[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 041753
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sat Sep 4 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
1745 UTC.

...SPECIAL FEATURES...

Major Hurricane Larry near 16.8N 45.8W 958 mb at 04/1500 UTC
moving WNW at 13 kt. Estimated minimum central pressure is 958
mb. Maximum sustained winds 110 kt gusts 135 kt. A gradually
slower west-northwest to northwest motion is expected during the
next few days. Larry is expected to remain at major hurricane
strength through the early part of next week. Swells generated by
Larry are expected to reach the Lesser Antilles on Sunday and
will continue to spread westward to portions of the Greater
Antilles, the Bahamas, and Bermuda Monday and Tuesday.
Significant swells will likely reach the eastern United States
coastline after Labor Day. These swells are likely to cause life-
threatening surf and rip current conditions. Please consult
products from your local weather office. 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...

A tropical wave currently along 15W from 05N to 20N will emerge
off the African coast later today as it moves W at 10 to 15 kt.
Scattered moderate convection is noted from 04N to 11N, E of 21W.

An Atlantic tropical wave with an axis along 33W, from 19N
southward, is moving W at around 10 to 15 kt. Scattered showers
are noted in the vicinity of the wave axis.

A Caribbean Sea tropical wave with an axis along 70W, extends
from Hispaniola to NW Venezuela, moving W at around 15 kt.
Scattered moderate to isolated strong convection is noted E of
the wave, S of 13N between the ABC Islands and the Gulf of
Venezuela. Fresh trades are occurring on both sides of this wave.

A western Caribbean Sea tropical wave has an axis along 82W, from
13N southward, moving W at 5 to 10 kt. Scattered moderate
isolated strong convection is noted S of 12N and W of 79W,
including portions of Panama and Colombia along the interception
of the tropical wave with the Eastern Pacific monsoon trough.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coast of Guinea Bissau
near 14N16W to 08N26W, then reestablishes to the SW of Hurricane
Larry, from 10N46W to 08N50W. The ITCZ extends from 08N50W to
08N60W. Aside from convection in association with Hurricane Larry
and that associated with features depicted in the Tropical Waves
section above, scattered moderate convection is noted S of 10N
and E of 22W along the monsoon trough and S of 11 N W of 54W
along the ITCZ extending to Trinidad and Tobago.

GULF OF MEXICO...

A stationary front extends from just north of Tampa Bay, Florida,
to a 1014 mb weak low pressure near 28N86W to near Marsh Island
in Louisiana, with no scattered showers and isolated
thunderstorms in the vicinity. High pressure dominates S of the
front, anchored by a 1015 mb high centered near 27N92W. This is
leading to light to gentle winds and seas around 2 to 4 ft in the
Western Gulf and 1 to 3 ft in the eastern Gulf. The diurnal
trough across the Bay of Campeche is analyzed near 22N94W to
18N94W. A trough of low pressure over the Yucatan Peninsula is
inducing some moderate E to SE winds to the west of the
peninsula.

For the forecast, a surface trough currently over the Yucatan
Peninsula will move into the southwest Gulf through early Sun,
then move northward over the western and north-central Gulf of
Mexico through the middle of next week. Unfavorable upper level
winds should limit development through Mon, but environmental
conditions may become somewhat favorable for gradual development
Tue or Wed. Elsewhere, a stationary front over the northeast
Gulf will gradually dissipate into early Sun, while weak high
pressure dominates much of the remainder of the basin.

CARIBBEAN SEA...

See Tropical Waves section above for details on a tropical wave
entering the central Caribbean and another in the far SW basin.

Aside from convection associated with these waves, scattered
moderate isolated strong convection extends from the Gulf of
Honduras north along the Yucatan Channel in association with a
low pressure trough over Central America. Scattered moderate to
isolated strong convection is also noted north of Panama and
Colombia associated to the E Pacific monsoon trough. Otherwise,
high pressure dominates. To the east, scattered showers and
isolated thunderstorms are noted E of the ABC Islands to Trinidad
and Tobago near the ITCZ.

Moderate to fresh winds encompass the central and eastern
Caribbean, as well as the Gulf of Honduras. Locally strong trades
are occurring off the coast of Colombia, and gentle to moderate
east winds prevail in the northwest Caribbean. Seas are generally
3 to 6 ft in the central and eastern Caribbean, 4 to 7 ft
offshore Colombia, and 2 to 4 ft in the NW Caribbean.

For the forecast, Major Hurricane Larry is well to the east over
the Atlantic near 16.8N 45.8W 958 mb at 11 AM EDT moving WNW at
13 kt. Maximum sustained winds 110 kt gusts 135 kt. The closest
point of approach of the center of Larry to the Leeward Islands
is expected to be more than 500 nm by late Mon as Larry moves to
near 23N55W. However, associated rough seas will move west of 55W
tonight into early Sun, reaching the Leeward Islands and
Atlantic entrances Mon, then subside through mid-week as Larry
moves farther north of the region. Elsewhere, fresh to
occasionally strong trade winds off Colombia will diminish
through late today.

ATLANTIC OCEAN...

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

A stationary front extends from a 1012 mb low pressure near
30N76W to Cape Canaveral, Florida near 28N80W. The front
continues across the Florida Peninsula into the Gulf of Mexico.
Scattered showers and thunderstorms extend from the northern
Bahamas E to 69W. This activity is also being enhanced by an
upper-level low S of Bermuda, thus scattered convection extends
all the way E to around 58W. Moderate to fresh NE winds are
occurring to the N and W of the stalled front, with generally
gentle to locally moderate SW winds elsewhere.

To the E, high pressure dominates, with high pressure center of
1021 mb located at 29N49W, respectively. Mainly gentle winds are
occurring outside of the influence of Hurricane Larry, but some
moderate to locally fresh winds are occurring closer to the
Lesser Antilles.

For the forecast, Major Hurricane Larry near 16.8N 45.8W 958 mb
at 11 AM EDT moving WNW at 13 kt. Maximum sustained winds 110 kt
gusts 135 kt. Larry will change little in intensity as it
continues to move to the NW through mid-week with area of
tropical storm force winds expected to remain east of 65W at
least into mid-week. Rough seas in the form of large swell
generated by Hurricane Larry are expected to propagate across the
waters north of the Leeward Islands tonight and Sun, then spread
west of 65W through the early part of the week.

$$
MTorres
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