[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232321
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
420 PM PDT Sun Aug 23 2020

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 32N. 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...

Tropical Storm Laura is centered near 19.5N 75.2W at 23/2100 UTC
or 40 nm S of Guantanamo Cuba moving WNW at 18 kt. Estimated
minimum central pressure is 1000 mb. Maximum sustained wind
speed is 50 kt with gusts to 60 kt. Numerous moderate to strong
convection are mainly within 150 nm SW semicircle of Laura's
center. This convective activity is now affecting Haiti, Jamaica
and the waters between eastern Cuba and Jamaica. The greatest
rainfall amounts that Laura has left in Dominican Republic are:
Enriquillo, Barahona 11.7 inches (297.2 mm), La Victoria 10.2
inches (261 mm), and La Romana 10 inches (256 mm). Heavy rainfall
and life-threatening flash flooding are likely over Hispaniola,
Cuba and Jamaica. On the forecast track, the center of Laura will
move near or over southern coast Cuba tonight and Monday, and
move over the southeastern Gulf of Mexico Monday night and
Tuesday. Laura is expected to move over the central and
northwestern Gulf of Mexico Tuesday night and Wednesday. Little
change in strength is forecast while Laura moves near the
southern coast of Cuba tonight. However, strengthening is
forecast after the storm moves over the Gulf of Mexico, and Laura
is forecast to become a hurricane late Tuesday or Tuesday night.
Swells generated by Laura are affecting portions of Puerto Rico,
Hispaniola, eastern Cuba, the southeastern Bahamas and the Turks
and Caicos Islands. These swells are expected to spread across
central and western Cuba, the central and northwestern Bahamas,
and the Florida Keys during the next couple of days. Please read
the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT3.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT3.shtml for
more details, and consult products from your local weather
office.

Marco has become the third hurricane of the 2020 Hurricane
Season. It is centered near 25.8N 87.8W at 23/2100 UTC or 210 nm
SSE of the mouth of The Mississippi River moving NNW at 11 kt.
Estimated minimum central pressure is 991 mb. Maximum sustained
wind speed is 65 kt with gusts to 80 kt. Numerous moderate to
strong convection are within about 75 nm of Marco's center.
Scattered moderate isolated strong convection is elsewhere over
the Gulf of Mexico waters N of 25N E of 90W. Strong convection
has flared up over the Yucatan Peninsula likely in association
with a feeding band of Marco. On the forecast track, Marco will
be near the Louisiana coast Monday afternoon, and move near or
over the coast through Tuesday. Little change is strength is
expected over the next 24 h. Gradual weakening is expected
thereafter, and Marco could become a remnant low by Tuesday
night. Marco is expected to bring life-threatening storm surge
and hurricane force winds along portions of the U.S Gulf coast
on Mon. A Storm Surge Warning is in effect from Morgan City
Louisiana to Ocean Springs Mississippi, including Lake Borgne.
Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT4.shtml and Forecast/
Advisory at https://www.nhc.noaa.gov/text/MIATCMAT4.shtml for
more details.

The pressure gradient between a 1026 mb high pressure located
just S of the Azores Islands and lower pressures over W Africa
supports gale force winds across the Canary Islands and regional
waters. The most recent scatterometer pass confirmed the
presence of these winds. Meteo- France has issued a gale warning
through 25/0000 UTC. For more details refer to the Meteo-France
High Seas Forecast listed on their website:
www.meteofrance.com/previsions-meteo-marine/bulletin/grandlarge/metarea2

..TROPICAL WAVES...

The Hovmoller Diagram indicates the westward propagation of a
tropical wave that is reaching the coast of W Africa. Its axis
is along 15W. Scattered moderate to isolated strong convection is
noted behind the wave axis from 07N-13N.

Another tropical wave is along 37W S of 20N, moving W at 15 kt.
A rather dry and stable environment surrounds this wave. Low
level clouds are noted near the northern end of the wave axis.

A low-amplitude tropical wave continues to move westward across
the eastern Caribbean. Its axis is along 74W south of 14N.
Scattered moderate convection is noted over northern Colombia,
likely associated with the wave axis.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the coastal sections of
Mauritania near 20N16W to 16N23W to 11N30W to 10N42W. The ITCZ
extends from 10N42W to 10N62W. No significant convection is
noted.

GULF OF MEXICO...

Please, see the Special Features section above for details on
Hurricane Marco and Tropical Storm Laura.

Hurricane Marco is currently over the central Gulf of Mexico. It
is forecast to be near the Louisiana coast Monday afternoon, and
move near or over the coast through Tuesday. T.S Laura will reach
the southeastern Gulf of Mexico Monday night and Tuesday.

Outside of Tropical Storm Marco, fresh E to SE winds cover the
Florida Straits and the eastern Gulf. The SW Gulf is currently
experiencing gentle wind speeds. Moderate NE winds are in the NW
Gulf.

CARIBBEAN SEA...

Please, see the Special Features section above for details on
Tropical Storm Laura, forecast to move near or over southern
coast Cuba tonight and Monday. Laura left heavy rains and flash
flooding in Dominican Republic.

Elsewhere, moderate E-SE winds are observed over the western
Caribbean while mainly light and variable winds are over the
south-central part of the basin. Winds should gradually
decrease tonight in the eastern Caribbean as Laura progresses
farther west.

ATLANTIC OCEAN...

A Gale Warning is in effect for the Canary Islands and regional
waters. Please, see the Special Features section for details.
Also, see the Special Features section above for more information
on T.S. Laura. The pressure gradient between Laura and the
Atlantic ridge will support fresh to strong winds across the
Bahamas, SE Florida, and the Straits of Florida through late Mon.
In South Florida, breezy conditions and tropical rain showers
will be possible overnight tonight. Marine conditions are forecast
to deteriorate due to increasing winds and swell generated by
T.S. Laura.

Elsewhere, a 1021 mb high is over the west Atlantic near 31N71W.
An upper-level disturbance is inducing scattered showers and
isolated thunderstorms from 18N-25N between 55W-63W. This
convective activity is ahead of a westward moving surface trough
that is analyzed from 26N51W to 17N52W.

$$
GR
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