[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 030611
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Fri Sep 3 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
0500 UTC.

...SPECIAL FEATURES...

Hurricane Larry is centered near 14.1N 37.5W at 03/0300 UTC or
or about 760 nm west of the southernmost Cabo Verde Islands,
moving west at 17 kt. The estimated minimum central pressure is
985 mb. The maximum sustained wind speed speed is 75 kt with
gusts to 90 kt. Numerous moderate and scattered strong
convection is within 180 nm of the center, except 330 nm in the
SW quadrant. Larry is forecast to turn towards the west-
northwest later today, followed by a turn to the northwest on
Sunday. Additional strengthening is forecast during the next few
days, and Larry could become a major hurricane Friday night.
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.hurricnes.gov for
more details.

...TROPICAL WAVES...

An eastern Atlantic tropical wave has its axis along 21/22W from
04N-19N, with weak low pressure of 1011 mb centered along the
wave near 13N22W. This system is moving westward at 10-15 kt.
Satellite imagery shows scattered showers near the low, but
these showers have decreased significantly in coverage and
intensity during the last 6 hours. In addition, recent satellite
derived wind data indicate that the system does not have a
closed circulation. This disturbance is expected to move
westward into an environment less conducive for development
during the next couple of days, and the chances of formation
appear to be decreasing. This system could bring showers and
gusty winds to portions of the southernmost Cabo Verde Islands
during the next several hours. The disturbance has a low chance
of tropical cyclone formation during the next 48 hr.

A tropical wave has its axis along 59/60W south of 20N to inland
South America, moving W at 15-20 kt. Scattered moderate to
strong convection is along and within 150 nm east of the wave
from 08N to 13N. Strong E winds are east of the wave axis from
10N-13N. Periods of heavy rainshowers and gusty winds are
possible today over Trinidad and Tobago as well as Grenada.

A Caribbean tropical wave has its axis along 77/78W south of
14N, moving westward near 15 kt. This tropical wave is rather
ill-defined and latest model guidance does not reveal any
signals with this wave. Only a few isolated showers are seen
east of the wave axis over northern Colombia.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coast of Senegal near
14N17W to low pressure of 1011 mb near 13N22W to 12N30W. It is
interrupted by Hurricane Larry. It then resumes to the SW of
Larry at 11N41W to 08N51W. The ITCZ continues from 08N51W to
08N58W. Aside from the convection already mentioned in the
sections above, isolated moderate convection is seen from
05N-12N between 42W-55W.

GULF OF MEXICO...

As of 0300 UTC, a cold front extends from Panama City, Florida
to New Orleans, Louisiana. One or two isolated showers or
tstorms have been appearing from time to time in the vicinity of
the front during the past few hours. Elsewhere, isolated showers
and tstorms are over portions of the west-central and southwest
Gulf of Mexico. A 1015 mb high pressure is centered near 24N85W. A
recent ASCAT pass shows moderate west winds in the NE Gulf, to
the south of the front. The high pressure ridge, containing light
to gentle winds, extends from the high pressure northwestward to
SW Louisiana. The ASCAT pass also shows moderate E to SE winds
prevailing over the southwest Gulf, except for fresh E winds off
the northwest coast of the Yucatan Peninsula. Seas are 3-5 ft west
of Yucatan and in the southwest to west-central Gulf. Seas are 1
to 3 ft elsewhere.

For the forecast, the cold front will stall over the far
northeast Gulf through today and gradually dissipate over the
weekend. This pattern will maintain light to gentle breezes over
most of the Gulf, with slight seas, except for fresh winds
expected to pulse northwest of the Yucatan Peninsula at night
through Sat. A surface trough currently over the Gulf of Honduras
and portions of Central America could move over the southwestern
Gulf of Mexico late this weekend, but unfavorable upper-level
winds are likely to limit significant development while the system
moves northwestward or northward over the western Gulf of Mexico
early next week. There is a low chance of tropical cyclone
development over the next 5 days.

CARIBBEAN SEA...

See the tropical waves section above for details on a tropical
wave that could bring gusty showers today to the southeastern
Caribbean.

Currently, scattered thunderstorms are noted near southwestern
Haiti. A recent ASCAT pass shows fresh trades in the
south-central Caribbean and Gulf of Honduras, with gentle to
moderate trades elsewhere. Fresh winds are moving into the far
eastern Caribbean in association with the tropical wave along
59/60W. Seas are 4 to 6 ft in the areas of fresh winds, and 2 to
4 ft elsewhere. Moderate to fresh trade winds will continue over
the south-central Caribbean through Sun. Fresh to locally strong
east to southeast winds are expected in the Gulf of Honduras at
night through the weekend.

A surface trough over the Gulf of Honduras and portions of
Central America is producing disorganized scattered moderate
convection over northern Nicaragua and Honduras, and over water
from 16N-19N between 81W-85W. This system is expected to move
west-northwestward across Central America and the Yucatan
Peninsula, bringing heavy rains to that area during the next
couple of days. The disturbance could then move over the
southwestern Gulf of Mexico late this weekend.

Hurricane Larry will move to near 19N50W Sun morning, then move
well northeast of the Leeward Islands late Mon. Large swells
generated by Hurricane Larry are expected to propagate across
the waters east of the Leeward Islands on Sun, likely spreading
beyond 65W Mon and Mon night. Some of the swell may get through
the NE Caribbean passages, but the larger waves should stay over
the Atlantic.

ATLANTIC OCEAN...

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

A cold front extends from 32N76W to the Florida/Georgia border
near 30.5N81.5W. Moderate to fresh winds prevail on both sides
of the front. An upper-level trough extends along the U.S.
eastern seaboard, helping to enhance scattered showers and
tstorms from 25N-31N between 73W-80W. A large upper-level low
centered near 28N67W is producing scattered tstorms north of 24N
between 63W-70W. High pressure ridging prevails farther east,
between 35W-65W, north of 20N, anchored by a 1024 mb high near
31N47W. Over the NE Atlantic, a surface trough extends from 31N24W
to 25N32W. Scattered moderate convection is north of 30N near the
trough axis. Gentle anticyclonic winds prevail within a few
hundred nm either side of a surface ridge axis, which runs from
31N47W to 24N70W to 24N80W. Wind speeds south of 23N between 35W-
60W are fresh, except strong to hurricane force close to Larry.
Outside of swells from Larry, seas are currently 4 to 6 feet
across most of the Atlantic.

For the forecast, the cold front will weaken as it advances
slowly eastward across the northern waters W of 70W Sat through
Sun night. Looking ahead, Hurricane Larry will move to near
20N52W Sun evening, then move well NE of the Leeward Islands
late Mon. At a minimum, large swells generated by Hurricane
Larry are expected to propagate across the waters east of the
Leeward Islands on Sun, likely spreading west of 65W Mon and Mon
night.

$$
Hagen
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