[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151620
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1805 UTC Tue Aug 15 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
1600 UTC.

...TROPICAL WAVES...

The axis of a tropical wave is over west Africa near 13/14W from
04N to 18N, moving W at 10-15 kt. Numerous moderate with isolated
strong convection is occurring from 08N to 16N between 21W and the
west coast of Africa. The tropical wave is forecast to move off
the west coast of Africa tonight or early Wednesday. Some slow
development of this system is possible late this week or over the
weekend while it moves generally WNW or NW across the eastern
Atlantic. There is a low chance for tropical cyclone development
over the next 7 days.

The axis of an Atlantic Ocean tropical wave is near 34W, from 18N
southward, moving W at 15 kt. Scattered moderate convection is
noted from 07N to 13N between 27W and 46W, and from 14.5N to 16.5N
between 32W and 37W. Development, if any, of this system should be
slow to occur while it moves W to WNW at about 15 kt across the
tropical Atlantic through the end of the week. There is a low
chance for tropical cyclone development over the next 7 days.

The axis of an Atlantic Ocean tropical wave is near 57W, from 18N
southward, moving W at 15-20 kt. Scattered moderate convection is
noted from 07N to 12N between 55W and 63W, including over Trinidad
and Tobago.

The axis of a Caribbean Sea tropical wave is near 81W, from 19N
southward through Panama and into the east Pacific, moving W at
15-20 kt. Upper-level diffluence to the east of an upper-level low
centered over Belize and northern Guatemala is enhancing scattered
moderate isolated strong convection across the NW Caribbean from
14N to 22N between 79W and 87W. Numerous moderate isolated strong
convection is also noted over the SW Caribbean south of 12.5N
between 76W and 84W, where the tropical wave intersects the east
Pacific monsoon trough.

...MONSOON TROUGH/ITCZ...

The monsoon trough passes across the coast of Africa near 17N16W
to 13N30W to 12N46W to 09.5N55W. See the Tropical Waves section
above for a description of showers and thunderstorms.

GULF OF MEXICO...

A high pressure ridge stretches across the central Gulf of Mexico
from east to west. Weak surface troughing is over the Bay of
Campeche, where moderate E winds prevail along with 3-4 ft seas.
Light to moderate winds prevail elsewhere with 1-3 ft seas.
Scattered thunderstorms are seen over the NE Gulf from 27N to 30N
and east of 88W. Isolated showers and tstorms are near the coast
of Mexico between Veracruz and Tampico. A surface trough over the
eastern Straits of Florida is spreading scattered tstorms across
the western Straits of Florida and SE Gulf. A narrow upper-level
trough is also producing some cloudiness and isolated showers and
tstorms across the west-central Gulf.

For the forecast, a trough will move off the Yucatan Peninsula
each night into late week, supporting fresh winds off northwest
Yucatan. Elsewhere, a ridge over the Gulf will support mostly
gentle to moderate winds and slight seas across the basin into
Sat.

CARIBBEAN SEA...

See the Tropical Waves section above for a description of showers
and thunderstorms occurring across the basin. No significant
precipitation is noted north of 12N and east of 77W, due to dry
Saharan dust over the eastern two-thirds of the Caribbean, as
noted on the GOES-16 CIMSS Saharan Air Layer Tracking Product.

Recent ASCAT and buoy data show fresh E trade winds across the
eastern and central Caribbean. Recent buoy and altimeter data show
seas of 6 to 7 ft across much of the basin, east of 80W. In the
south-central basin, off the coast of Colombia, ASCAT shows strong
ENE winds from 11N to 12.5N between 74.5W and 77W, where seas of
7 to 8 ft are likely occurring. Moderate or weaker winds and 2 to
5 ft seas prevail across the western Caribbean.

For the forecast, ridging over the western Atlantic will support
fresh to locally strong winds across mainly the south-central
Caribbean through Wed. Moderate winds and seas will persist
elsewhere.

ATLANTIC OCEAN...

A surface trough is moving westward over the eastern Straits of
Florida, from 26.5N79.5W to 23N81W. Scattered thunderstorms are
noted from 23N to 26N, and west of 77W through the Straits of
Florida. Scattered moderate convection is also noted offshore NE
Florida, north of 28N between 77.5W and 80.5W. An upper-level low
centered near 26N66W is only able to induce isolated showers and
tstorms from 25.5N to 27.5N between 65W and 66.5W as a large plume
of dry Saharan dust has recently caught up with the upper-low.
Surface ridging dominates the remainder of the basin, anchored by
a 1025 mb high pressure center near 35N41W. A surface ridge axis
extends WSW from that high to the NW Bahamas. Recent ASCAT
satellite data shows moderate to fresh NE to E trade winds from
15N to 26N between 35W and 60W, where seas are 6 to 8 ft,
confirmed by recent satellite altimeter passes. The data also
shows moderate to fresh ESE trades north of Hispaniola through the
SE Bahamas and in the Windward Passage, where seas are likely 4
to 5 ft. Gentle to moderate wind speeds are farther north, closer
to the ridge axis. Over the far NE Atlantic, from the Canary
Islands to the coast of Western Sahara, fresh to strong NE winds
and seas of 7 to 9 ft prevail. Of note, a dry airmass due to
Saharan dust covers much of the basin from 13N to 27N, and east of
70W.

For the forecast W of 55W, fresh to locally strong winds will
pulse north of Hispaniola late this afternoon and early evening.
Gentle to moderate winds will prevail elsewhere, freshening S of
25N starting Thu.

$$
Hagen
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