[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120537
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
0605 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 0000 UTC surface analysis and satellite imagery through
0500 UTC.

...TROPICAL WAVES...

An central Atlantic tropical wave was relocated based on wave
diagnostic and satellite imagery, and its axis is now along 34W,
south of 15N. Isolated to scattered moderate convection is
observed near mainly west of the wave axis from 06N to 10N.

A vigorous and well defined tropical wave is crossing the Lesser
Antilles. The wave axis extends from 21N59W 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 15N to 20N and between 59W and 67W, also affecting the
northern Lesser Antilles. Resent wind data from ASCAT shows
fresh to strong E-SE winds, mainly north of 16N. Near the
strongest convection, gale- force gusts may be possible. Seas of 6
to 9 ft are within these winds. This tropical wave will approach
the U.S./UK Virgin Islands and Puerto Rico later today as its
moves across the eastern Caribbean.

A western Caribbean Sea tropical wave has its axis along 83W,
south of 21N, moving westward at 10-15 kt. This wave extends from
the Cayman Islands to eastern Costa Rica. Isolated convection is
noted west of the wave axis off the coast of Nicaragua.

...MONSOON TROUGH/ITCZ...

The monsoon trough enters the Atlantic through the coast of
Bissau near 21N16W and continues southwestward to 12N24W. The
ITCZ extends from 12N24W to 09N33W. It resumes at 09N35W to
06N51W. Scattered moderate convection is noted from 05N to 09N
between 41W and 51W.

GULF OF MEXICO...

A pre-frontal trough along the northern Gulf coast and divergence
aloft results in scattered showers and isolated thunderstorms
affecting the north-central Gulf waters, near the coast of New
Orleans and Alabama. Another area of scattered to isolated strong
convection is noted along the Yucatan Peninsula in association
with a surface trough. The rest of the basin is in the western
periphery of the subtropical ridge positioned near 27N52W,
maintaining fairly tranquil weather conditions. Outside of
convection, 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.

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

CARIBBEAN SEA...

Aside from the convection described in the TROPICAL WAVES
section above, a fairly dry weather pattern continues to dominate
the remainder of the Caribbean Sea, suppressing the development
of deep convection as some patches of Saharan dust continue to
linger around the basin. 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. Light to gentle winds and slight seas prevail in the
rest of the Caribbean.

For the forecast, a tropical wave moving into the eastern
Caribbean will move across the central Caribbean through Thu and
the western Caribbean through Sun. Another tropical wave will move
across the Windward Islands Fri, across the southeast Caribbean
Sat and into the south-central Caribbean Sun. The passage of the
tropical waves will modulate fresh to strong winds across mainly
the central Caribbean through the period.

ATLANTIC OCEAN...

The subtropical ridge located in the central Atlantic near 27N52W
continues to dominate the tropical Atlantic sensible weather.
Aside from a few showers and isolated thunderstorms off Florida
coast and well SE of Bermuda near 39N, 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. For convection
in the deep tropics, please refer to the TROPICAL WAVES and
MONSOON TROUGH/ITCZ sections above.

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 51W. Seas in these waters are 4-8 ft. Moderate
to locally strong northeasterly to 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 northeasterly winds are affecting the waters S of
30N and east of 26W. These winds are supporting seas of 5-9 ft.
Moderate northeasterly winds are present south of 28N 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, high pressure will persist northeast
of the Bahamas through Sun. A weak frontal boundary will stall
between northeast Florida and Bermuda through Thu, and dissipate
Fri. Farther south, the northern end of a tropical wave will move
westward across the waters south of 22N through Fri. Expect fresh
to strong NE to E winds and rough seas south of 22N both ahead of
and following the tropical wave.

$$ KRV
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