[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091804
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Thu Sep 9 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
1630 UTC.

...SPECIAL FEATURES...

Hurricane Larry is centered near 32.0N 61.6W at 09/1500 UTC or
170 nm E of Bermuda and moving NNW at 14 kt. Estimated minimum
central pressure is 966 mb. Maximum sustained wind speed is 80
kt with gusts to 100 kt. Seas are peaking near 37 ft near and just
N of the center. Numerous moderate to strong convection is noted
in a semi circle up to 80 nm N of the center. Scattered moderate
convection is seen in a semi circle up to 100 nm S of the center.
On the forecast track, the center of Larry will pass east of
Bermuda later this afternoon, and move near or over southeastern
Newfoundland Fri night or Sat morning. Gradual weakening is
forecast to start on Fri night, but Larry is expected to remain a
hurricane through Sat before undergoing extratropical transition.
Please read the latest High Seas Forecast issued by the National
Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest NHC
Forecast/Advisory and Public Advisory at www.hurricanes.gov for
more details.

Tropical Depression Mindy has exited into the Atlantic Ocean and
is centered near 31.5N 80.7W at 09/1500 UTC or 40 nm SSE of
Savannah, Georgia. It is moving ENE at 18 kt with an estimated
minimum central pressure of 1005 mb. Maximum sustained wind speed
is 30 kt with gusts to 40 kt. Radars indicate scattered moderate
convection NNE of the center, along the coast of S and N
Carolinas. Seas are from 7 to 9 ft off the Georgia and NE Florida
coasts. On the forecast track, Mindy is expected to continue
moving ENE across the Atlantic through Fri evening. Mindy is not
expected to restrengthen due to unfavorable upper level winds
and might become post tropical on Fri night. Please read the
latest Offshore Zones Forecast issued by the National Hurricane
Center at website https://www.nhc.noaa.gov/text/MIAOFFNT4.shtml
and the latest NHC Forecast/Advisory and Public Advisory at
www.hurricanes.gov for more details.

...TROPICAL WAVES...

An Atlantic tropical wave is near 30W from 21N southward and
moving W near 15 kt. A surface trough is noted in association
with this wave. Scattered moderate convection is found from 04N to
07N between 25W and 37W.

Another Atlantic tropical wave is along 46W from 20N southward and
moving W at 10 to 15 kt. A surface circulation and related trough,
are behind this wave axis near 12N41W. These features might
become closer to each other later on. Scattered moderate
convection is seen from 06N to 16N between 39W and 46W.

A Caribbean tropical wave is near 68W from 15N southward across
N Venezuela and SE Colombia, and moving W near 15 kt. The wave is
mainly monitored through the 700 mb trough diagnostics and the
700 mb rawindsonde observations. Scattered showers and isolated
thunderstorms are occurring over S Venezuela.

...MONSOON TROUGH/ITCZ...

A monsoon trough passes through the Gambia coast near 14N17W to
13N31W. No ITCZ is present based on the latest analysis.
Scattered moderate convection is found S of the trough axis from
03N to 06N between 18W and 23W.

...GULF OF MEXICO...

A surface trough runs northeastward from 22N95W to 26N94W across
the W Gulf. Aided by a mid to upper-level trough in the vicinity,
scattered showers and thunderstorms are flaring up over much of
the Gulf, except waters off the N Mexico coast. Moderate to
locally fresh winds and seas at 3 to 5 ft are evident at the NE
Gulf near the Florida Big Bend coast. Light to gentle winds and
seas at 2 to 3 ft prevail across the rest of the Gulf.

For the forecast, Tropical Depression Mindy is over the Atlantic
waters E of the coast of Georgia. The northern portion of a
tropical wave over northeastern Honduras and the western Caribbean
Sea is forecast to emerge over the southern Bay of Campeche on
Saturday. Environmental conditions are expected to be conducive to
support some gradual development of the system before it moves
over mainland Mexico early next week.

...CARIBBEAN SEA...

Convergent trade winds are coupling with divergent flow aloft to
trigger scattered showers and thunderstorms over the NW basin,
including the coast of the Yucatan Peninsula and Honduras. The
E end of the E Pacific monsoon trough is producing similar
conditions at the SW basin, including the coast of Nicaragua,
Costa Rica and Panama.

Due to weaker pressure gradient between the mid-Atlantic ridge and
the lower pressure over Colombia, mainly gentle to moderate trades
and seas at 3 to 5 ft are present across much of the basin.
Locally fresh winds and seas up to 6 ft are possible in stronger
thunderstorms.

For the forecast, swells generated by Hurricane Larry will
gradually subside across Atlantic waters of the Leeward Islands,
Puerto Rico, and Hispaniola today. As Larry moves farther north,
the Atlantic ridge will build westward N of the Caribbean Sea
bringing an increase in the trade wind flow tonight into the
weekend. Locally strong winds are possible offshore Colombia,
mainly during the nights.

...ATLANTIC OCEAN...

Please see the Special Features section above for details on
Major Hurricane Larry near Bermuda and Tropical Depression Mindy
just off the coast of Georgia.

Convergent moderate SW to W winds SW and S of Tropical Depression
Mindy are causing scattered showers and isolated thunderstorms
across N and central Florida, and over NW and central Bahamas. A
pronounced upper-level trough S of the Azores near 30N29W is
producing scattered moderate convection N of 25N between 20W and
30W. Refer to the Tropical Waves and Monsoon Trough/ITCZ sections
for additional convection across the Atlantic Basin.

Larger swells traveling farther away from Larry are generating
seas of 5 to 8 ft N of 23N between 69W and the Florida-Georgia
coast, including the Bahamas. Similar seas are also found from 21N
to 25N between 56W and 69W, and N of 24N between 48W and 53W. For
the remainder of the basin, seas range from 4 to 6 ft. Outside
the influence of Larry, light to gentle winds are present from the
N coast of the Greater Antilles to beyond 31N between 67W and
77W. Gentle to moderate NE trades are dominating N of 10N between
the African coast and 53W/Windward Islands. Light to gentle S to
SW winds prevail S of 10N.

For the forecast, Tropical Depression Mindy near 31.5N 80.7W 1005
mb at 11 AM EDT moving ENE at 18 kt. Maximum sustained winds 30
kt gusts 40 kt. Mindy will move to 32.5N 77.5W this evening, 33.6N
73.4W Fri morning, become post-tropical and move to 34.3N 70.3W
Fri evening, and dissipate Sat morning. Mindy is causing a brief
period of fresh to strong SW to W winds N of 29N and W of 75W
today. Large swells, currently E of 70W, generated by Hurricane
Larry to the east, will continue to propagate to around 80W by
tonight, with seas of over 8 ft expected N of the Bahamas. Seas
will then subside into the weekend.

$$

Chan
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