[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231200
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1205 UTC Sun Jul 23 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 0600 UTC surface analysis and satellite imagery through
1145 UTC.

...SPECIAL FEATURES...

Recently downgraded Tropical Storm Don is centered near 42.6N
48.9W at 23/0900 UTC, or about 300 nm SE of Cape Race Newfoundland
moving NNE at 14 kt. Estimated minimum central pressure is 993
mb. Maximum sustained wind speed has diminished to 55 kt with
gusts to 65 kt. Seas near the center are up to 30 ft. Satellite
imagery shows that Don's eyewall convection has become fragmented.
Scattered to numerous moderate convection is confined to within
90 nm of the center in the eastern semicircle, and from 44N to
46N between 47W-49W where the convection is embedded within
moderate to heavy rain patches. Small clusters of showers and
thunderstorms denote an outer rainband are within 30 nm of line
from 42N52W to 41N51W and also within 30 nm of 41N48W. Don is
forecast to turn northeastward later today and east-northeastward
on Mon. Further weakening is forecast, and Don is likely to lose
tropical characteristics by early on Mon.

Please read the latest HIGH SEAS FORECAST issued by National
Hurricane Center at website
https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest T.S.
Don Forecast/Advisory and Public Advisory at www.hurricanes.gov
for more details.

...TROPICAL WAVES...

An eastern Atlantic tropical wave has its axis along 23W from
04N to 19N. It is moving westward at 10-15 kt. Scattered moderate
convection is seen from 05N to 12N and between 16W-27W. Dry air to
the north of the wave is inhibiting convection from forming there.

A central Atlantic tropical wave has its axis along 36W/37W from
05N to 19N, moving westward at 10-15 kt. Scattered moderate
convection is ahead of this wave from 03N to 06N between the
wave and 46W. Isolated showers and thunderstorms are east of the
wave axis to 30W and from 04N to 07N.

A western Caribbean tropical wave has its axis along 86W and
south of 19N. It is moving westward at 10-15 kt. The interaction
between the wave axis and the eastern Pacific monsoon trough is
producing scattered showers and a few thunderstorms south of 14N
and west of 80W to the coast of Panama.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis enters the Atlantic through the coast of
Mauritania near 20N16W and continues southwestward to 12N22W and
to 11N30W to 11N39W to low pressure (Invest 95L) near 11N45W 1012
mb and to 12N51W. In addition to convection associated to the
tropical waves as described above, scattered moderate to isolated
strong convection is within 60 nm south of the trough between
46W-50W and from 12N to 15N between 45W-50W.

...GULF OF MEXICO...

A stationary front is draped across the southern United States.
Earlier it was enhancing the shower and thunderstorm activity
across the northern Gulf coast. This activity is forecast to
re-develop today. Isolated showers and thunderstorms are over
northern Gulf of Mexico waters east of 92W. Farther south,
scattered showers and isolated thunderstorms are seen in the
eastern Bay of Campeche. The remainder of the Gulf remains under
the western periphery of the subtropical ridge positioned near
the Azores. Moderate or weaker winds and seas of 1-3 ft are
prevalent across the basin.

For the forecast, weak high pressure over the area will change
little into the early part of the week. This will support mainly
gentle to moderate winds, except over the eastern Bay of Campeche
where winds will be enhanced by a thermal trough that will emerge
off the Yucatan Peninsula daily during the overnight hours.

...CARIBBEAN SEA...

Please see the Tropical Wave section above for details on ongoing
convection that is the southwestern Caribbean Sea.

The remainder of the basin is under the influence of a
subtropical ridge positioned near the Azores. Saharan dust covers
most of the Caribbean, resulting in drier conditions, above
normal temperatures and reduced visibility.

The pressure gradient between the aforementioned ridge and lower
pressures in northern South America continues to support fresh to
strong easterly trade winds in the central Caribbean and the Gulf
of Honduras. The strongest winds are occurring off northern
Colombia. Over the rest of the Caribbean, moderate or weaker winds
prevail. Seas are 7-10 ft over the central Caribbean and the Gulf
of Honduras and mostly 4-6 ft elsewhere.

For the forecast, the pressure gradient between the Bermuda High
and lower pressure in Central America and northern South America
will maintain strong trades across the central Caribbean into Sun.
Winds should diminish slightly to fresh to strong tonight through
Wed. Fresh to locally strong trades will develop over the Gulf of
Honduras this evening and diminish Mon afternoon. These winds
develop again Mon evening and diminish early Tue. Low pressure
over the tropical N Atlantic well east of the forecast waters is
expected to weaken to a trough during the early part of the week
as it approaches the Lesser Antilles. Some increase in winds and
seas may accompany the trough.

...ATLANTIC OCEAN...

Please see the Special Features section for information on
recently downgraded Tropical Storm Don in the north-central
Atlantic.

A 1012 mb low pressure system, designated as Invest 95L, is
located near 11N45W. Satellite imagery shows increasing scattered
to numerous moderate convection from 10N to 15N between 46W-50W.
Fresh to locally strong northeast to east winds are north of the
low to near 19N and between 40W-48W. Seas with these winds are 6-8
ft. Although environmental conditions are only forecast to be
marginally conducive for some gradual development, this system
could still become a tropical depression during the next few days
while it moves westward across the tropical Atlantic and eastern
Caribbean Sea. Unfavorable upper-level winds are forecast when
the system moves into the central Caribbean around midweek,
decreasing the chances of formation. Interests in the Lesser
Antilles should monitor the progress of this system. The
disturbance has a low chance of development over the next 48
hours. Refer to the latest Tropical Weather Outlook at
www.hurricanes.gov for more details.

Scattered moderate convection is occurring from 26N to 30N between
66W-70W. Farther west, an outflow boundary is moving south off
central Florida and near the NW Bahamas. It has generated
scattered showers and isolated thunderstorms within 30 nm of
line from 27N78W to 27N74W. The rest of the western Atlantic
(west of 55W) remains under the western periphery of the
subtropical ridge positioned near the Azores. Moderate or weaker
winds and generally seas of 3-5 ft continue to the west of 55W.

Over the remainder of the tropical Atlantic, the pattern is
dominated by a 1031 mb high pressure near the Azores. The strong
pressure gradient between the aforementioned ridge and lower
pressures in NW Africa supports fresh to near gale-force northerly
winds in the eastern Atlantic, mainly north of 19N and east of
35W. This was confirmed by an overnight ASCAT data satellite pass.
The strongest winds are noted north of 25N and east of 22W. Seas
in the affected area are 6-9 ft. Moderate or weaker winds and
slight to moderate seas are present over the remainder of the
tropical Atlantic.

For the forecast west of 55W, weak high pressure over the area
will change little during the next few days. Fresh trades may
pulse nightly N just N of Hispaniola and over the Windward Passage
starting tonight. Elsewhere across forecast waters, winds will be
moderate or weaker over most of the western half of the area and
mostly at moderate to fresh speeds elsewhere.

$$
Aguirre
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