[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 242331
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
431 PM PDT Mon Aug 24 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 21.7N 82.2W at 24/2100 UTC
or 30 nm E of the isle of Youth moving WNW at 17 kt. Estimated
minimum central pressure is 1001 mb. Maximum sustained wind
speed is 50 kt with gusts to 60 kt. Laura is now approaching the
Isle of Youth in Cuba. On the forecast track, the center
of Laura will cross western Cuba this evening and move into the
southeastern Gulf of Mexico overnight. Laura is then forecast to
move over the central and northwestern Gulf of Mexico Tuesday
night and Wednesday, and approach the northwestern coast of the
Gulf of Mexico Wednesday night. Strengthening is expected when
the storm moves over the Gulf of Mexico, and Laura is forecast
to become a hurricane by late Tuesday. Additional strengthening
is forecast on Wednesday. Heavy rainfall and storm winds in gusts
have been reported in central Cuba today. Recently, Casablanca in
Havana reported a wind gust of about 57 kt (105 km/h). The
satellite presentation of Laura has improved somewhat with deep
convection remaining over the center, and an increase in banding
over the southeastern portion of the circulation. Laura is
expected to produce total rainfall accumulations of 4 to 6 inches
with isolated maximum amounts of 10 inches over Western Jamaica,
Western Cuba and the Cayman Islands into tonight. Across the
Greater Antilles this heavy rainfall could lead to life-
threatening flash and urban flooding, and the potential for
mudslides. 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.

Tropical Storm Marco is centered near 29.0N 88.9W at 24/2100 UTC
or 10 nm ESE of the mouth of The Mississippi River moving NW at
6 kt. Estimated minimum central pressure is 1008 mb. Maximum
sustained wind speed is 35 kt with gusts to 45 kt. Gusty winds,
heavy rainfall, and lingering coastal flooding are expected from
On the forecast track, Marco will move inland over southeastern
Louisiana tonight, and across southern Louisiana on Tuesday.
Marco along portions of the Gulf Coast through this evening.
The deep convection and associated heavy rainfall has being
sheared well to the northeast of the exposed center of
circulation. As a result, weakening is expected, and Marco is
forecast to become a tropical depression tonight and degenerate
to a remnant low on Tuesday. Marco is expected to produce total
rainfall accumulations of 2 to 4 inches with isolated maximum
amounts of 7 inches across portions of the north-central Gulf
coast and southeastern United States through Wednesday. Rain
totals related to Marco near Apalachicola, Florida reached as
high as 11.81 inches on Sunday. Swells generated by Marco are
likely to affect portions of the northern Gulf Coast for the
next day or so. These swells are likely to cause life-threatening
surf and rip current conditions. 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.

..TROPICAL WAVES...

An eastern Atlantic tropical wave has its axis along 22W from
02N to 20N, moving westward at 10 to 15 kt. Scattered moderate
convection is noted near the southern end of the wave axis from
04N-08N between 20W-29W.

A central Atlantic tropical wave has its axis along 42W from 02N
to 18N. It is moving westward at 10-15 kt. This wave is moving
through a stable and dry surrounding environment. Only isolated
showers are noted near the wave axis.

A tropical wave is over the Caribbean along 83W, south of 15N,
moving westward at 10-15 kt. Scattered moderate convection is
noted across parts of Central America likely associated with the
wave and the monsoonal flow on the eastern Pacific.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the northernmost coastal
sections of Mauritania southwestward to 10N30N to 09N41W. The
ITCZ axis extends from 09N43W to 11N60W. No significant convection
is noted.

GULF OF MEXICO...

Please see the Special Feature section above for further details
on Tropical Storm Marco and on Tropical Storm Laura forecast to
move into the southeastern Gulf of Mexico overnight.

Other than Tropical Storm Marco, generally weak high pressure
is present over the area. Latest scatterometer data showed mainly
moderate northerly winds across the western Gulf, and light and
variable winds across the central Gulf S of 26N. Strong to gale
force winds are seen across the Straits of Florida due to the
pressure gradient between Laura and the Atlantic ridge. A Gale
Warning is in effect in this area through tonight.

CARIBBEAN SEA...

Please see the Special Feature section above for further details
on Tropical Storm Laura forecast to cross western Cuba this
evening.

Outside convection associated with Tropical Storm Laura, an
upper-level low is helping to induce some convective activity
over Puerto Rico and Hispaniola, including also the regional
Atlantic waters. At the surface, a trough is analyzed over the
northern Leeward Islands. The trough is forecast to move westward
across the Greater Antilles over the next 24 hours increasing
shower and thunderstorm activity.

ATLANTIC OCEAN...

High pressure of 1022 mb located near 32N72W extends a ridge
across the western Atlantic and the Bahamas. The pressure
gradient between this high pressure system and Tropical Storm
Laura brought a noticeable increase in winds across the waters S
of 27N and W of 75W, including the Straits of Florida.
Scatterometer data provided observations of fresh to strong E-SE
winds within this area, reaching gale force across the Straits
of Florida.

As previously mentioned, an upper-level is producing scattered
showers and thunderstorms across the Atlantic waters N of Puerto
Rico and Hispaniola. This system will move westward.

The pressure gradient between the E Atlantic high and the
lower pressures over W Africa supports near gale force winds
over the Canary Islands.

$$
GR
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