[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 041803
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Wed Aug 4 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 along 28W from 22N southward and
moving W at 15 to 20 kt. Scattered moderate convection is seen
from 09N to 17N between 22W and 30W.

Another Atlantic tropical wave is near 42W from 18N southward and
moving W near 20 kt. Scattered showers are present from 06N to 12N
between 40W and 45W.

A third Atlantic tropical wave is along 55W from 17N southward
into N Suriname, and moving W near 15 kt. Scattered showers and
isolated thunderstorms are occurring from 07N to 11N between 49W
and 55W.

A Caribbean tropical wave is near 76W from 15N southward to near
the Panama-Colombia border, and moving W at 15-20 kt. Interacting
with an upper-level low near Jamaica at 17N76W, scattered showers
and a few thunderstorms are noted over the central and S central
basin.

The tropical wave previously located over the Bay of Campeche and
S Mexico has moved farther W, and will mentioned in the Pacific
Tropical Weather Discussion.

...MONSOON TROUGH/ITCZ...

A monsoon trough extends from the Mauritania coast near 18N16W
through a low pressure system near 13N27W to 09N53W. Scattered
moderate convection is flaring up S of the trough along the
African coast from Senegal southward to Sierra Leone. Similar
conditions are also seen within 200 nm from neither side of the
monsoon trough between 31W and 40W, and N of the trough from 08N
to 11N between 45W and 49W.

...GULF OF MEXICO...

A cold front stretches westward from the Florida Panhandle,
passing just S of New Orleans to SE Texas. Scattered showers and
thunderstorms are evident across the N Gulf. Moderate to locally
fresh winds and seas up to 6 ft are near these thunderstorms.

A surface ridge extends west-southwestward from S Florida across
the central Gulf to central Mexico. Convergent SE winds near the
ridge axis is coupling with divergent winds aloft to trigger
scattered showers and thunderstorms over the E central Gulf and W
Florida coast. An upper-level low near the E Mexican coast at
28N98W is triggering scattered showers and isolated thunderstorms
across the W edge of the Gulf. The surface ridge continues to
sustain gentle to moderate winds and seas of 2 to 4 ft across the
central and S Gulf.

For the forecast, the frontal boundary will remain along the
northern Gulf Coast through Fri. Scattered showers and
thunderstorms will continue over the northern Gulf of Mexico this
week along and south of the front. Similar activity exists north
of 27N and east of 89W and will continue through today. Gentle to
moderate westerly winds will prevail south of the front in the
northeastern and north-central Gulf today. Moderate to fresh E
winds will pulse off the NW Yucatan Peninsula into the Bay of
Campeche every night through Sun night in association with a
diurnal trough. Elsewhere south of the front, a surface ridge
will dominate the Gulf waters over the next several days
producing gentle to moderate anticyclonic winds.

...CARIBBEAN SEA...

Enhanced by divergent winds associated with an upper-level low
near Jamaica at 17N76W, convergent trade winds are producing
scattered showers and isolated thunderstorms near the N tip of
Colombia and adjacent waters. Refer to the Tropical Waves section
above for additional convection across the basin.

The pressure gradient in the south-central Caribbean Basin has
weakened nevertheless, latest satellite scatterometer and
altimetery data indicate moderate to fresh trades and seas of 4 to
6 ft in this area. Elsewhere in the basin, gentle to moderate
trades and seas at 2 to 4 ft are evident.

For the forecast, the Bermuda high combined with lower pressures
over northern Colombia will support pulsing fresh to locally
strong winds over the south-central Caribbean through the end of
the week. Expect fresh east to southeast winds in the Gulf of
Honduras on Friday evening. Gentle to moderate trades will prevail
elsewhere.

...ATLANTIC OCEAN...

Convergent S to SW winds to the S of a cold front off the
Georgia-S Carolina coast are creating scattered showers and
isolated thunderstorms N of 27N between 76W and the E Florida
coast. Convergent trade winds are triggering similar conditions
near and N of Puerto Rico, and also near and NE of the SE
Bahamas. An upper-level low SW of the Canary Islands near 26N24W
is inducing scattered moderate convection 22N to 26N between 18W
and 24W. Refer to the Tropical Waves and Monsoon Trough/ITCZ
sections above for additional convection across the Atlantic
basin.

The subtropical ridge related to the Bermuda-Azores high persists
over the N central and W Atlantic Basin. Gentle to moderate
trades and seas at 4 to 6 ft prevail N of 13N between the African
Coast and 60W. Moderate to locally fresh SE to S winds and seas of
4 to 6 ft are seen N of 20N between 60W and the Florida-Georgia
coast. Gentle to moderate with locally fresh SE to SW winds and
seas at 4 to 7 ft are found across the rest of the basin.

For the forecast W of 65W, fresh to strong south to southwest
winds and scattered showers and thunderstorms will continue
offshore NE Florida today to the south of the cold front, which
will become a stationary front and linger along the U.S. East
Coast for the rest of the week. Fresh winds will pulse north of
Hispaniola, including the approaches to the Windward Passage, Thu
night and Fri night. Otherwise, a surface ridge associated with
the Bermuda-Azores high will persist for the next several days.

$$

Chan
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