[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 100605
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Fri Sep 10 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
0605 UTC.

...SPECIAL FEATURES...

Hurricane Larry is centered near 36.5N 62.2W at 10/0600 UTC or 735
nm SW of Cape Race, Newfoundland. Larry is moving N at 22 kt.
Estimated minimum central pressure is 966 mb. Maximum sustained
wind speed is 80 kt with gusts to 100 kt. Numerous moderate to
strong convection is noted in the northern semicircle up to 200
nm and scattered moderate convection is seen in the southern
semicircle up to 115 nm. On the forecast track, the center of
Larry will continue to move away from Bermuda tonight, and move
near or over southeastern Newfoundland Friday night or early
Saturday morning. Gradual weakening is forecast to begin on
Friday, but Larry is expected to remain a hurricane until it
passes Newfoundland. Larry should become an extratropical cyclone
on Saturday, and is now forecast to be absorbed by a larger
extratropical low near Greenland by the end of the weekend. 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.

A robust tropical wave is producing scattered moderate to strong
convection over W Africa. The tropical wave is expected to move
into the far eastern Atlantic later today or tonight.
Environmental conditions are forecast to be conducive for
development thereafter, and a tropical depression is likely to
form by early next week as the system moves west-northwestward
over the far eastern Atlantic near the Cabo Verde Islands. The
disturbance has a medium chance of development over the next 48
hours and a high chance of development over the next 5 days.
Please see the latest Tropical Weather Outlook from the National
Hurricane Center.

...TROPICAL WAVES...

An Atlantic tropical wave has its axis along 33W, south of 21N,
and it is moving W near 15 kt. No deep convection is noted with
this tropical wave.

Another Atlantic tropical wave has its axis along 47W, south of
21N, and it is moving W at 10-15 kt. No deep convection is noted
with this tropical wave.

A Caribbean tropical wave has its axis along 71W, extending from
Hispaniola to W Venezuela and SE Colombia, and it is moving W
near 15 kt. The wave is mainly monitored through the 700 mb trough
diagnostics and the 700 mb rawindsonde observations. No deep
convection is noted with this tropical wave. However, it is
enhancing the development of showers and thunderstorms over SE
Colombia.

A Caribbean tropical wave has been introduced along 87W, extending
from the Gulf of Honduras, across Honduras and E Nicaragua, and
into the E Pacific. Scattered moderate convection is noted east of
the wave axis to 80W and from 17N to 22N. This system is forecast
to move into the Bay of Campeche and merge with a pre-existing
surface trough located over the southwestern Gulf of Mexico by
this weekend. Environmental conditions are expected to be
conducive to support some gradual development, and a tropical
depression could form by early next week before the system moves
inland over mainland Mexico. For more details, please read the
latest Tropical Weather Outlook from the National Hurricane
Center.

...MONSOON TROUGH/ITCZ...

A monsoon trough passes through the Guinea-Bissau coast near
11N16W to 08N28W and to 12N40W. No ITCZ segment is analyzed based
on recent scatterometer satellite data. Scattered moderate
convection is noted south of monsoon trough from the coast of
Africa to 29W.

...GULF OF MEXICO...

A cold front extends from the Florida panhandle near 31N86W to
south of Louisiana near 29N93W, and then continues as a stationary
front to the coast of SE Texas near 29N95W. A surface trough is
located over the W Gulf of Mexico from 19N92W to 28N95W. The
combination of these features and a mid to upper-level trough in
the vicinity is causing a large area of scattered showers and
thunderstorms, especially from 22N to 28N and between 87W and 94W.
A recent scatterometer satellite pass show gentle to moderate
anticyclonic winds dominating the Gulf. Seas of 1-3 ft are found
across the basin.

For the forecast, the northern portion of a tropical wave is
producing disorganized showers and thunderstorms across the
western Caribbean Sea. This system is forecast to move into the
Bay of Campeche and merge with a pre-existing surface trough
located over the southwestern Gulf of Mexico by this weekend.
Environmental conditions are expected to be conducive to support
some gradual development, and a tropical depression could form by
early next week before the system moves inland over mainland
Mexico. This system has a low chance of development in 48 hours
and medium chance in the next 5 days. Regardless of development,
this system could bring an increase in winds and seas across the
Gulf waters during the upcoming weekend.

...CARIBBEAN SEA...

Please see the Tropical Waves section for details on the tropical
waves moving across the area.

Most of the Caribbean Sea is dominated by dry weather conditions
that are inhibiting the development of showers and thunderstorms.
A recent scatterometer satellite pass depict strong to locally near
gale-force trades in the south-central Caribbean, especially
within 150 nm of the NW coast of Colombia. Moderate to fresh
trades are found in the north-central Caribbean, E Caribbean and
NW Caribbean, while gentle to moderate trades are noted in the SW
Caribbean. Seas of 6-9 ft are prevalent in the south-central
Caribbean and 3-6 ft elsewhere in the basin.

For the forecast, as Larry continues to move farther north, the
Atlantic ridge will build westward N of the Caribbean Sea. This
will bring an increase in the trade wind flow tonight into the
weekend. Fresh to strong winds are possible offshore Colombia and
in the Gulf of Venezuela, mainly during the nights. Fresh to
locally strong winds are also likely in the late evening in the
Gulf of Honduras Friday and Saturday.

...ATLANTIC OCEAN...

Please see the Special Features section above for details on Hurricane
Larry over the NW Atlantic.

The 1024 mb subtropical ridge is beginning to re-assert dominance
over the tropical Atlantic as Hurricane Larry continues to move
away. Recent scatterometer satellite data and satellite imagery
indicate that a weak 1014 mb low pressure is located near 12N44W.
It is producing disorganized showers and thunderstorms, especially
over the northern semicircle, from 13N to 17N and between 39W to
45W. Moderate to fresh E winds are found within 120 nm north of
the center, between 42W and 46W. Fairly tranquil weather
conditions prevail across the basin.

Fresh to strong cyclonic winds associated with the circulations of
Hurricane Larry and Post-Tropical Cyclone Mindy are noted north of
29N between 56W and 64W, and between 74W and 79W. Seas in these
areas are 8-11 ft. Larger swells traveling farther away from Larry
are generating seas of 5-8 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. A tight pressure gradient over the NE
Atlantic results in fresh to strong NE winds within 180 nm of the
coasts of Morocco and Western Sahara, and the waters surrounding
the Canary Islands. Seas in this region are 7-10 ft. Gentle to
moderate easterlies prevail across the basin with seas of 4-7 ft.

For the forecast, Post-Tropical Cyclone Mindy is centered near 32.5N
75.0W at 10/0300 UTC. Mindy is bring a brief period of fresh to
strong SW to W winds N of 29N and W of 78W through early Friday
morning. Swells from Mindy will also continue through Fri
afternoon. Meanwhile, swells generated by Hurricane Larry will
continue to propagate across the waters N of 27N and E of 73W
through Fri afternoon. Seas are expected to subside into the
weekend.

$$
DELGADO
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