[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 241142
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
742 AM EDT 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 0600 UTC surface analysis and satellite imagery through
1130 UTC.

...SPECIAL FEATURES...

Tropical Storm Laura is centered near 20.8N 78.9W or about 150 nm
east-southeast of Cayo Largo, Cuba and 220 nm east-southeast of
the Isle of Youth moving WNW, or 295 degrees, 18 kt. The
estimated minimum central pressure is 1000 mb. The maximum
sustained wind speeds are 55 kt with gusts to 65 kt. Laura has
acquired a well pronounced and wide banding feature that consists
of numerous moderate to strong convection. This band is observed
from 17N to 19N between 78W-82W and within 30 nm of a line from
19N82W to 21N82W. Scattered moderate to isolated strong convection
makes up an outer band denoted by a 30 nm wide line that extends
from 14N76W to 17N76W to eastern Cuba near 21N76W. Similar
convection is that is within 30 nm of the center of Laura. Laura
will maintain its same motion over the next couple of days, with a
decrease in forward speed. A turn toward the northwest is
forecast by Wed. On the forecast track, the center of Laura will
move over the Caribbean Sea just offshore the southern coast of
Cuba today, and move into the southeastern Gulf of Mexico by early
Tuesday morning. Laura is then forecast to move over the central
and northwestern Gulf of Mexico Tue night and Wed. 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 27.6N 88.2W or about 100 nm
south-southeast of the mouth of the Mississippi River moving
northwest or 325 degrees at 9 kt. The estimated minimum pressure
is 1003 mb, The maximum sustained wind speeds are 50 kt with
gusts to 60 kt.Satellite imagery shows that Marco is undergoing
southwesterly vertical shear and as a result is on a weakening
trend as its center practically entirely exposed within 60 nm
to the southwest of a large area of numerous moderate convection
that exists from 28N northward to across the Florida panhandle
between Apalachicola and Destin. Scattered showers and
thunderstorms are seen from 29N to 30N between 88W-89W. Marco
is forecast to approach the coast of Louisiana this afternoon, and
then turn westward and move very close to the coast of Louisiana
through Tue night. Further weakening is expected, and Marco is
forecast to become a tropical depression late on Tue and
dissipate on Wed. Marco is expected to produce total rainfall
accumulations of 3 to 5 inches with isolated maximum amounts of 10
inches across portions of the northeast and north-central Gulf
coast through Tue. This rainfall may result in areas of flash,
urban and small stream flooding along the area. 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, that exists between a 1024 mb high
pressure center that is about 800 nm to the WNW of the Canary
Islands, and lower pressures over W Africa, supports gale-force
winds near the Canary Islands and the regional waters. The most
recent scatterometer data confirmed the gale-force winds. The
Meteo-France forecast consists of a gale warning that expires at
25/0000 UTC, in the area of CANARIAS. Please refer to the Meteo-
France High Seas Forecast, that is listed on the website:
www.meteofrance.com/previsions-meteo-marine/bulletin/grandlarge/metarea2,
for more details.

..TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 19W
from 02N to 20N, moving westward at 10 to 15 kt. Scattered
moderate to isolated strong convection is within 240 nm
either side of the axis from 05N to 08N. In addition, similar
convection is along inland the coast of Africa from 08N to
12N. This activity extends westward for 120 nm.

A Central Atlantic tropical wave has its axis along 40W from
02N to 23N. It is moving westward at 10-15 kt. This wave
is moving through a stable and dry surrounding environment.
Only isolated weak showers are noted within 180 nm either side of
the axis from 05N to 10N.

A trough extends from near 28N51W to 20N55W and to 09N55W.
Scattered showers and isolated thunderstorms are within 180 nm
west of the trough from 09N to 10N and from 14N to 23N.

A central Caribbean tropical wave has its axis along 77W south of
15N, moving westward at 10-15 kt. This wave bisects the eastern
segment of the Pacific monsoon trough that stretches from
southern Nicaragua to 11N80W and to just west of northwestern
Colombia. Small isolated showers and thunderstorms are within 60
nm east of the wave south of 13N.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the northernmost coastal
sections of Mauritania southwestward to 15N25W to 10N29N and
west to 09N38W. The ITCZ axis extends from 07N42W to 09N49W and
to just west of the above mentioned trough. Interestingly, for
this time during the hurricane season the monsoon trough and ITCZ
lack any considerable amount of convection that usually occurs
there in August. Only weakening scattered moderate convection is
noted within 180 nm south of the trough between 26W-34W.

GULF OF MEXICO...

Please see the Special Feature section above for further details
on Tropical Storm Marco and on Tropical Storm Laura soon to enter
the basin.

