[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 190555
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 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 0000 UTC surface analysis and satellite imagery through
0555 UTC.

...SPECIAL FEATURES...

Eastern Tropical Atlantic (AL98):
A 1007 mb low pressure is located near 16N35W, or about a few
hundred miles west of the Cabo Verde Islands. Numerous moderate to
isolated strong convection is present from 10N to 21N and between
31W and 38W. Fresh to strong winds are occurring in the northern
quadrant. 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...

An eastern Atlantic tropical wave has its axis along 35W, south of
22N with low pressure near 16N as mentioned in the Special
Features section in relation to (AL98). It is moving westward at
10-15 kt. Scattered moderate to isolated strong convection is
increasing from 10N to 21N and between 31W to 38W.

A central Atlantic tropical wave has its axis along 54W, south of
18N, westward at 10-15 kt. Scattered moderate to isolated strong
convection is seen south of 15N and between 50W and 60W. 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 at 10 to 15 mph, 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 79W, south of
26N, extending from the NW Bahamas, central Cuba and to central
Panama. It is moving westward at 10 kt. Scattered moderate
convection is evident from 18N to 27N and between 75W and 82W. A
recent scatterometer satellite pass show fresh to strong winds in
association with the deepest convection. The disturbance 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. 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 14.5N17W and continues to a 1007 mb low pressure
(AL98) near 16N35W, then to a 1008 mb low pressure (AL99) near
15N47W and then to 11N60W. Scattered moderate convection is
observed from 05N to 16N and east of 25N. The rest of the
convection is described in Special Features and Tropical Waves
sections.

GULF OF MEXICO...

The Gulf of Mexico 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, a surface ridge over the Gulf waters will support
mostly gentle to moderate winds and slight seas across the basin
through Sat night. Looking ahead, a surface trough is expected to
move across the Gulf from east to west Sun through early next
week generating fresh to strong winds and moderate seas. A broad
area of low pressure could form from this trough. Thereafter, some
slow tropical development of this system is possible 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 to isolated
strong convection between Hispaniola and Venezuela, especially
between 65W and 72W. Similar convection is also seen in the Gulf
of Gonave and off Nicaragua. 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 early next week, increasing
to fresh to strong over the NE and north-central basin Sat night
through Mon as a strong tropical wave moves across the E
Caribbean. 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. Although
environmental conditions are only marginally conducive for further
development, a tropical depression could form during the next day
or so while it moves west-northwestward at 10 to 15 kt across the
central tropical Atlantic. Thereafter, upper-level winds are
forecast to become unfavorable for any further development.

ATLANTIC OCEAN...

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

A 1008 mb low pressure (AL99) is centered near 15N47W, or roughly
halfway between the Cabo Verde Islands and the Lesser Antilles.
The sheared disturbance is producing numerous moderate to isolated
strong convection over the eastern quadrant. 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 mph across the
central tropical Atlantic. This system has a low chance of
tropical cyclone development within 48 hours.

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 elsewhere.

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 Sat. A strong
tropical wave could enhance winds and seas near the Leeward and
Virgin Islands over the weekend, and north of Puerto Rico early
next week.

$$
DELGADO
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