[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171809
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Sat Jul 17 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
1630 UTC.

...TROPICAL WAVES...

An Atlantic tropical wave is near 34W from 21N southward and
moving W at 5 to 10 kt. This wave remains embedded in the Saharan
Air Layer, which dust and dry air is limiting the convection to
scattered moderate from 03N to 07N between 28W and 34W.

Another Atlantic tropical wave is just E of the Lesser Antilles
along 59W from 20N southward, and moving W near 10 kt. This wave
is at the western edge of the Saharan Air Layer, and only
isolated showers and thunderstorms are observed over the Windward
and southern Leeward Islands.

A third tropical wave over the western Caribbean is near 79W from
16N southward across Panama, and moving W near 15 kt. Moderate
vertical shear is enhancing scattered showers and isolated
thunderstorms over Panama, and the E coast of Honduras and
Nicaragua.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends through the Gambia coast at 12N16W to
06N37W. Then ITCZ continues from 06N37W to 05N48W, just E of
Suriname-Brazil border. Scattered moderate to isolated strong
convection is seen from 04N to 11N between the African coast and
28W.

...GULF OF MEXICO...

An upper-level trough extending northward from the Bay of Campeche
across the N Gulf continues to trigger scattered showers and
isolated thunderstorms near New Orleans from 28N to 30N between
87W and 90W. Coupling with a surface trough over the Bay of
Campeche, scattered showers and thunderstorms are occurring at the
central Gulf and Yucatan Peninsula; including the Yucatan Channel.
Locally moderate to fresh winds and seas at 3 to 5 ft are
possible in these thunderstorms.

Otherwise, a surface ridge extending southwestward from the
Bermuda High across N Florida and the N Gulf is supporting light
to gentle ESE to SE winds and seas of 1 to 3 ft across the Gulf.

For the forecast, the Bermuda High extends a ridge southwestward
across the SE CONUS. As the ridge sinks southward during the next
few days, tranquil conditions will prevail across the Gulf of
Mexico. No tropical cyclone activity is expected over Gulf through
at least Wed night.

...CARIBBEAN SEA...

Enhanced by modest vertical wind shear, convergent trade winds
are producing scattered showers and isolated thunderstorms over
western Cuba and the central W basin. Refer to the Tropical Waves
section above for additional convection in the basin.

Tight pressure gradient between the Atlantic ridge and the
Colombian low continues to create fresh to strong trades and seas
of 8 to 11 ft across the central and S central Caribbean. Gentle
to moderate trades and seas of 2 to 4 ft are seen along the W
Caribbean. Moderate to locally fresh trades and seas of 4 to 6 ft
prevail across the rest of the basin.

For the forecast, the Bermuda High north of the area and lower
pressure over N Colombia continue to support fresh to strong NE to
E trades over the S central and SW Caribbean. These winds will
continue through early next week and increase in speed and areal
coverage Mon night through Wed night, reaching Hispaniola adjacent
waters. Elsewhere, NE trades will become fresh to strong tonight
and Sun night in the Windward Passage. No tropical cyclone
activity is expected over the Caribbean or tropical N Atlantic
through at least Wed night.

...ATLANTIC OCEAN...

An upper-level low SW of Bermuda near 29N69W is triggering
scattered showers N of 25N between 63W and 72W. A surface trough
extends southwestward from a low W of Bermuda to near the NW
Bahamas at 28N77W. Scattered showers and isolated thunderstorms
are occurring across S Florida and the NW Bahamas. Refer to the
Tropical Waves and Monsoon Trough/ITCZ sections above for
additional convection across the Atlantic.

The persistent surface ridge across the central Atlantic is
sustaining light to gentle winds and seas of 2 to 4 ft N of 24N
between 28W and the Georgia-Florida coastline. Moderate to locally
fresh trades and seas of 4 to 6 ft are present from 12N to 24N
between 24W and the Lesser Antilles, and also near the Canarias
Islands N of 23N between the NW African coast and 20W. Gentle to
moderate trades and seas of 3 to 5 ft prevail for the rest of the
Atlantic.

For the forecast W of 45W, fresh to strong E winds will occur
afternoons and early evenings north of Hispaniola for the next
several days. Ridging associated with a weak Bermuda High will
slowly sink southward to 27N by Wed, leading toward quiescent
conditions across the remainder of the SW N Atlantic waters. No
tropical cyclone activity is expected in the area through at least
Wed night.

$$

Chan
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