[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201755
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Tue Jul 20 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
1715 UTC.

...SPECIAL FEATURES...

Caribbean Gale Warning: The pressure gradient between the
subtropical high and Colombian Low/Monsoon Trough will support
gale force winds tonight off the coast of the Colombia in the
south central portion of the basin, including the Gulf of
Venezuela. Seas will build to 8-12 ft tonight, increasing further
to 9-13 ft by Wednesday morning. For more information, please see
the High Seas Forecast issued by the National Hurricane Center at
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml

...TROPICAL WAVES...

An Atlantic tropical wave extends its axis along 26W and south of
21N, moving west at 10 to 15 kt. Scattered moderate convection is
noted from 07N to 11N between 25W and 30W.

An Atlantic tropical wave extends it axis along 47W from 20N
southward, moving westward at 10 to 15 kt. This wave is
convectively inhibited by subsidence and dry air associated with
the Saharan Air Layer.

The northern extension of a tropical wave passes through the Gulf
of Honduras, along 87W and south of 18N. This tropical wave is moving
west at 10 to 15 kt. Scattered showers are noted south of 18N from
west of 84W.

...MONSOON TROUGH/ITCZ...

The monsoon trough extends from 13N17W to 08N40W. The ITCZ
extends from 07N49W to the coast of Guyana near 07N58W. Scattered
moderate convection is noted near the monsoon trough from 05N
to 10N east of 21W. Scattered showers are along the ITCZ, mainly
within 60 nm of the coast of Guyana.

GULF OF MEXICO...

A surface trough recently moved offshore into the NW Gulf, and as
of 1500 UTC extends from the coast of Louisiana near 29N91W to the
Texas coast near 27N97W. Scattered moderate convection is noted
within 80 nm of either side of the trough. Additionally, surface
observations show near gale force winds accompanying this feature.
Another surface trough is analyzed in the Bay of Campeche from
22N91W to 19N93W, with no convection at this time. Elsewhere,
surface ridging prevails across the Gulf, with gentle anticyclonic
winds and seas of 1-3 ft.

For the forecast, the ridge will continue to sink southward
through the forecast period, providing tranquil conditions across
the Gulf of Mexico for the remainder of the week. Moderate to
fresh E to SE winds will pulse Wed night to the NW of the Yucatan
Peninsula through the end of the week.

CARIBBEAN SEA...

Please refer to the Special Features section for details on a
Gale Warning for the south central Caribbean.

Scatterometer data depict strong trades prevailing across the
south central portion of the basin south of 14N between 70W and
82W, with 7-11 ft seas. Elsewhere in the basin, moderate to fresh
trades prevail with 5-8 ft seas, except in the NW Caribbean where
trades are gentle to moderate with 2-4 ft seas.

For the forecast, the Bermuda High north of the area combined
with low pressure N Colombia will support fresh to strong NE to E
winds over the central Caribbean through most of the week. Expect
an increase in areal coverage of strong wind speeds reaching to
gale force near the coast of Colombia and the Gulf of Venezuela
tonight. Fresh to strong winds will reach as far north as
Hispaniola adjacent waters. Fresh to strong E winds will occur in
the afternoons and early evenings in the Windward Passage through
midweek. Fresh to strong winds are expected to pulse in the Gulf
of Honduras Wed night and Thu night.

ATLANTIC OCEAN...

High pressure centers at 32N54W and 31N36W support gentle to
moderate anticyclonic winds across the tropical Atlantic. The only
exception is near the Windward Passage, where fresh trades are
analyzed. Seas are 4-7 ft throughout the basin, except in the W
Atlantic north of 27N and west of 65W where seas are 2-4 ft.

For the forecast, fresh to strong E winds will pulse in the
afternoons and evenings north of Hispaniola for the next several
days. Moderate to fresh trades will prevail elsewhere south of
22N. Surface ridging associated with the Bermuda High will slowly
sink southward to 27N by midweek, leading toward quiescent
conditions across the remainder of the western Atlantic.

$$
Mahoney
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