[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 062332
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Tue Sep 7 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 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...SPECIAL FEATURES...

Hurricane Larry is centered near 22.5N 53.9W at 06/2100 UTC or
580 nm ENE of the Northern Leeward Islands moving NW at 9 kt.
Estimated minimum central pressure is 956 mb. Maximum sustained
wind speed is 110 kt with gusts to 135 kt. The large eye diameter
is 65 nm on IR satellite imagery. Numerous moderate to strong
convection is noted within 200 nm of the southern semicircle and
scattered moderate to isolated strong convection is within 200 nm
in the northern semicircle. Seas of 12 ft or higher extend
outward 300 nm from the center except 330 nm in the NE quadrant
with maximum seas to 44 ft. On the forecast track, Larry will
continue moving northwest through Wednesday, followed by a turn
toward the north-northwest and north on Thursday. Some
fluctuations in intensity are possible during the next couple of
days. Thereafter, some gradual weakening is forecast. Swells
generated by Larry will continue to affect the Lesser Antilles,
portions of the Greater Antilles, and the Bahamas through Tuesday,
and Bermuda through late this week. Significant swells should
reach the east coast of the United States and Atlantic Canada by
midweek and continue affecting these shores through the end of the
week. These swells are likely to cause life-threatening surf and
rip current conditions. 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 WAVES...

An Atlantic Ocean tropical wave has an axis along 26W from 19N
southward, moving W at 15 kt. Scattered moderate convection is
noted from 05N to 12N between 24W and 29W.

An Atlantic Ocean tropical wave has an axis 48W from 15N
southward, moving W at 20 kt. Isolated showers are noted within 50
nm of the wave.

A Caribbean Sea tropical wave has an axis along 83W from 16M
southward, moving W at 10 kt. Scattered moderate to isolated
strong convection is noted S of 15N and W of 82W. The strongest
convection associated with this wave is moving over Nicaragua and
Honduras toward the Eastern Pacific.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends off the coast of Mauritania near 20N16W
to 13N26W to 07N37W. The ITCZ continues from 07N37W to 05N46W,
then continues W of a tropical wave near 05N48W to the coast of
French Guiana near 05N52W. Aside from the convection mentioned in
the Tropical Waves section above, scattered moderate convection is
noted from 04N to 14N between 28W and 35W, from 05N to 08N between
38W and 45W, and from 05N to 10N between 49W and 52W.

GULF OF MEXICO...

A weak 1017 mb high pressure is centered in the southeast Gulf
near 25N84W. A surface trough is noted in the Bay of Campeche from
24N91W to 19N94W. Scattered moderate to strong convection is noted
in the Bay of Campeche and the central/southeastern Gulf from 20N
to 27N between 83W and 93W, with the strongest thunderstorms noted
within 100 nm of the trough. Gusty winds and rough seas are likely
with these storms. Light to gentle winds are noted across the
basin with seas to 2 ft.

For the forecast, weak low pressure NW of the Yucatan Peninsula
is forecast to move N or NE over the central and NE Gulf of Mexico
over next few days, likely reaching the northern Gulf coast by
mid-week. Upper-level winds are currently unfavorable for tropical
development, but could become somewhat conducive for formation
before it reaches the coast. Aside from this low pressure, high
pressure will bring light to gentle winds and slight seas into
mid-week.

CARIBBEAN SEA...

See the Tropical Waves section above for details on the tropical
wave moving into the western Caribbean.

A very modest pressure gradient across the basin between high
pressure south of Bermuda and low pressure along the monsoon
trough exiting NW Colombia is yielding moderate to fresh trade
winds across the basin between 65W and 80W, where seas are
generally 4 to 7 ft. Swell from distance hurricane Larry is beginning
to enter Atlantic passages off the Leeward Islands, where seas are to
8 ft.

For the forecast, Hurricane Larry will remain well to the northeast
of the Leeward Islands tonight, then move farther north of the
area through mid week. Associated moderate to large swell will
continue to move into the region through mid week. Elsewhere,
gentle to moderate trade winds will persist, pulsing to fresh
winds off Colombia mainly at night.

ATLANTIC OCEAN...

Please see the Special Features section for details on Category 3
Hurricane Larry.

A middle to upper level cyclone is located west of Larry, is centered
near 22.5N 66W and nearly stationary. Associated upper level
divergence associated with both of these features is supporting
active scattered convection from 24N to 30N between 65W and 80W,
where moderate SW to W winds are converging at the surface south
of a weak trough from 31N69W to 30N77W.

At the surface, weak high pressure is drapped across the north of
Larry, with weak high center of 1017 mb near 25N66W. Thus,
generally outside of Larry, light to gentle wind prevails with
seas of 3 to 7 ft west of 66W. Some east swell will reach the SE
Bahamas and adjacent waters to the north this evening.

To the S and E of Larry, generally S of 20N and E of 50W,
moderate to fresh NE trades prevail. A weakening cold front is
noted in the northeast basin, from 30N14W to 25N26W to 30N40W. A
trough is south of the front from 25N27W to 24N39W. No convection
is associated with this front, and winds north of the boundary
are N and gentle to moderate.

Hurricane Larry near 22.5N 53.9W 956 mb at 5 PM EDT moving NW at
9 kt. Maximum sustained winds 110 kt gusts 135 kt. Larry will move
to 23.4N 55.0W Tue morning, 24.9N 56.3W Tue afternoon, 26.5N
57.6W Wed morning, 28.3N 59.1W Wed afternoon, 30.4N 60.7W Thu
morning. Larry will move north of the area near 33.1N 61.7W Thu
afternoon. Large swell generated by Larry will continue to
propagate across the eastern forecast waters, reaching 70W by mid
week.

$$
AReinhart
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