[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112307
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0005 UTC Wed Jul 12 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
2230 UTC.

...TROPICAL WAVES...

An eastern Atlantic tropical wave has its axis along 28W, south
of 15N, moving westward at 10-15 kt. Isolated moderate convection
is observed near the wave axis from 05N to 08N.

An active and well defined tropical wave is nearing the Lesser
Antilles. The wave axis extends from 21N58W to the coast of
northeast Venezuela. This wave is moving westward at 20-25 kt.
Divergence aloft due to an upper level trough is enhancing the
development of numerous moderate to isolated strong convection
from 13N to 20N and between 56W and 67W, also affecting the
Lesser Antilles. Latest satellite-derived wind data show fresh to
strong E-SE winds, mainly north of 14N. Near gale-force gusts are
possible in association with the strongest convection. Seas of 6
to 9 ft are within these winds. The rain activity and breezy
conditions will progress westward over the next few days,
affecting the Virgin Islands, Puerto Rico and Hispaniola midweek
and Cuba and the Bahamas late in the week.

A western Caribbean Sea tropical wave has its axis along 82W,
south of 21N, moving westward at 10-15 kt. This wave extends from
the Cayman Islands to western Panama. Interaction between the wave
axis and the eastern Pacific monsoon trough in the SW Caribbean
Sea is producing numerous moderate to isolated strong convection
south of 17N and between NW Colombia and SE Nicaragua.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic through the coast of
Mauritania near 21N16W and continues southwestward to 06N47W. The
ITCZ extends from 06N47W to 08N53W. Scattered moderate convection
is noted from 06N to 11N and east of 21W. Similar convection is
evident from 04N to 11N and between 16W and 56W.

GULF OF MEXICO...

A pre-frontal trough along the northern Gulf coast and divergence
aloft result in scattered showers and isolated thunderstorms
affecting the NE Gulf waters, especially north of 26N. The rest
of the basin is in the western periphery of the subtropical ridge
positioned near 27N42W, maintaining fairly tranquil weather
conditions. The weak pressure pattern support light to locally
moderate anticyclonic winds and seas of 2-4 ft, with the highest
seas occurring in the central Bay of Campeche. Stronger winds are
likely found with the strongest convection in the NE Gulf.

For the forecast, a ridge will continue to dominate the Gulf
waters while a trough will develop over the Yucatan Peninsula each
evening and move offshore. Under this weather pattern, moderate
to fresh winds will pulse north and west of the Yucatan peninsula
during the late afternoon and evening hours. Elsewhere, gentle to
moderate anticyclonic flow and slight seas will prevail.

CARIBBEAN SEA...

Aside from the convection described in the TROPICAL WAVES
section, a fairly dry weather pattern continues to dominate the
remainder of the Caribbean Sea, suppressing the development of
deep convection. A recent scatterometer satellite pass captured
fresh to strong easterly trade winds in the central and SW Caribbean.
Seas in these waters are 7-10 ft. Moderate to fresh easterly
breezes and seas of 3-7 ft are noted in the eastern Caribbean and
the Gulf of Honduras. There are some locally strong winds in the
southern Gulf of Honduras. Light to gentle winds and slight seas
prevail in the rest of the Caribbean.

For the forecast, fresh to strong winds and rough seas will
continue over the central Caribbean through the weekend. Strong to
near gale force winds are likely off Colombia and in the Gulf of
Venezuela mainly at night. Fresh to strong winds are expected in
the Gulf of Honduras tonight, then mainly moderate to fresh winds
will prevail the remainder of the forecast period. Moderate to
fresh trade winds and moderate seas will prevail over the E
Caribbean and the tropical Atlantic waters through Sun night. A
tropical wave, currently located along 60W, will bring an increase
in winds and seas across the waters just E of the Leeward Islands
today, and over the NE Caribbean tonight into on Wed. Fresh to
strong NE winds are expected in the Windward Passage ahead of the
wave axis by Wed night.

ATLANTIC OCEAN...

The subtropical ridge located in the central Atlantic near 27N48W
continues to dominate the tropical Atlantic. Aside from a few
showers and isolated thunderstorms off Florida coast and well SE
of Bermuda near 30N, generally dry weather conditions prevail
across the forecast waters, outside of the deep tropics. The dry
conditions are supported by a Saharan airmass that covers most of
the tropical Atlantic, especially in the central and eastern
Atlantic. The dust particles in the atmosphere are also reducing
the visibility, particularly in the eastern Atlantic, where the
Saharan airmass is the densest.

The pressure gradient between the ridge and lower pressures north
of the SW Atlantic result in moderate to fresh SW-W winds north
of 28N and west of 55W. Seas in these waters are 4-8 ft. Moderate
to locally strong easterly winds are found south of 23N and west
of 50W, along with seas of 5-8 ft. Elsewhere west of 55W, light
to gentle winds and slight seas are prevalent. Fresh to strong
northerly winds are affecting the waters S of 22N and east of
23W. These winds are supporting seas of 5-8 ft. Moderate easterly
winds are present south of 22N and between 25W and 55W, along with
moderate seas. In the remainder of the basin, moderate or weaker
winds and slight to moderate seas prevail.

For the forecast W of 55W, a ridge will remain in place across
the forecast waters while weakening some by Wed as a developing
low pressure moves SE and crosses near the NE waters. Fresh W to
NW winds and seas to 8 ft, in association with the low, are
expected to impact the NE waters tonight into Wed. The northern
end of a tropical wave is forecast to affect the waters north of
the Leeward Islands and Puerto Rico on Wed, and north of
Hispaniola, including approaches to the Windward Passage by Wed
night. In addition, an area of fresh to locally strong E winds are
expected off Hispaniola over the next several days. Light to
gentle winds will persist along the ridge axis.

$$
AReinhart
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