Other than Tropical Storm Marco, generally weak high pressure
is present over the area. Overnight ASCAT data shows gentle to
moderate winds over just about the entire Gulf, with the exception
of the areas surrounding Marco where winds are strong to near
tropical Storm force, primarily north of its center and outside
the tropical force wind radii.

Scattered moderate to strong convection is over the Bay of
Campeche south of 20N and between 92W-96W. This activity is
being enhance to some extent by the northern fringe of an
eastern Pacific tropical wave that is along 96W.

Tropical Storm Marco centered near 27.6N 88.2W 1003 mb at 5 AM
EDT is moving NW at 10 kt. Maximum sustained winds 50 kt gusts 60
kt. Marco will weaken as it reaches to near 28.06 89.2W this
afternoon with maximum sustained winds 45 kt gusts 55 kt, move
inland to near 29.2N 90.8W late tonight, then weaken to a tropical
depression over water near 29.5N 92.7W Tue afternoon and become a
remnant low and move to near 29.4N 94.5W Wed before dissipating
Wed afternoon.

Tropical Storm Laura centered near 20.8N 78.9W 1000 mb at 5 AM
EDT is moving WNW at 18 kt. Maximum sustained winds 55 kt gusts 60
kt. Laura will move to near 21.7N 81.5W this afternoon, to near
22.9N 84.6W late tonight with maximum sustained winds 60 kt gusts
75 kt, then intensify to a hurricane as it reaches near 24.5N
87.6W Tue afternoon with maximum sustained winds 65 kt gusts 80
kt. Laura will continue to intensify as it reaches to near 26.1N
90.2W late Tue night with maximum sustained winds 75 kt gusts 85
kt, to near 28.0N 92.3W Wed afternoon with maximum sustained winds
85 kt gusts 105 kt and to near 29.8N 93.3W late Wed night. Laura
will weaken to a tropical storm while moving inland to near 35.4N
91.5W early Fri. Atlantic high pressure will build westward over
the eastern Gulf in the wake of Laura.

CARIBBEAN SEA...

Please see the Special Feature section above for further details
on Tropical Storm Laura.

Outside convection associated with Tropical Storm Laura and
the tropical wave along 77W, an area of scattered isolated
thunderstorms is over the eastern Caribbean south of 15N and
east of 67W to the Windward Islands. Similar activity is over
the far northeast part of the Caribbean to the northern Leeward
Islands. Increasing activity, in the form of scattered showers and
thunderstorms moving to the southwest are seen over the British
and U.S. Virgin Islands to over eastern Puerto Rico. This
activity is being enhanced by an upper-level low that is over the
Atlantic near 22N62W. It is moving toward the west.

Tropical Storm Laura centered near 20.8N 78.9W 1000 mb at 5 AM
EDT is moving WNW at 18 kt. Maximum sustained winds 55 kt gusts 60
kt. Laura will move to near 21.7N 81.5W this afternoon and to the
far southeastern Gulf of Mexico near 22.9N 84.6W late tonight.
Laura will move farther west into the southeast Gulf of Mexico
where it will intensify into a hurricane Tue afternoon and move
into the north central Gulf through mid-week.

ATLANTIC OCEAN...

An upper-level low is near 22N62W moving westward. An upper
trough extends from the low south-southeastward to 15N61W and
to near 12N61W. Satellite imagery shows increasing scattered
showers and thunderstorms from eastern Puerto to the U.S.
and British Virgin northward to 23N and between 60W-67W.
Scattered showers and isolated thunderstorms are to the northwest
of this activity from 23N to 25N between 64W-69W. Isolated showers
and thunderstorms are elsewhere south of 30N between 58W-70W.
Scattered showers and isolated thunderstorms are quickly moving
westward over the southwest part of the area south of 25N and west
of 77W. This activity is being steered by strong low-level
easterly flow that is a result of a tight pressure gradient
between Marco and high pressure situated over the western half of
the area to the north of Laura. Expect for this activity to
increase further through tonight as Laura progresses west-
northwestward into the southeastern Gulf of Mexico.

Broad surface high pressure, anchored by 1022 mb high center at
32N72W and a 1024 mb high center at 33N33W, covers the area
north of about 27N. This high pressure area will gradually
shift southward late this week.

Tropical Storm Laura centered near 20.8N 78.9W 1000 mb at 5 AM
EDT is moving WNW at 18 kt. Maximum sustained winds 55 kt gusts 60
kt. Laura will move to near 21.7N 81.5W this afternoon and to the
far southeastern Gulf of Mexico near 22.9N 84.6W late tonight.
Laura will move farther west into the far southeastern Gulf of
Mexico near 22.5N 82.6W Mon evening. Laura will move farther west
into the southeast Gulf of Mexico where it will intensify into a
hurricane and move into the north central Gulf through mid-week.

$$
Aguirre
This weather bulletin was brought to you by:
www.nashvilleweather.net