[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 220000
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
759 PM EDT Tue Aug 21 2018

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 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through
2345 UTC.

...TROPICAL WAVES...

A tropical wave has moved off the African coast with axis along
22W between 06N-20N, moving westward at 10-15 kt. The wave is
embedded within a very dry and stable environment inhibiting
convection at this time.

A central Atlantic tropical wave has its axis extending along 40W
from 05N-18N, moving westward at 10-15 kt. This wave is also
embedded within a very dry and stable environment caused by
Saharan Air Layer outbreak migrating westward across the central
and eastern Atlantic. Only isolated moderate convection is noted
within 60 nm either side of the wave axis along 11N.

A tropical wave has been repositioned based on satellite imagery
and model data. The axis extends now along 60W between 09N-19N,
moving westward near 15-20 kt. No significant convection is
observed with this wave at this time.

A western Caribbean tropical wave has its axis extending along
88W and south of 21N, moving westward at near 15 kt. Scattered
moderate convection is over Central America and Yucatan Peninsula
between 84W-92W.

...MONSOON TROUGH/ITCZ...

The monsoon trough axis extends from coast of Senegal near 14N17W
to 09N23W to 09N43W. No significant convection is noted with these
boundaries at this time.

...DISCUSSION...

GULF OF MEXICO...

Weak ridging reaches across the northern Gulf of Mexico along
roughly 27N, maintaining light to gentle breezes and 1 to 3 ft
seas. Gentle to moderate easterly flow is noted elsewhere south
of the ridge. Latest NWS mosaic radar display shows isolated
showers and thunderstorms across much of the eastern part of the
gulf, mainly due to a weak trough over that area. Scattered
showers and thunderstorms are observed over the far southwest
section of the gulf in association with the Yucatan Peninsula
trough that typically moves offshore across the southwestern gulf
late at night and into the morning hours, with the added factor
of an upper-level low located just east of the coast of Mexico at
22N97W. Expect for this convective activity to remain active
through tonight. Otherwise, high pressure ridging will remain
across the northern gulf waters, with the associated gradient
producing gentle to moderate anticyclonic flow through Thu.

CARIBBEAN SEA...

The pressure gradient across the area will maintain fresh to
strong winds over the south central Caribbean off the coast of
Colombia and across the Gulf of Venezuela through Thu. Moderate
to fresh trades will continue elsewhere through Thu.

The tropical wave along 88W will move across the rest of the
western Caribbean this evening before moving inland Central
America. The tropical wave along 60W will enter the eastern
Caribbean through Wed night and enter the eastern part of the
central Caribbean by Thu.

ATLANTIC OCEAN...

Over the western Atlantic, a surface trough is analyzed from near
30N74W to the central Bahamas. An upper-level trough extends from
an upper-level low at 31N66W to the central Bahamas, and to
central Cuba as a shear axis. Another trough extends from 32N59W
to 27N68W, and another one extends from near 32N45W to 28N50W. A
small surface trough extends from near 31N54W to 28N56W. With
these features in place along with a moist and unstable
environment, the result is scattered shower and thunderstorm
activity over the waters north of 24N between 60W and 75W, with
the most concentrated activity observed north of 27N and
between 70W and 76W. Isolated showers and thunderstorms are
elsewhere west of 58W. A 1025 mb high center is analyzed north of
these troughs at 33N58W, with a ridge extending westward to
Bermuda, and southwestward from there to east-central Florida High
pressure ridging will continue over the basin through the next
several days. The trough extending across the central Bahamas will
continue westward through this evening. The aforementioned shower
and thunderstorm activity is forecast to persist through Wed.

Over the eastern part of the basin, a 1026 mb high is centered
near 34N42W, supporting generally moderate north to northeast
winds north of 20N. Saharan dust and associated dry air, as also
mentioned above under Tropical Waves, is noted mainly east of
about 56W on GOES-16 Saharan Air Layer animation is inhibiting
convection from developing across the eastern and central Atlantic
waters.

For additional information please visit
http://www.hurricanes.gov/marine

$$

JA/ERA
This weather bulletin was brought to you by:
www.nashvilleweather.net