[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251205
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT Tue Aug 25 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
1145 UTC.

...SPECIAL FEATURES...

The center of Tropical Storm Laura at 25/0900 UTC is near 22.9N
85.7W, or about 75 nm west of the western tip of Cuba or 590 nm
southeast of Lake Charles, Louisiana moving WNW or 290 degrees
at 15 kt. The estimated minimum central pressure is 995 mb. The
maximum sustained wind speeds are 55 kt with gusts to 65 knots.
Satellite imagery shows that Laura is quickly becoming better
organized as evident by a CDO feature that has developed over the
center and large banding features in the SE semicircle of Laura.
Convection is described as the numerous moderate to strong type
from 22N to 24N between 84W-86W, and of the scattered moderate
type that makes up a large band from 19N to 22N between 84W-87W.
Scattered moderate to isolated strong convection is seen from 18N
to 19N between 84W-87W. Laura will continue its present motion
today, then a toward the northwest is forecast by Wed, and a
northwestward to north-northwestward motion should continue
through Wed night. On the forecast track, the center of Laura will
move away from Cuba and over the southeastern Gulf of Mexico this
morning. Laura is then forecast to move over the central and
northwestern Gulf of Mexico tonight and Wed, approach the Upper
Texas and Southwest Louisiana coasts on Wed night and move inland
near those areas on Thu. 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.

The surface pressure gradient, that exists between a 1026 mb
high pressure center that is about 1100 nm to the WNW of the
Canary Islands, and lower pressures that are in W Africa,
supports gale-force winds near the Canary Islands and the
regional waters. The Meteo-France forecast consists of a gale
warning 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/m
etarea2, for more details.

..TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 24W from
02N to 20N, moving westward at 10-15 knots. A large area of
scattered moderate to strong convection is noted ahead of the
wave from 05N to 09N between 25W-30W. Scattered moderate to
isolated strong convection is within 60 nm of line from 07N30W to
07N34W and to 06N38W.

A central Atlantic tropical wave has its axis along 45W/46W from
02N to 18N, moving westward at about 17 kt. This wave is remains
within a rather dry and stable environment. Only scattered
moderate convection is seen within 60 nm of the axis from 07N to
09N.

A trough is analyzed from near 23N61W to 16N62W and to just inland
Venezuela at 10N63W. This trough was highlighted by an overnight
ASCAT pass that nicely depicted to the northeast to southeast wind
shift across it. These winds were of gentle to moderate speeds.
Isolated showers and thunderstorms are within 60 nm west of the
trough from 17N to 19N. Similar activity trails the trough within
30 nm of a line from 10N56W to 14N59W to 16N61W.

The northern portion of an eastern Pacific tropical wave along 86W
extends northward to across western Nicaragua and central
Honduras, while at the same time the eastern Pacific monsoon
trough extends from El Salvador east-southeastward across central
Nicaragua and continues to northwestern Colombia. Earlier scattered
showers and thunderstorms that were over Honduras and Nicaragua
have significantly diminished. Isolated showers and thunderstorms
are over southern Nicaragua.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the northernmost coastal
sections of Mauritania to 18N20W to 12N34W and to 10N47W, where
recent scatterometer data indicates that it transitions to
the ITCZ and continues to coast of Venezuela near 09N61W. Aside
from convection related to the tropical waves, only scattered
moderate convection is within 120 nm south of the trough between
26W-27W.

GULF OF MEXICO...

Please see Special features section above for details on
intensifying Tropical Storm Laura.

Outside intensifying Tropical Storm Laura, the post-tropical/remnant
low of Marco is near 29N91W with a pressure of 1008 mb and moving
westward at 9 kt. The low is losing its identity with time and
will soon transition to a trough as it continues westward for the
next 24 hours or until it dissipates. An overnight ASCAT pass
indicated fresh winds on either side of the low, with greater
coverage of these winds east of the low where the gradient is the
tightest between the low and the western periphery of Atlantic
high pressure.

Isolated showers are near the low. Elsewhere, the surface analysis
suggests broad low pressure over the area north of 25N west of
86W, while Atlantic high pressure ridges westward to the far NE
Gulf.

Scattered moderate to strong convection is confined over the far
SW Gulf from 19N to 22N and west of 95W to just inland the coast
of Mexico. Scattered moderate to isolated strong convection is
from 22N to 24N west of 96W to just inland the coast of Mexico.
Scattered shower and isolated thunderstorms are seen over the
eastern Gulf to the northeast of Laura from 25N to 27N and
between 83W-86W.

Tropical Storm Laura centered near 22.9N 85.7W 995 mb at 5 AM EDT
is moving WNW at 15 kt. Maximum sustained winds 55 kt gusts 60
kt. Laura will intensify to a hurricane near 23.8N 87.9W this
afternoon with maximum sustained winds 65 kt gusts 80 kt. Laura
will continue to intensify as it reaches near 25.1N 90.6W late
tonight with maximum sustained winds 80 kt gusts 90 kt, and
continue over the NW Gulf to near 26.8N 92.7W Wed afternoon with
maximum sustained winds 95 kt gusts 115 kt, reach near 29.3N 93.7W
late Wed night with maximum sustained winds 100 kt gusts 120 kt
before moving inland and weaken to a tropical storm near near
32.1N 93.7W Thu afternoon. Laura will weaken to a to a tropical
depression well inland near 34.5N 93.0W late Thu night. Expect for
long-period swell to impact most of the basin through Thu.
Atlantic high pressure will build westward over the eastern Gulf
in the wake of Laura.

CARIBBEAN SEA...

A tropical wave has moved inland Central America with axis along
86W. See above for more information.

An upper-level low is identified to be near 15N73W, with a
trough south-southwest to near 09N76W. Increasing scattered
moderate to isolated strong convection is noted south of 16N and
between 76W-81W and also south of 13N west of 81W. Isolated
showers and thunderstorms are elsewhere over the basin.

Tropical Storm Laura centered about 45 nm north of the western
tip of Cuba will intensify into a hurricane near 23.8N 87.9W this
afternoon with maximum sustained winds 65 kt gusts 80 kt.
Otherwise, Atlantic high pressure will gradually shift southward
through the next few days leading to an increase of trade winds
over the central and northeast sections of the Caribbean. A
tropical wave is expected to move across the eastern Caribbean
Thu through Fri.

ATLANTIC OCEAN...

An upper-level trough extends north-northeast from an upper low
that is over the central Caribbean to near 25N70W. The northern
section of an eastern Caribbean Sea trough extends to near 24N61W.
Scattered showers and thunderstorms are quickly moving westward
south of 24N between 65W-73W. Isolated showers and thunderstorms
are elsewhere south of 27N and 78W.

The southern tail-end of a central Atlantic cold front reaches to
near 30N59W. Scattered showers and thunderstorms are noted north
of 30N east of the front to near 50W. This activity is moving
east-southeastward.

A 1021 mb high center is located at 32N73W, while a 1020 mb high
center is at 32N35W. Broad surface rather weak high pressure is
present north of about 22N.

Tropical Storm Laura centered near the western tip of Cuba will
continue to advance into the Gulf of Mexico today while it
intensifies to a hurricane. Otherwise, high pressure just north of
the area will gradually shift southward through the rest of this
week and into Sat. Fresh to strong southeast winds over the
southwest part of the area will diminish to mainly moderate speeds
on Tue.

$$
Aguirre
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