[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191032
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Sat Aug 19 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 0600 UTC surface analysis and satellite imagery through
1015 UTC.

...SPECIAL FEATURES...

Eastern Tropical Atlantic (AL98):
A 1006 mb low pressure is located near 15.5N35W, or about a few
hundred miles west of the Cabo Verde Islands. A tropical wave is
also analyzed with this area of low pressure, with axis along 35W.
Scattered moderate to isolated strong convection is present from
11N to 21N between 32W and 38W. Fresh to strong winds are
occurring within 200 nm over the northern semicircle.
Environmental conditions appear generally favorable for further
development of this system, and a short-lived tropical depression
is likely to form this weekend while it moves west- northwestward
or northwestward at about 10 mph across the eastern tropical
Atlantic. By early next week, upper- level winds over the system
are forecast to increase, and further development is not expected.
This system has a high chance of tropical cyclone development
within 48 hours.

Please refer to the latest NHC Tropical Weather Outlook at
www.hurricanes.gov for more details on these special features.

...TROPICAL WAVES...

A central Atlantic tropical wave has its axis along 57W (AL99),
south of 18N, moving westward at 10-15 kt. Scattered moderate to
isolated strong convection is noted from from 08N to 13N between
55W-61W. Some gradual development of this system is possible this
weekend and during the early and middle parts of next week while
it moves westward to west-northwestward across the Lesser Antilles
and over the eastern and central Caribbean Sea. The disturbance
has a low chance of development in the next 48 hours.

A western Caribbean tropical wave has its axis along 80W, south
of 26N, extending from the NW Bahamas, central Cuba and to central
Panama. The wave is moving westward at 10 to 15 kt. Scattered
moderate convection is evident across the northern half of the
wave N of 20N between 74W-78W. By early next week, a broad area
of low pressure is expected to form as the northern portion of the
wave moves across the eastern Gulf of Mexico. Some slow
development of this system is possible thereafter, and a tropical
depression could form as it moves westward and approaches the
western Gulf of Mexico coastline by the middle of next week. The
disturbance has a low chance of development in the next 48 hours.

...MONSOON TROUGH/ITCZ...

The monsoon trough reaches the Atlantic through the coast of
Senegal near 14N17W and continues to a 1006 mb low pressure
(AL98) near 15.5N35W, then to a 1008 mb low pressure (AL99) near
15.5N48W and then to 09N60W. Scattered moderate convection is
observed from 05N to 16N and east of 27N. The rest of the
convection is described in Special Features and Tropical Waves
sections.

GULF OF MEXICO...

The basin is in the western periphery of a broad subtropical
ridge over the central Atlantic. The weak pressure gradient
sustains mainly light to gentle anticyclonic winds and seas of 1-3
ft across the basin. The exception is the eastern Bay of
Campeche, south of 22N and east of 94W, where moderate to
occasionally fresh easterly winds and seas of 3-4 ft are
prevalent. A few showers are noted in the eastern Gulf and eastern
Bay of Campeche, while primarily dry conditions dominate
elsewhere.

For the forecast, the surface ridge over will continue to support
gentle to moderate winds and slight seas across the basin through
tonight. Looking ahead, an area of disturbed weather located near
the northwestern and central Bahamas is expected to move into the
Gulf of Mexico by early next week, where a broad area of low
pressure is expected to form. Some slow development of this system
is possible thereafter, and a tropical depression could form as
it moves westward and approaches the western Gulf of Mexico
coastline by the middle of next week.

CARIBBEAN SEA...

Please refer to the TROPICAL WAVES section for information on the
convection associated with the tropical wave in the western
Caribbean.

Divergence aloft due to an upper level low over eastern Cuba and
abundant tropical moisture sustain scattered moderate convection
over the eastern half of Cuba and adjacent waters N of 19N between
75W-83W. Generally dry conditions prevail elsewhere in the basin.

The pressure gradient between the ridge to the north of the
islands and lower pressures in northern South America continue to
support moderate to fresh easterly winds in the eastern and
central Caribbean. Seas in these waters are 4-7 ft. Elsewhere,
moderate or weaker winds and seas of 2-5 ft prevail.

For the forecast, moderate to fresh trade winds will prevail over the
eastern and central Caribbean through today. Winds will increase
to fresh to strong over the eastern portion of the area beginning
tonight through late Mon as a strong tropical wave moves across.
Looking ahead, a low pressure, AL99, will move NE of Puerto Rico
early next week, supporting moderate to fresh SE winds in the far
E Caribbean Mon night through mid-week. Environmental conditions
are forecast to become increasingly unfavorable for further
development of this system during the next day or two while it
moves west-northwestward at 10 to 15 kt across the central
tropical Atlantic.

ATLANTIC OCEAN...

Please refer to the SPECIAL FEATURES, TROPICAL WAVES, and the
MONSOON TROUGH/ITCZ sections above for details on convection.

An expansive subtropical ridge positioned over the central
Atlantic continues to dominate the tropical Atlantic, maintaining
fairly dry weather conditions outside of the deep tropics. Fresh
easterly trade winds are found south of 25N and west of 45W. Seas
in these waters are 5-9 ft, with the highest seas occurring near
17N58W. Fresh to locally strong SE winds are seen south of 10N and
west of 45W. Seas in the area described are 4-7 ft.

Fresh to strong N-NE winds are evident in the most recent
scatterometer satellite data off Morocco and Western Sahara, with
the strongest winds occurring in the water passages of the Canary
Islands. Meteo France advises that gusts to near gale-force are
expected in those waters. Seas of 4-7 ft are noted north of 22N
and east of 20W. Elsewhere, moderate or weaker winds and slight to
moderate seas prevail.

For the forecast west of 55W, fresh to strong tradewinds will pulse
off Hispaniola each evening into early next week. Fresh tradewinds
south of 25N will persist through the weekend. A strong tropical
wave will enhance winds and seas near the Leeward and Virgin
Islands over the weekend, and north of Puerto Rico early next
week.

$$
ERA
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