[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181751
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Fri Aug 18 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 1200 UTC surface analysis and satellite imagery through
1700 UTC.

...SPECIAL FEATURES...

Eastern Tropical Atlantic (AL98):
Showers and thunderstorms continue to show some signs of
organization in association with a broad area of low pressure
located a few hundred miles west of the Cabo Verde Islands. Fresh
to strong winds were observed this morning by scatterometer. Environmental
conditions appear generally favorable for additional development
of this system, and a tropical depression is likely to form over
the weekend while it moves toward the west- northwest or northwest
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 medium chance of tropical cyclone development within 48 hours.

Central Tropical Atlantic (AL99):
An elongated trough of low pressure located roughly halfway
between the Cabo Verde Islands and the Lesser Antilles is
producing some disorganized showers and thunderstorms.
Environmental conditions are only marginally conducive for further
development of this system, but a tropical depression could still
form during the next couple of days while it moves west-
northwestward at 10 to 15 mph across the central tropical
Atlantic. Thereafter, upper-level winds are forecast to become
unfavorable for any further development. This system has a medium
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 tropical wave is along 33N through the low pressure mentioned
in the Special Features section, moving west with the
aforementioned low pressure (AL98) at 10-15 kt. Scattered
moderate convection is form 10N to 18N between 32W and 38W.

An Atlantic tropical wave has its axis near 52W, from 19N
southward, moving westward at 10-15 kt. Scattered moderate isolated
strong convection is from 10N to 13N between 50W and 58W.

A Caribbean tropical wave has its axis near 77W, from 26N
southward including the central Bahamas, western Cuba, Jamaica,
and NW Colombia. It is moving west at 10-15 kt. Scattered moderate
convection lags behind the wave axis, and is currently from 21N
to 25N between 70W and 73W. A recent scatterometer pass showed
reliable strong to near gale force E winds in this area,
likely the result of strong convective downdrafts.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis enters the Atlantic near 19N16W to the
low pressure (AL98) near 15N33W to 16N31N to low pressure (AL99)
near 13N44W to 10N57W. Scattered moderate convection is from 12N
to 15N between 43W and 48W.

GULF OF MEXICO...

A very weak pressure gradients exists across the Gulf of Mexico,
with a ridge axis extending across the Florida Straits. Light to
gentle winds and seas of 1-3 ft prevail.

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. The trough could form into a broad area of low
pressure in the central or W Gulf by the beginning of next week.
Some slow development of this system is possible thereafter as it
moves westward and approaches the western Gulf of Mexico coastline
by the middle of next week.

CARIBBEAN SEA...

Gentle to moderate trades prevail across the basin, with 3-6 ft
seas. Of note, locally higher seas associated with Atlantic swell
may be impacting Atlantic/Caribbean passages between the Leeward
Islands. Scattered moderate convection is in the SW Caribbean,
from 10N to 13N west of 80W.

For the forecast, moderate to fresh trade winds will prevail over
the eastern and central Caribbean during the next few days. A
strong tropical wave is likely to approach the E Caribbean this
weekend and spread fresh to strong winds and building seas over
the NE Caribbean Sat night into Tue.

ATLANTIC OCEAN...

Please refer to the SPECIAL FEATURES and the MONSOON TROUGH/ITCZ
sections above.

The subtropical ridge remains in control over most of the basin.
Anticyclonic winds are gentle to moderate north of 20N, and
moderate to fresh south of 20N. Seas are 7-8 ft from 10N to 20N
west of 54W, in an area of easterly swell. Elsewhere, seas are 4-7
ft in open waters.

For the forecast west of 55W, fresh to locally 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.

$$
Mahoney
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