[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 101721
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sat Jul 10 2021

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 31N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1700 UTC.

...TROPICAL WAVES...

A tropical wave along 35W, from 10N southward, is moving west at
10 to 15 knots. No convection is noted at this time.

A strong tropical wave along 57W, from 25N southward, is moving
quickly west at 20 to 25 kt. Scattered moderate convection is
noted from 10N to 13N between 49W and 54W. This tropical wave
marks the leading edge of the Saharan Air Layer, which based on
satellite data is north of 10N and extends east of the wave axis
to Africa. A trade wind surge is anticipated later today and
tomorrow as the tropical wave reaches the Leeward Islands and
passes through the E Caribbean.

A tropical wave along 73W, from 13N southward, is moving west at
10 to 15 knots. No convection is noted over the Caribbean at this
time. Scattered moderate convection is inland over NW Venezuela.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from Senegal and Guinea-Bissau near
12N17W to 04N25W. Segments of the ITCZ extend from 04N25W to
03N32W and from 03N37W to the coast of Brazil near 04N51W.
Scattered moderate convection is near the monsoon trough from 04N
to 12N east of 17W.

GULF OF MEXICO...

Surface observations and ASCAT data at 1500 UTC depict a 1022 mb
high pressure center near 28N85W in the NE Gulf. This high further
enhances the ridging over the Gulf caused by the subtropical
high, which is currently centered in the central Atlantic. Light
to gentle anticyclonic winds are noted in the E Gulf, with
moderate to fresh SE winds in the W Gulf. Seas are 3-5 ft
throughout the basin, except in the northwest and west-central
Gulf where seas are 4-6 ft.

For the forecast, the ridge will lift north of the area early
next week, supporting gentle to moderate winds and slight to
moderate seas through mid week. The exception will be fresh to
occasionally strong winds off the northwest Yucatan Peninsula and
eastern Bay of Campeche during overnight hours through mid week,
related to a surface trough that forms during the late afternoon
each day.

CARIBBEAN SEA...

Please see the Tropical Waves section for information on a
strong tropical wave, trade wind surge, and Saharan Air Layer
approaching the Lesser Antilles.

Strong trade winds and 8 to 12 ft seas are noted across the south
central and SW Caribbean, driven by the pressure gradient between
the subtropical high north of the area and lower pressure over
Colombia and W Venezuela. In the SW Caribbean, scattered moderate
to isolated strong convection is present south of 12N between the
coast of Colombia and the coast of Nicaragua. This convection is
likely enhanced by the East Pacific Monsoon Trough, which passes
through Panama to the 1010 mb Colombian Low at 10N75W. Moderate to
locally fresh trades are noted elsewhere in the Caribbean. Seas
are 6-9 ft off the NE coast of Honduras, and 5-7 ft within the
Gulf of Honduras. 6 to 8 ft seas prevail in the E Caribbean with 4
to 6 ft seas in the NW Caribbean.

For the forecast, high pressure centered north of the area
combined with the Colombian low will support strong to
occasionally near gale force trade winds over the south-central
Caribbean through mid week. Strong trades in the Gulf of Honduras
will diminish Sun, but fresh trades will pulse nightly through the
middle of next week. A strong, high amplitude tropical wave
approaching the Lesser Antilles today will bring the Saharan Air
Layer and a surge in wind and waves across the region through
Sun.

ATLANTIC OCEAN...

Please see the Tropical Waves section for information on a
strong tropical wave, trade wind surge, and Saharan Air Layer
approaching the Lesser Antilles.

The subtropical high centered north of the area continues to
dominate the tropical Atlantic. Moderate to locally fresh winds
veer anticyclonically along the southern half of the ridge; winds
diminish to gentle speeds over the Bahamas and far W Atlantic. In
the W Atlantic north of 22N east of 70W, seas are 3-6 ft.
Elsewhere in the basin, seas are generally 5-8 ft.

For the forecast west of 65W, high pressure extending from
Bermuda to central Florida will lift north of the area by early
next week. This will support moderate to fresh E winds south of
the ridge axis, with winds pulsing to fresh to strong along the
north coast of Hispaniola mainly during the evenings into mid
week. A large tropical wave approaching the Lesser Antilles today
will bring a surge in wind and waves to the SW waters tonight
through Mon.

$$
Mahoney
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