Tropical Weather Discussion
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AXNT20 KNHC 201744

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
144 PM EDT Sun Aug 20 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 1200 UTC surface analysis and satellite imagery through
1615 UTC.

A tropical wave extends from 11N76W to 20N75W moving W at 15-20
kt. The remnant circulation of Harvey continues to be analyzed as
a 1006 mb low along the wave axis near 15N75W with scattered to
numerous moderate and scattered strong convection occurring from
12N-17N between 73W-80W. Regardless of development...the wave
will enter the SW Caribbean Sea waters tonight into early Monday
and approach Central America late Monday morning into the
afternoon hours. Largest impacts at this point will be the
expected rainfall and strong convection the wave and low pressure
area will generate across interior portions of Nicaragua and
Honduras on Monday shifting westward to Guatemala...Belize...
southern Mexico...and the Yucatan peninsula Monday night into
Tuesday. In addition to the expected rainfall...a higher
probability of flash flooding and mudslides will be an ongoing
hazard across this region early in the week.

A tropical wave extends from 09N52W to 17N50W moving W at 15-20
kt. The wave coincides with 700 mb troughing between 46W-53W...and
a maximum in 850 mb relative vorticity in the vicinity of a
fractured portion of energy N of the wave axis analyzed as a
surface trough from 18N49W to 24N47W. The fractured energy is
largely due to an upper level low centered to the NW of the wave
centered over the central Atlc near 26N53W. No significant deep
convection is associated with the wave itself...however scattered
moderate convection is occurring in the vicinity of the surface
trough from 19N-25N between 45W-49W.

A tropical wave extends from 09N66W to 18N66W moving W at 15-20
kt. The wave coincides with weak 850 mb relative vorticity noted
in global model data in the vicinity of the wave between 65W-71W.
A fractured portion of energy N of the wave axis is analyzed as a
surface trough from 19N67W to 27N66W and remains the focus for
most of the ongoing convection. Scattered moderate convection is
from 19N-26N between 63W-69W.

A tropical wave extends from 10N87W to 20N86W moving W at 15-20
kt. Subtle troughing at 700 mb is noted in global model data over
the NW Caribbean Sea and portions of Central America. Isolated
moderate convection is from 16N-20N between 83W-89W.

The monsoon trough extends from the African coast near 14N17W to
10N25W to 07N35W. Widely scattered moderate convection is from
08N-15N between 16W-23W...and from 03N-07N between 27W-41W.


An upper level low is centered over the eastern Gulf near 24N86W
and continues to provide support for a surface trough analyzed
across the adjacent coastal waters of the Florida peninsula and
southern portions of the peninsula from 29N80W to 24N82W. Low-
level moisture convergence along with divergence aloft is
generating scattered showers and tstms generally N of 23N between
80W-86W. Farther west...a surface ridge anchored by a 1016 mb
high centered near 28N93W extends an axis S-SW across the western
Gulf to 20N97W. A few isolated showers and tstms are occurring
across the central waters from 22N-26N between 89W-93W...however
elsewhere skies remain mostly cloudy within light to gentle
easterly winds. With the surface ridge axis extending east-west
along 30N/31N...gentle to moderate E-SE winds are expected through

Three tropical waves continue moving across the basin this
afternoon and are highlighted above. One of these waves is the
special feature wave containing the remnants of Harvey. Scattered
to numerous showers and scatterer strong tstms are occurring
across the area from 12N-17N between 73W-80W. This wave will reach
Central America by late Monday morning into the afternoon hours.
Elsewhere...Scattered showers and tstms are occurring across
Puerto Rico and the adjacent coastal waters N of 16N between 63W-
67W...and across the SE Caribbean S of 12N between 59W-64W.

Daytime heating...local sea breezes...and mountain upslope
lifting will combine with available moisture and produce
scattered showers and thunderstorms across the island mainly
during the afternoon and evening hours this afternoon. An
approaching tropical wave currently along 67W will bring increased
moisture...cloudiness...and precipitation to the island on Monday.

The SW North Atlc remains under the influence of an upper level
low centered over the eastern Gulf of Mexico near 24N86W and the
associated surface trough extending from the Florida Keys N-NE to
29N80W. Scattered showers and tstms are occurring from 24N-31N
between 77W-82W. Otherwise...the remainder of the SW North
Atlc...outside of the surface trough along 67W mentioned in the
tropical wave section falls within the influence of a surface
ridge anchored by 1021 mb high centered near 31N67W. Elsewhere...
outside of tropical wave in the vicinity of 50W...surface ridging
prevails across the central and eastern Atlc anchored by a 1025
mb high centered near 31N42W.

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