[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182318
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 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 1800 UTC surface analysis and satellite imagery through
2300 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. A
tropical wave associated with this broad low pressure area has is
axis along 33W/34W from 10N to 22N with a 1008 mb low along it
near 16N. The shower and thunderstorm activity is of the
scattered moderate to isolated strong type intensity. It is
increasing from 13N to 20N between 30W-36W and from 10N to 13N
between 30W-38W. Fresh to strong winds are within this area as
observed several hours ago in ASCAT data passes. 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
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 is located roughly halfway
between the Cabo Verde Islands and the Lesser Antilles. A 1009 mb
low is analyzed along the trough near 14N45W. It is producing
some disorganized scattered moderate to strong convection from
13N to 15N between 44W-47W. 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 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...

An eastern Atlantic tropical wave has its axis along 33N/34W
from 10N to 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 13N to 20N between 30W-36W and from
10N to 13N between 30W-38W.

A central Atlantic tropical wave has its axis along 52W/53W from
06N to 19N moving westward at 10-15 kt. Scattered moderate to
isolated strong convection is ahead of the wave from 10N to 13N
between 52-58W.

A central Caribbean tropical wave has its axis along 78W from
26N southward including the central Bahamas, east-central Cuba,
western Jamaica, and southern Panama. It is moving west at 10-15
kt. Isolated showers and thunderstorms are within 120 nm west
of the wave south of 13N. Fresh northeast to east winds near
the wave south of 13N.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis enters the Atlantic near 19N16W to low
pressure (AL98) near 16N34W 1008 mb and to 14N39W to low
pressure (AL99) near 14N45W 1009 mb to 10N57W. Convection is
described with the Special Features and with the tropical waves.

GULF OF MEXICO...

Generally weak high pressure over the area is allowing for a
a weak pressure gradient to exist. As a result, light to gentle
winds and seas of 1-3 ft remain over the basin.

For the forecast, the high pressure will support mostly gentle
to locally 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.
Thereafter, some slow development of this system is possible 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...

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 confined to the
southwestern Caribbean from 10N to 13N and west of 80W. This
activity is being enhanced by the eastern segment of the eastern
Pacific monsoon trough that is located there.

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. A low pressure (AL99) trailing this wave will move
NE of Puerto Rico afterwards, supporting moderate to fresh SE
winds in the far eastern Caribbean Mon night and through the
middle of next week.

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. The northern part of a tropical
wave that is along 78W in the Caribbean Sea reaches north-
northeastward along 77W and south of 27N. Scattered to numerous
showers and thunderstorms are observed south of 28N and between
71W-79W. This activity is shifting westward. The latest ASCAT
data shows an area of fresh to strong east-southeast winds behind
the wave to near 67W. Elsewhere, gentle to moderate anticyclonic
winds are seen north of 20N, and moderate to fresh northeast to
east winds are 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 trade winds 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. The northern part of the Caribbean tropical
wave that extends along 77W will continue to shift westward
toward South Florida during the weekend along with the scattered
to numerous shower and thunderstorm activity.

$$
Aguirre
This weather bulletin was brought to you by:
www.nashvilleweather.net