[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261205
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT Wed Aug 26 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 now Major Hurricane Laura at 26/1200 UTC is near
26.4N 91.4W. This position is about 240 nm/510 km SSE of Lake
Charles, Louisiana and about 250 nm/540 km SE of Galveston,
Texas. Laura is moving NW or 310 degrees at 13 knots. The
estimated minimum central pressure has lowered to 963 mb. The
maximum sustained wind speeds have increased to 100 kt with
gusts to 120 kt. Satellite imagery shows that Laura is quickly
becoming more symmetrical in its cloud pattern presentation as
it continues to improve. The imagery is very impressive in that
it shows very deep convection of the numerous strong type over
the entire cyclone, except near the center where an eye feature,
about 15 nm in diameter, is now evident. This convection is
observed within 210 nm of the center in the NE quadrant, within
180 nm of the center in the SE quadrant and within 90 nm of the
center in the W semicircle. Laura is growing in size and is
forecast to strengthen into a major hurricane this afternoon
near 27.4N 92.4W with maximum sustained winds 115 kt gusts 140
kt and approach the Upper Texas and southwest Louisiana coasts
this evening before moving inland near those areas tonight or
Thu morning.

Please read the latest NHC Public Advisory at
https://www.nhc.noaa.gov/text/MIATCPAT3.shtml and the
Forecast/Advisory at
https://www.nhc.noaa.gov/text/MIATCMAT3.shtml, for more details.

..TROPICAL WAVES...

A far eastern Atlantic tropical wave has its axis along 32W/33W
from 02N to 18N, moving westward at 15-20 kt. Scattered
moderate convection is within 180 nm east of the wave axis from
07N to 10N and within 120 nm west of the wave axis from 09N to
10N.

A central Atlantic tropical wave has its axis along 55W south of
18N. It is moving westward at about 17 kt. No deep convection
is noted with wave as it is moving through a stable surrounding
environment. Only isolated showers and thunderstorms are seen
west of the wave from 07N to 14N.

The previous tropical wave that was along 91W/92W is now south
of the Gulf of Tehuantepec region. Please see the eastern Pacific
Tropical Weather Discussion for details on this wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis passes through the central part of the
coastal sections of Mauritania southwestward to 15N25W to
11N33W and to 07N51W where overnight scatterometer data indicates
that it terminates. The ITCZ axis extends from just west of the
central Atlantic tropical wave to just inland the coast of
Venezuela at 08N61W. Scattered moderate to isolated strong
convection is increasing over the far eastern Atlantic south of
the trough from 09N to 17N and east of 21. Scattered moderate to
isolated strong convection is also within 30 nm of line from
10N29W to 10N24W and to 10N21W. Similar convection is
within 90 nm south of the trough between 37W-40W. Scattered
moderate convection is within 120 nm north of the trough between
34W-37W.

GULF OF MEXICO...

Please see the Special Features section above for details on
rapid intensifying Hurricane Laura, soon to be a major
hurricane.

What was the post-tropical/remnant low of Marco has now opened
up to a trough per latest ASCAT data. It extends from south of
Galveston near 27N95W northward to Galveston and to northeastern
Texas. NWS Doppler radar indicates scattered showers and isolated
thunderstorms over the NW Gulf north of 25N and west of 95W.

Otherwise outside Hurricane Laura, broad low pressure covers the
basin except for northeast of Laura where western Atlantic high
ridges westward to the far NE Gulf. The gradient between Laura and
the high pressure is allowing for fresh southeast winds to exist
over the southeastern Gulf west of 83W. These winds will diminish
today as Laura moves further away from the eastern Gulf.

Hurricane Laura centered near 26.1N 90.7W 973 mb at 5 AM EDT is
moving WNW at 13 kt. Maximum sustained winds have increased to 95
kt gusts 115 kt. Laura will strengthen into a major hurricane this
afternoon near 27.4N 92.4W with maximum sustained winds 115 kt
gusts 140 kt, and continue over the NW Gulf to along the coast
near 29.7N 93.5W late tonight with maximum sustained winds 105 kt
gusts 130 kt. Laura will move inland and weaken to a tropical
storm near 32.4N 93.7W Thu afternoon and weaken further to a
tropical depression well inland near 34.8N 92.9W late Thu night.
Expect long-period swell from Laura 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...

An elongated upper-level low is identified to be southwest
of Jamaica near 17N83W, with a shear axis stretching northeastward
to the Windward Passage and continuing from there to the Atlantic
near 22N70W. This feature has helped to destabilize the atmosphere
over much of the central Caribbean. Scattered showers and
thunderstorms are increasing from 11N to 15N between 73W-77W and
from 11N to 16N west of 77W to the coast of Honduras. Similar
activity is also increasing over the northwestern Caribbean from
16N to 22N between 78W-84W. Isolated showers and thunderstorms
are elsewhere over the basin and over sections of southern and
eastern Cuba and Hispaniola.

Atlantic high pressure will gradually shift southward through the
next few days. Expect an increase of trade winds in the central
and northeastern sections of the Caribbean Sea. A tropical wave is
expected to move across the eastern Caribbean Sea from Thu
through Fri accompanied by scattered showers and thunderstorms,
some possibly with gusty winds.

ATLANTIC OCEAN...

An upper-level shear axis extends from an elongated upper-level
over the central Caribbean northeastward to near 22N70W. A trough
extends from near 27N70W to Haiti. Scattered showers and
isolated thunderstorms are south of 24N between 67W-72W and
from 22N to 27N between 72W-77W. This activity is translating
to the west with time.

An elongated upper-level low is located near 27N34W and is slowly
moving westward. A trough extends from this low to near 14N39W.

Broad surface anticyclonic wind flow covers the rest of the Atlantic
north of 20N, with a 1021 mb high centered well to the northeast
of the area at 38N20W and a 1020 mb high over northern Georgia.
Ocean from 20N northward, from 65W eastward.

High pressure just to the north of the area will shift gradually
shift southward through the rest of this week and into Saturday.
A cold front will reach the southeastern coast of the U.S.A. late
on Saturday, and it will reach to just north of the area on
Sunday. Fresh southwest winds will precede the front.

$$
Aguirre
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