 63.7W 1004 mb at 5 AM EDT moving WSW at 4 kt. Maximum
sustained winds 45 kt gusts 55 kt. Henri will move to near 30.4N
64.4W this afternoon, to near 30.3N 65.7W late tonight with
maximum sustained winds 55 kt gusts 65 kt and maintain intensity
as it moves to near 30.2N 67.1W Wed afternoon, to near 30.3N 68.6W
late Wed night, to near 30.8N 69.8W Thu afternoon, near 31.6N
70.6W late Thu night and to north of the area near 34.0N 69.1W
late Fri night. Otherwise, high pressure will persist across the
area through the period.

$$
Aguirre
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