AXNT20 KNHC 241156
Tropical Weather Discussion
NWS National Hurricane Center Miami FL
805 AM EDT WED AUG 24 2016
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 0600 UTC surface analysis and satellite imagery through
Tropical Storm Gaston is centered near 14.9N 38.6W at 24/0900
UTC or about 850 nm west of the Cabo Verde Islands moving west-
northwest at 15 kt. Estimated minimum central pressure is 999
mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt.
Scattered moderate to isolated strong convection is from 13N-17N
between 35W-40W. Clusters of scattered moderate convection are
from 15N-20N between 39W-43W. Please see the latest NHC
Intermediate Public Advisory under AWIPS/WMO headers
MIATCPAT2/WTNT32 KNHC and the full Forecast/Advisory under the
AWIPS/WMO headers MIATCPAT2/WTNT22 KNHC for more details.
A tropical wave moving across the Lesser Antilles is analyzed
from 21N66W along 18N63W through a 1009 mb low near 17N61W to
12N59W. This system could become a tropical depression during
the next day or two as it moves west-northwest 13 to 17 kt.
Conditions could become more conducive later this week while the
system moves near the southeastern and central Bahamas.
Scattered moderate to isolated strong convection is from 15N-18N
between 60W-64W. Scattered showers and possible isolated
thunderstorms are from 17N-21N between 56W-67W. There is a
medium chance of tropical formation in the next 48 hours.
Interests from the islands of the northeastern Caribbean Sea to
the Bahamas should continue to monitor the progress of this
system. Gusty winds, heavy rains, and possible flash floods and
mud slides could occur over portions of these areas regardless
of tropical cyclone formation.
The monsoon trough extends across Africa into the east Tropical
Atlantic near 18N16W and continues along 14N21W to 14N27W. The
ITCZ begins near 6N44W and continues along 5N49W to South
America near 6N58W. The monsoon trough/ITCZ continues to be
disrupted by Tropical Storm Gaston. Clusters of scattered
moderate to isolated strong convection are from 5N-10N east of
17W to inland over west Africa.
GULF OF MEXICO...
A broad upper ridge is anchored over the central Mississippi
covering the Gulf waters north of 26N. An elongated upper trough
is centered in the northwest Caribbean and extends an upper
trough across the Yucatan peninsula to the coast of Mexico near
23N98W generating scattered showers and isolated thunderstorms
in the southwest Gulf south of 21N between 93W-97W. A surface
trough is in the east Gulf extending from 29N85W to 25N83W
generating scattered showers and isolated thunderstorms within
120/150 nm west of the surface trough. Similar showers and
thunderstorms are within 45 nm either side of the Florida Keys.
A surface ridge extends from over the southeast CONUS to over
the Gulf anchored by a 1026 mb high in the northwest Atlantic.
This surface ridge will shift north of the Gulf later today
with the pressure gradient tightening across the northeast
Gulf waters briefly tonight.
The primary concern this morning is the tropical wave/low moving
through the Lesser Antilles. Please see the Special Features
section above for the activity associated with this system over
the east Caribbean. An elongated upper low is centered in the
northwest Caribbean near 17N85W and extends an upper trough
northwest across the Yucatan peninsula into the Gulf of Mexico
and southeast to the Gulf of Uraba. Clusters of scattered
showers and isolated thunderstorms are within 90 nm of a line
from 17N73W to the Yucatan Channel near 22N86W and in the
southwest Caribbean south of 12N between Colombia and Costa
Rica. This is leaving the remainder of the basin with fair
weather this morning. Fresh trade winds will develop across the
east and central Caribbean tonight and continue through
Saturday. Strong northeast winds are expected along the
northwest coast of Colombia tonight. The Special Features low
and tropical wave will track northwest through the Bahama chain
before reaching the northwest Bahamas late in the weekend.
Currently showers and thunderstorms are over the southwest
peninsula of Haiti. Showers and thunderstorms associated with
the tropical wave and low moving through the Lesser Antilles,
see Special Features above, are approaching the eastern portion
of the Dominican Republic this morning and spread westward
throughout the day. The low is expected to be north of the Mona
Passage late tonight then northwest of Haiti by late Thursday
night, but could still produce gusty winds, heavy rains, and
possible flash floods and mud slides over portions of the
The primary concern for the central Atlantic this morning is
Tropical Storm Gaston and the possible development of the low
and tropical wave in the Special Features section above. The
upper ridge over the Gulf of Mexico extends a ridge axis across
south Georgia/northeast Florida and into the west Atlantic to
29N75W. The upper trough over the south Gulf of Mexico extends a
trough axis from the Straits of Florida across the Bahamas to
26N74W. This is creating a diffluent environment to generate
scattered showers and isolated thunderstorms from 23N-30N west
of 75W. An upper trough north of 30N is supporting a stationary
front that extends through 32N66W to 30N72W with scattered
showers and isolated thunderstorms within 60 nm either side of
the front and continues to 29N75W. A 1016 mb low, the remnants
of Fiona, is centered near 27N66W and coupled with diffluent
flow from a second upper ridge is generating scattered showers
and isolated thunderstorms within 75 nm of a line from 27N69W to
beyond 32N62W. An upper low is over the central Atlantic near
27N50W is supporting a surface trough that extends from 30N47W
to 25N49W and is generating scattered showers and possible
isolated thunderstorms from 25N-31N between 44W-50W. The
remainder of the basin east of 60W is dominated by a surface
ridge anchored by a 1026 mb high near the Azores and a 1024 mb
high near 34N48W. The Special Features low and tropical wave
will track northwest through the Bahama chain before reaching
the northwest Bahamas late in the weekend. Tropical Storm Gaston
is expected to remain east of 60W as it tracks northwest
before turning northward late in the weekend.
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