Tropical Weather Discussion
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AXNT20 KNHC 120511

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
110 AM EDT Sat Aug 12 2017

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 0000 UTC surface analysis and satellite imagery through
0500 UTC.


A 1013 mb low is centered near 22N67W. Scattered moderate
convection is noted from 20N-25N between 64W-68W. Dry air aloft
and unfavorable upper-level winds have limited significant
development during the past few days. Environmental conditions,
however, are expected to become a little more conducive for
development during the next day or two, and this system could
become a tropical depression over the weekend. The low is forecast
to move generally northwestward through the weekend and is likely
to turn northeastward away from the United States early next
week. There is a medium chance for tropical cyclone formation
during the next 48 hours.


The axis of a tropical wave in the far eastern Atlantic is near
21W from 08N to 20N, moving W at 15-20 kt. Scattered moderate
convection is noted within 120 nm west of the wave axis from 07N-

The axis of a tropical wave in the central Atlantic is near 42W
from 05N to 19N, moving W at 15-20 kt. Scattered showers are
within 180 nm west of the wave axis south of 10N.

The axis of a tropical wave in the central Caribbean is near 75W
from 05N to 20N. Scattered moderate to isolated strong convection
is noted over the western half of Hispaniola. Scattered showers
are elsewhere within 90 nm of the wave axis south of 11N.


The monsoon trough extends from the African coast near 14N17W to
10N26W to 11N33W to 07.5N46W. The Intertropical Convergence Zone
continues from 07.5N46W to the South American coast near 07N58W.
Aside from convection associated with the tropical waves,
scattered moderate convection is noted from 06N-12N between 25W-



A 1020 mb high is centered over the NE Gulf of Mexico near 27N88W.
A thermal trough has developed over the Yucatan Peninsula earlier
this evening and is moving into the southwest Gulf waters.
Scattered convection is noted over the southwest Gulf west of the
trough axis. Light to gentle anticyclonic flow is noted over the
Gulf waters, with the exception of moderate winds noted west of
the thermal trough moving off the Yucatan into the southwest Gulf.
High pressure will continue to remain centered over the Gulf
waters this weekend, with associated anticyclonic flow continuing.
A thermal trough will develop each evening over the Yucatan
Peninsula, shifting westward into the southwest Gulf during the
overnight hours, and dissipating over this area each morning.
Locally higher winds can be expected west of the trough axis.


A tropical wave is moving through the central Caribbean. See
Tropical Waves section for details. The tropical wave will
continue to propagate westward, moving west of the area late
Sunday night. Fresh to locally strong winds prevail over the
south central Caribbean, while gentle to moderate winds prevail
elsewhere. These general conditions will prevail through the


Active convection continues across the western half of Hispaniola,
enhanced by a tropical wave moving across the area. The wave will
move further from the area over the weekend. However, expect
diurnal convection to flare up each afternoon over the weekend.


Please see the tropical wave section above for more on the
tropical waves moving across the Atlantic waters. Also, please see
above in the special features section for more on low pressure,
and the potential for tropical cyclogenesis, over the southwest
north Atlantic waters. Winds are generally in the light to
moderate range over the Atlantic waters, with the exception of
strong winds prevailing in the vicinity of the low pressure center
mentioned above. The subtropical high will strengthen over the
central Atlantic this weekend. The pressure gradient will tighten
between the area of high pressure and the tropical wave currently
over the eastern Atlantic this weekend. This will freshen winds
north of the tropical wave by Sunday as the wave propagates

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