[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172328
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...SPECIAL FEATURES...

Eastern Tropical Atlantic (AL98):
A broad area of low pressure, centered near 15N28W at 1009 mb, is
partially associated with a tropical wave that has an axis along
29W/30W from 07N to 19N. It is moving WNW, and is producing a
broad area of disorganized scattered moderate convection from 10N
to 17N between 24W-31W. This activity is located 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 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 medium chance of tropical cyclone development
within 48 hours.

Central Tropical Atlantic (AL99):
A 1008 mb low pressure is centered near 12N40W. This low is part
of an elongated trough of low pressure that is located about 870
nm west-southwest of the Cabo Verde Islands. Scattered moderate
to isolated strong convection is seen 10N to 13N between 40W-42W.
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-northwest across the
central tropical Atlantic. 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 both special features.

...TROPICAL WAVES...

Please see Special Features section above for information on a
tropical wave along 29W/30W that has induced low pressure
formation and that has a potential for tropical development and
on a central Atlantic area of low pressure with a low near
12N40W.

A central Atlantic tropical wave has its axis near 49W from 07N
to 19N. It is moving westward near 15 kt. Scattered moderate and
isolated strong convection is noted from 10N to 14N between 45W
and the wave.

A Caribbean tropical wave has its axis near 71W, or from the
western part of the Dominican Republic to just inland Colombia.
It is moving westward around 13 kt. The wave has helped to set
off scattered to numerous moderate convection over most of
Hispaniola as it works on diurnal and local effects that already
include abundant available moisture there. Expect for this
activity to remain quite active into tonight. Scattered showers
and isolated thunderstorms are near the west section of Puerto
Rico.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis enters the Atlantic through the coast of
Mauritania that borders Senegal 17N17W and continues to 15N22W
to low pressure near 15N28W to 12N34W, to low pressure near
12N40W, to 11N45W and to 11N54W. Outside of convection associated
to the Special Features and tropical waves, scattered moderate
to isolated strong convection is within 120 nm north of the
trough between 31W-35W, and also from 08N to 11N between 51W-54W.

GULF OF MEXICO...

A weak stationary front resides along the northern Gulf coast,
where scattered moderate convection is occurring. Otherwise, high
pressure prevails across the Gulf waters, with a weak pressure
gradient supporting light to gentle winds and seas of 1 to 3 ft.

For the forecast, the present high pressure over the area
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 western 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...

The pressure gradient between the subtropical ridge in the
central Atlantic and low pressure over NW Colombia is supporting
fresh to locally strong easterly trade winds in the south central
Caribbean. Moderate to locally fresh winds are over the north
central and eastern Caribbean. Gentle to moderate winds are in
the western Caribbean. Seas are in the 5-7 ft range in the
central Caribbean, with 4-6 ft seas elsewhere, except for lower
seas of 2-4 ft seas in the NW basin.

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
northeast Caribbean Sat night into Mon.

ATLANTIC OCEAN...

See Special Features section above for details on two low
pressure systems in the central and eastern Atlantic that could
become tropical cyclones.

An expansive subtropical ridge dominates the tropical and
subtropical Atlantic waters N of 20N. Fresh to locally strong
winds, and seas of 7-9 ft, are noted from 16N to 24N between 35W
and 70W. Gentle to moderate winds, and seas of 4-6 ft are noted
elsewhere. The exception is a zone of fresh southerly winds
north of the Bahamas, ahead of a stationary front that extends
from the southeastern U.S. to just along the coast of Louisiana
and northwestward from there to eastern Texas, where it
transitions to a warm front. A surface trough is north of the
Bahamas along 78W from 27N to 30N. An area of scattered showers
and thunderstorms is south of 25N between 67W-75W, and also
north of 25N west of 74W.

For the forecast W of 55W, fresh to locally strong trade winds
will pulse off Hispaniola each evening through the weekend. Fresh
tradewinds south of 25N today will persist through Sat. Fresh to
locally strong SW winds east of northern Florida will diminish
late tonight. 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.

$$
Aguirre
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