[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112308
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Sat Aug 12 2023

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 1800 UTC surface analysis and satellite imagery through
2300 UTC.

...TROPICAL WAVES...

An eastern Atlantic tropical wave is near 24W from the Cabo
Verde Islands southward, moving westward at 5 to 10 kt.
Scattered moderate convection is noted where the wave meets the
monsoon trough from 08N to 10N between 20W and 26W.

A central Atlantic tropical wave is near 47W from 18N southward,
moving westward around 10 kt. Scattered moderate to isolated
strong convection is near the southern end of the wave axis from
05N to 07N between 46W and 49W.

A tropical wave is over the central Caribbean and extends from
eastern Cuba to northern Colombia. Its with axis is along 76W,
moving westward at 15 to 20 kt. Numerous showers, with embedded
thunderstorms, are occurring over eastern Cuba and Jamaica.
Scattered showers and thunderstorms are over northern Colombia.
Moisture associated with this system will spread over central
Cuba and the Cayman Islands tonight into Sat.

...MONSOON TROUGH/ITCZ...

A monsoon trough enters the Atlantic near the Mauritania-Senegal
border, then extends southwestward to 11N24W to 09N38W. the ITCZ
continues from 09N38W to 09N58W. Clusters of moderate to isolated
strong convection are affecting the coasts of Guinea Bissau, The
Gambia and Senegal.

...GULF OF MEXICO...

A ridge dominates the Gulf waters producing moderate to locally
fresh SE to S winds over the western Gulf, and gentle to moderate
winds over the eastern Gulf. A 1017 mb high pressure is analyzed
over the NE Gulf, while a surface trough, likely associated with
the sea breeze convergent, is helping to induce some convective
activity over Florida. Seas are generally 1 to 3 ft across the
basin, with the exception of 3-4 ft near and to the W of the
Yucatan Peninsula and in the central Bay of Campeche.

For the forecast, expect moderate to fresh SE winds overnight
across the west-central Gulf between high pressure over the
northeast Gulf and lower pressure over central Mexico. A trough
will move off the Yucatan Peninsula each night supporting fresh
to occasionally strong winds off northwest Yucatan. Elsewhere,
the ridge over the northern Gulf will support mostly gentle to
moderate winds and slight seas across the basin into mid week.

...CARIBBEAN SEA...

Satellite derived wind data provide observations of fresh to
strong winds over the central Caribbean from 12N to 16N, with
moderate to fresh trades elsewhere. Seas are 6-8 ft with the
strongest winds. In the east and western Caribbean, mainly
gentle to moderate winds prevail. Seas are 3-5 ft elsewhere
across the E and central Caribbean, and 1-3 ft over the NW
Caribbean. Late this afternoon, convection has flared up mainly
over eastern Cuba and Jamaica due to the presence of a tropical
wave.

For the forecast, fresh to strong winds over the south-central
Caribbean will expand across much of the central and southwest
Caribbean through late Sat as high pressure builds north of the
area. Except for fresh to strong winds over the Gulf of Honduras
Sun night, these winds and seas will diminish slightly into
early next week over most of the basin as a trough moving into
the Bahamas weakens the high pressure. Looking ahead, winds and
seas will increase again over the south-central Caribbean as high
pressure builds over the western Atlantic early next week.

...ATLANTIC OCEAN...

A ridge dominates most of the Atlantic forecast waters with a
1027 mb high pressure located near the Azores. A second and
weaker high pressure center of 1021 mb is situated SE of Bermuda
near 29N61W. A frontal trough is between these high pressure
centers and extends from 31N42W to 25N54W. A few showers are
near the southern end of the trough. Numerous showers and
thunderstorms are seen over the central Bahamas and parts of the
Old Bahama Channel as well as over the waters NE of the Bahamas,
particularly from 23N to 27N between 71W and 76W. An upper-level
trough exiting Florida is helping to induce this convective
activity. Moderate to fresh winds are just N of Hispaniola while
gentle to moderate winds prevails elsewhere W of 35W. Seas area
generally 3-5 ft, except 5-7 ft between 35W and 40W. Fresh to
strong winds are E of 35W, including between the Canary Islands
based on scatterometer data. Seas are 7-9 ft within these winds
according to altimeter data. An area of fresh to strong southerly
winds is noted south of the monsoon trough between 20W and 27W
where seas are in the 8-11 ft range.

A new outbreak of Saharan dust was noted over the eastern Atlantic
on Fri, while the Saharan Air Layer tracking product from CIMSS
indicates that African dust is reaching the eastern Caribbean.


Moderate to locally fresh NE winds are evident over the Cabo Verde
Islands while gentle to moderate trades are noted over the remainder
of the tropical Atlantic. Light to gentle winds are associated with
the aforementioned ridge. Seas are 6-8 ft E of 22W, and 4 to 6 ft
elsewhere E of the Bahamas.

For the forecast W of 55W, the subtropical ridge extends along
28N and will lift northward through Sat ahead of a surface trough
moving westward toward the Bahamas through early next week.
Expect moderate to fresh easterly winds south of 24N following
the trough Sun through Tue. Fresh to strong winds will pulse off
Hispaniola during the late afternoons and early evenings through
Tue.

$$
GR
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