[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170555
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 UTC Thu Aug 17 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
0535 UTC.

...SPECIAL FEATURES...

Invest 99L: A 1009 mb low pressure is located near 12N39W, or
about 760 nm west-southwest of the Cabo Verde Islands. Scattered
moderate and isolated strong convection is noted from 05N to 15N
and between 35W and 53W. Environmental conditions appear conducive
for gradual development of this system, and a tropical depression
could form during the next several days while it moves west-
northwestward at 10 to 15 mph across the central tropical
Atlantic. This system has a medium chance of tropical development
in 48 hours.

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

...TROPICAL WAVES...

An eastern Atlantic tropical wave has its axis along 25W, south of
19N, moving westward at 10 kt. This disturbance (Invest 98L) is
producing a large area of disorganized showers and thunderstorms
near and to the southwest of the Cabo Verde Islands. Further
development of this low is possible while it moves toward the
west-northwest or northwest at around 10 mph across the eastern
tropical Atlantic, and a tropical depression could form over the
weekend before environmental conditions become unfavorable for
development early next week. This system has a low chance of
tropical development in 48 hours.

A central Atlantic tropical wave has its axis along 43W, south of
20N, moving westward at 10-15 kt. Please see the Special Features
section for information of convection near this tropical wave.

An eastern Caribbean tropical wave has its axis along 65W, south
of 20N, moving westward at 10-15 kt. Scattered moderate convection
is noted near the northern portion of the wave.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic through the coast of
Mauritania near 20N16W and continues southwestward to 13N27W to a
1009 mb low pressure near 12N39W and to 12N51W. The ITCZ extends
from 12N51W to 12N60W. See Tropical Waves section for details on
convection.

GULF OF MEXICO...

The Gulf of Mexico is in the western periphery of an expansive
subtropical ridge positioned between Bermuda and the Azores.
Scattered showers and isolated thunderstorms are affecting the
eastern Bay of Campeche, associated with convection that fired up
over the Yucatan peninsula earlier today. A few showers and
isolated thunderstorms are also noted in the eastern Gulf of
Mexico due to favorable upper level dynamics. No deep convection
is observed in the rest of the basin. The weak pressure gradient
allows for moderate or weaker winds and 1-3 ft across the entire
Gulf of Mexico.

For the forecast, a surface trough will continue to support isolated
thunderstorms across the N-central and NE Gulf tonight and
tomorrow. A surface ridge over the central Gulf will support
mostly gentle to moderate winds and slight seas across the basin
through the weekend. Looking ahead, a broad area of low pressure
could form in the central or W Gulf by the beginning of next
week.

CARIBBEAN SEA...

Isolated showers and thunderstorms are present in the SW Caribbean
Sea and east of the Yucatan peninsula. Similar convection is seen
in the Gulf of Gonave. Otherwise, no deep convection is noted in
the remainder of the basin. The pressure gradient between the
subtropical ridge in the central Atlantic and lower pressures in
NW Colombia support fresh to strong easterly trade winds in the
central Caribbean. A recent scatterometer satellite pass indicate
that the strongest winds are occurring within 75 nm of northern
Colombia. Seas of 4-8 ft are found in the central Caribbean.

Moderate to fresh easterly winds are evident in the eastern
Caribbean, Windward Passage and Gulf of Honduras, along with seas
of 3-5 ft. Elsewhere, slight to gentle winds and slight seas
prevail.

For the forecast, fresh to locally strong tradewinds will prevail
across the central Caribbean through tonight. The pressure
gradient between the Bermuda High and the Colombian Low will
loosen by tomorrow morning, resulting in a slight decrease in
winds over the area for the next few days. Gentle to moderate
tradewinds will prevail elsewhere.

ATLANTIC OCEAN...

An expansive subtropical ridge dominates the tropical Atlantic,
extending from the far NE Atlantic to offshore Florida. Scattered
moderate to isolated strong convection is seen west of 73W and
north of 25N due divergence aloft associated with a upper level
trough over the SE United States. A recent scatterometer satellite
pass show fresh to strong southerly winds in the areas with the
strongest convection. Seas in the waters described are 3-5 ft.

The pressure gradient between the 1025 mb subtropical ridge and
lower pressures in the deep tropics support fresh to locally
strong easterly winds south of 27N and between Africa and the
Bahamas. Wave heights in these waters are 5-9 ft, with the
highest seas occurring within 120 nm of 22N32W and 20N55W.
Elsewhere, moderate or weaker winds and moderate seas are
prevalent.

For the forecast W of 55W, fresh to locally strong trade winds
will pulse off Hispaniola each evening through the next several
days. Fresh tradewinds will develop south of 25N starting Thu and
diminishing again on Sat. A cold front will approach the NW waters
then stall, but fresh SW winds ahead of the cold front can be
expected Thu and Fri in the NW waters. Gentle to moderate winds
will prevail elsewhere.

$$
DELGADO
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