[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170734
TWDAT

Tropical Weather Discussion...UPDATED
NWS National Hurricane Center Miami FL
0605 UTC Tue Aug 17 2021

Updated to include information from the Intermediate Advisories on
FRED, GRACE, and HENRI.

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
0500 UTC.

...SPECIAL FEATURES...

FRED: Tropical Storm Fred is centered inland near 31.7N 85.2W at
17/0600 UTC or 25 nm NNE of Dothan, Alabama, moving N at 12 kt.
Estimated minimum central pressure is 1004 mb. Maximum sustained
wind speed is 35 kt with gusts to 45 kt. Convection is no longer
impacting the Gulf of Mexico. Seas in the NE Gulf are currently
8-10 ft and will diminish to 3-5 ft on Tuesday. 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 Wednesday. Weakening
is expected to continue, and Fred should become a tropical
depression later this morning. 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.

GRACE: At 17/0600 UTC, reconnaissance aircraft found that Grace
has re- strengthened into a tropical storm. Grace is centered near
18.1N 74.5W at 17/0600 UTC or 200 nm E 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.
Numerous moderate isolated strong convection is noted from 15N to
19N between 72W and 76W. Peak seas are currently at 9 ft near the
center of Grace, and are expected to build to 13 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 continue to move near or over the Tiburon Peninsula of Haiti
during the next couple of hours, and then move between
southeastern Cuba and Jamaica this afternoon. Grace is forecast
to move near the Cayman Islands tonight and then approach the
Yucatan Peninsula of Mexico late Wednesday or early Thursday.
Strengthening is forecast during the next few days, and Grace is
forecast to become a tropical storm on Tuesday. Additional strengthening
is forecast during the next few days, and Grace could be near
hurricane strength when it approaches the Yucatan coast of Mexico
in a couple of days. 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.

HENRI: Tropical Storm Henri (pronounced ahn-REE) is centered near
30.6N 63.5W at 17/0600 UTC, or 130 nm SSE of Bermuda, moving SW
at 4 kt. Estimated minimum central pressure is 1008 mb. Maximum
sustained wind speed is 40 kt with gusts to 50 kt. Scattered
moderate convection is from 28N to 32N between 61W and 64W. 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 Thursday. 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.

...TROPICAL WAVES...

An Atlantic tropical wave extends its axis along 37W from 21N
southward, moving westward at 10-15 kt. Scattered moderate
convection is from 04N-09N between 27W-36W.

An Atlantic tropical wave extends its axis along 52W from 20N
southward, moving westward at 10-15 kt. Scattered showers
are within 120 nm east and west of the wave axis.

A western Caribbean tropical wave extends its axis along 85W from
21N southward, moving westward at 10-15 kt. No convection is noted
at this time.

...MONSOON TROUGH/ITCZ...

The monsoon trough 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
near the monsoon trough from 09N to 15N E of 22W. This convection
is being enhanced by a tropical wave that recently moved off the
coast of Africa, and this tropical wave will be analyzed beginning
with the 0600 UTC surface analysis.

...GULF OF MEXICO...

With Tropical Storm Fred moving inland, conditions continue to
improve across the NE Gulf. The latest scatterometer depicts
moderate to fresh S to SW winds in this area with 6-10 ft seas.
Elsewhere in the basin, including the Straits of Florida, light to
gentle trades prevail with 2-4 ft seas.

For the forecast, Fresh to strong southwest winds over the far
northeast part of the NE Gulf will diminish early Tue. Tropical
Storm Grace will be near 18.6N 75.7W Tue morning with maximum
sustained winds 35 kt gusts 45 kt, move to near 19.1N 78.8W Tue
evening, to near 19.7N 82.0W Wed morning with maximum sustained
winds 45 kt gusts 55 kt, to near 20.3N 85.1W Wed evening with
maximum sustained winds 50 kt gusts 60 kt and inland the northern
Yucatan Peninsula near 21.0N 88.2W early Thu. Grace will
strengthen as it reaches near 21.6N 91.3W Thu evening, then
strengthen to a hurricane near 22.2N 95.9W Fri evening with
maximum sustained winds 65 kt gusts 80 kt and move inland near
22.5N 100.0W by late Sat. 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 section above for details on Tropical Storm Grace.

Outside of the wind field of Grace, the latest scatterometer data
depicts 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, Grace will be near 18.6N 75.7W Tue morning with
maximum sustained winds 35 kt gusts 45 kt, move to near 19.1N
78.8W Tue evening, to near 19.7N 82.0W Wed morning with maximum
sustained winds 45 kt gusts 55 kt, to near 20.3N 85.1W Wed evening
with maximum sustained winds 50 kt gusts 60 kt and inland the
northern Yucatan Peninsula near 21.0N 88.2W early Thu. 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 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, Grace will move between Jamaica and
southeastern Cuba Tue morning and continue in west-northwest
motion continuing to strengthen as it approaches the northern
Yucatan Peninsula late Wed into 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 30.7N 63.3W 1008 mb at 11 PM
EDT moving SW at 4 kt. Maximum sustained winds 40 kt gusts 50 kt.
Henri will strengthen some as it moves to near 30.5N 63.8W Tue
morning, to near 30.4N 64.8W Tue evening with maximum sustained
winds 50 kt gusts to 60 kt, and maintain intensity as it moves to
near 30.3N 66.2W early Wed, to near 30.3N 67.8W Wed evening, to
near 30.5N 69.3W early Thu, to near 31.3N 70.1W Thu evening and to
just north of the area near 32.8N 69.7W Fri evening. Otherwise,
high pressure will persist across the area through the period.

$$
Mahoney
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