[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 051724
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sun Sep 5 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
1700 UTC.

...SPECIAL FEATURES...

Category Three Hurricane Larry is centered near 19.5N 49.7W at
05/1500 UTC or 760 nm E of the Northern Leeward Islands moving NW
at 11 kt. Estimated minimum central pressure is 955 mb. Maximum
sustained wind speed is 110 kt with gusts to 135 kt. The eye
diameter is 45 nm on IR satellite imagery. Numerous moderate to
strong convection is noted within about 150 nm of center. Seas of
12 ft or higher extend within 300 nm in the N semicircle and 240
nm in the S semicircle, with seas as high as 46 ft. On the
forecast track, a northwestward motion with a slight decrease in
forward speed is expected during the next few days. Little change
in strength is forecast during the next few days, although
fluctuations in intensity will be possible. Larry is a large
hurricane, and is expected to remain a major hurricane through
the middle of this week. Swells generated by Larry are expected
to reach the Lesser Antilles today, and will spread westward to
portions of the Greater Antilles, the Bahamas, and Bermuda on
Monday and Tuesday. Significant swells will likely reach the east
coast of the United States and Atlantic Canada by midweek. These
swells are likely to cause life-threatening surf and rip current
conditions. Based on an altimeter pass, seas of 8-9 are noted from
12N-20N near 55W. 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 east Atlantic tropical wave has an axis along 19W/20W from 03N
to 19N, moving W around 5-10 kt. Scattered moderate convection is
noted from 10N to 14N between 17W and 20W.

An Atlantic Ocean tropical wave has an axis along 36W/37W from
03N to 16N, moving W at 5-10 kt. The wave is situated at the
leading edge of a Saharan dust plume. As a result, no significant
convection is noted with the wave at this time.

A Caribbean Sea tropical wave has an axis along 76W, stretching
from eastern Cuba to NW Colombia, moving W at 10 kt. The wave is
likely enhancing scattered moderate convection over northern
Colombia and NW Venezuela. Fresh to locally strong E winds are
occurring E of the wave axis in the south-central Caribbean.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic ocean near the Mauritania/
Senegal border at 16N16W to 07N28W. The ITCZ extends from 07N28W
to 04N40W, then continues W of a tropical wave from 04N38W to the
coast of Guyana and Venezuela near 08N60W. Aside from the
convection mentioned in the Tropical Waves section above,
scattered moderate convection is observed from 06N-08N between
20W-26W, and from 04N-08N between 42W and 46W.

GULF OF MEXICO...

Disorganized showers and thunderstorms over portions of Central
America and the Yucatan Peninsula are associated with a surface
trough and an upper-level disturbance. A 1011 mb low pressure is
analyzed near 19N91W at 1200 UTC. Locally heavy rains are likely
to continue today over that area in association with this system,
forecast to move northwestward over the southwestern Gulf of
Mexico later today, then move slowly northward or northeastward
over the western or central Gulf of Mexico. Upper-level winds are
only expected to be marginally conducive for tropical cyclone
formation, but some slow development is possible while the system
moves across the Gulf of Mexico through the middle of the week.
The latest Tropical Weather Outlook states that this system has a
low chance of tropical cyclone formation through 5 days. For more
information please see hurricanes.gov

Elsewhere in the Gulf of Mexico, a stationary front persists over
the NE Gulf, extending from northern Florida to near Mobile,
Alabama. Isolated showers are near the frontal boundary. A pair of
1015 mb high pressure centers are located near 26N92W and 24N84W,
and are the dominant weather features in the Gulf of Mexico this
morning. A diffluent pattern aloft supports scattered showers and
thunderstorms over the NE Yucatan peninsula and adjacent waters,
including Cozumel and Cancun. Light to gentle winds and slight
seas encompass the basin, except NW of the Yucatan peninsula where
gentle to moderate E-SE winds are occurring. These winds are
likely related to a thermal trough that usually develops over the
Yucatan peninsula during the night hours, and moves across the Bay
of Campeche during the morning hours.

For the forecast, the stationary front over the northeast Gulf
will dissipate today, while a ridge will dominate much of the
Gulf region producing mainly light to gentle winds.

CARIBBEAN SEA...

See the Tropical Waves section above for details on a tropical
wave in the central Caribbean.

Recent scatterometer data provide observations of fresh to locally
strong trades over the south-central Caribbean, and moderate to
fresh winds elsewhere, except light to gentle winds in the lee of
Cuba, and in the SW Caribbean south of 10N-11N. Seas are 4-7 ft S
of 18N E of 80W, and 3-5 ft S of 18N W of 80W, including the Gulf
of Honduras. Seas of 1-3 ft dominates the NW Caribbean.

An upper-level extending from Hispaniola to eastern Panama is
helping to induce scattered showers with embedded thunderstorms
over the south-central Caribbean, mainly S of 15N between 70W-81W.
Similar convective activity is noted over the Gulf of Honduras
and the NW Caribbean under a diffluent pattern aloft.

For the forecast, Hurricane Larry will remain well to the northeast
of the Leeward Islands through Mon, then move farther north of
the area through mid week. For more information, please refer to
the Special Features section above. Elsewhere, gentle to moderate
trade winds will persist, pulsing to fresh winds off Colombia mainly
at night.

ATLANTIC OCEAN...

Attention remains focused of Major Hurricane Larry. Please, see
the Special Features section for details. Larry is forecast to
approach Bermuda during the next several days, likely as a major
hurricane, bringing a risk of strong winds, heavy rainfall, and
coastal flooding to the island by the middle of this week. While
it is too soon to determine the magnitude of these hazards and
potential impacts on Bermuda, interests there should closely
monitor the latest forecast updates during the next several days.

A weak stationary front enters the forecast area near 31N70W, then
continues SW over northern Florida into the NE Gulf of Mexico.
Isolated showers and light winds are near the frontal boundary.
Otherwise, high pressure dominates most of the Atlantic forecast
waters, outside of the influence of Hurricane Larry. This is
leading to gentle to moderate winds across the basin. Farther to
the east, a belt of moderate to fresh trades is noted roughly from
13N-20N E of 38W, and just N of the Cabo Verde Island to the W
coast of Africa. A cold front crosses between Madeira and the
Azores islands and extends along 30N23W to 29N30W to beyond
31N35W. A broken band of mainly low clouds with isolated showers
is related to the front.

For the forecast, hurricane Larry Larry will move to 20.5N 51.1W
this evening, 21.9N 52.7W Mon morning, 23.0N 54.0W Mon evening,
24.3N 55.4W Tue morning, 25.7N 56.7W Tue evening, and 27.3N 58.1W
Wed morning.

$$
GR
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