[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 262315
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sat Sep 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 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...TROPICAL WAVES...

A tropical wave is along 24W S of 18N, moving west at 15 kt.
convection is limited near the wave axis.

A second tropical wave is along 45W from 16N southward, moving W
at 10-15 kt. Scattered showers are noted where the wave meets the
ITCZ, particularly from 08N-11N.

A third tropical wave is along 60W S of 15N, moving W at 15 kt.
Currently, the wave appears to enhance convection over northern
Guyana and eastern Venezuela. Moisture associated with this wave
is forecast to affect the Windward Islands tonight into Sun.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes through the west coast of Africa near
18N16W to 18N20W, where there is a break in the monsoon trough.
The monsoon trough resumes at 09N20W to 11N38W. The ITCZ is from
09N47W to 08N58W. Scattered moderate convection is from 07N-09N
between 33W-36W. Scattered moderate convection is within 90 nm
either side of the ITCZ.

GULF OF MEXICO...

High pressure of 1016 mb is centered near 26N93W while a trough
extends from near Veracruz, Mexico to 25N90W. A diffluent pattern
aloft is helping to induce some convective activity over the NE
Gulf and near the trough axis. Convection has flare-up over the
Yucatan Peninsula. The most recent scatterometer data show mainly
light to gentle winds across the Gulf waters with the exception
of moderate southerly winds over the western Gulf mainly N of 23N
W of 95W.

Looking ahead, a strong cold front for this time of the year is
expected to move into the NW Gulf late Mon afternoon followed by
strong northerly winds and building seas. Winds are forecast to
reach gale force over the west-central Gulf by Tue morning, and
near Veracruz Tue afternoon and evening. Winds may reach near
storm force over the SW Gulf on Tue, with seas building to 16-18
ft. High pressure behind the front will slide eastward across
the northern Gulf through Thu night.

CARIBBEAN SEA...

A tropical wave is moving across the Windward islands. Please,
see Tropical Waves section for more details.

Scattered showers and thunderstorms are noted this afternoon
over the Greater Antilles likely due to daytime heating and sea
breeze boundaries. Upper diffluence is also helping to induce
convection over the islands and northern Central America. The
most recent satellite- derived wind data indicated fresh trades
over the south-central Caribbean, with moderate trades elsewhere.

Moderate to fresh trade winds are expected in the central
Caribbean through early Sun, becoming fresh to strong by Wed.
Moderate winds are expected elsewhere across the region.

ATLANTIC OCEAN...

Three tropical waves are between the W coast of Africa and the
Lesser Antilles. Please, see Tropical Waves section for more
details.

Over the western Atlantic, and area of showers and thunderstorms
is seen ahead of a surface through extending from 31N77W to
26N80W. TPW imagery shows abundant moisture W of 73W, including
the NW Bahamas. Upper-level diffluence supports this convective
activity.

A 1015 mb surface low is analyzed near 25N67W with a trough
extending from 28N67W to 21N66W. A well defined swirl of low
clouds is associated with the low. The low shows up well in the
latest ASCAT data. Strong E winds are north of the low from 27N-
29N between 63.5W-66W.

A large upper-level low centered near 26N35W is part of a
Tropical Upper-Tropospheric Trough (TUTT) with axis from 31N32W
to 26N35W to 17N43W to near Trinidad and Tobago Islands.
Scattered showers and thunderstorms are noted S of 22N between
55W-60W.

High pressure of 1030 mb located just NE of the Azores combined
with lower pressures over W Africa is resulting in strong N-NE
winds near the Canary Islands and off the coasts of Morocco and
Western Sahara.

For the forecast, moderate to fresh winds are expected northeast
of the Bahamas the remainder of the weekend as a surface trough
moves across the western Atlantic. A cold front will move over
the northwest part of the area Wed, then begin to weaken as it
reaches from near 31N75W to South Florida Wed night and from
31N73W to near western Cuba by late Thu. Scattered showers and
thunderstorms are expected ahead of the front.

$$
GR
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