AXNT20 KNHC 241744

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
144 PM 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 1200 UTC surface analysis and satellite imagery through
1730 UTC.


Tropical Storm Gaston is centered near 16.1N 39.4W at 24/1500 UTC
or about 886 nm west of the Cabo Verde Islands moving northwest
at 14 kt. Estimated minimum central pressure is 999 mb. Maximum
sustained wind speed is 60 kt with gusts to 75 kt. Scattered
moderate convection is from 14N-19N between 36W-44W. 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 with axis
extending from 21N66W to a 1009 mb low near 18N63W to 12N61W.
At this time, scattered moderate convection is observed from
15N-21N between 61W-68W. As of 25/1500 UTC; an Air Force
Reconnaissance aircraft and latest scatterometer data reported
gale force winds from 17N-20N between 61W-65W in association to
this system. Although environmental conditions are currently
marginally conducive for additional development, this system could
become a tropical depression or tropical storm at any time during
the next few days while it moves west-northwestward at about 10-15
kt across the northern Leeward Islands, Puerto Rico, Hispaniola,
and the Bahamas. Strong winds, heavy rains, and flash floods and
mudslides are possible across these islands. This system has a
medium chance of tropical formation through the next 48 hours.


See above.


The Monsoon Trough extends across Africa into the east Tropical
Atlantic near 18N16W and continues to 08N27W. The ITCZ begins
near 09N43W and continues to 06N57W. Clusters of moderate convection
are south of the Monsoon Trough mainly south of 10N east of 20W.



A surface ridge prevails across the basin anchored by a 1020 mb
high centered near 28N93W. To the east of this feature; a surface
trough extends from 30N86W to 26N88W with isolated moderate
convection. Another surface trough extends over the southeast Gulf
waters and the southern portion of the Florida Peninsula from
25N83W to 26N80W. Scattered moderate convection is observed along
this boundary. Scatterometer data and surface observations depict
a gentle to moderate anticyclonic flow across the basin. Expect
during the next 24 hours for the surface ridge to shift northward.
Convection will continue across the southeast waters.


The primary concern this morning is the tropical wave/low moving
through the Lesser Antilles. Please see the Special Features
section above for more information. An elongated upper-level low
is centered in the western Caribbean near 18N85W. This feature is
supporting isolated moderate convection mainly west of 78W. To the
south; the Monsoon Trough extends north of Panama along 10N supporting
scattered moderate convection between 76W-83W. Scatterometer data
depicts moderate to fresh trades across most of the area except
south of 13N between 73W-78W where fresh to strong winds prevail.
As of 25/1500 UTC; an Air Force Reconnaissance aircraft and latest
scatterometer data reported gale force winds north of 17N and east
of 64W in association to the tropical wave/low pressure in the
eastern Caribbean. Expect through the next 24 hours for the
surface low to continue moving west-northwest with convection and
gusty winds. Little change is expected elsewhere.


Showers and thunderstorms associated with the tropical wave and
low in the Lesser Antilles are approaching the island at this
time. Expect weather conditions to deteriorate as these features
continue moving west. The low is expected to be north of the Mona
Passage late tonight then northwest of Haiti by late Thursday
night. Gusty winds, heavy rains, and flash floods and mud slides
are possible across the island.


The areas of concern across the basin are the east-central
Atlantic due to Tropical Storm Gaston and the possible
development of the low and tropical wave currently moving across
the Lesser Antilles. Please see the Special Features section
above for details. A surface trough extends across the western
Atlantic from 26N80W to 29N75W. Scattered moderate convection
prevails along the trough and over the adjacent area from 26N-28N.
A stationary front extends from the end of the surface trough to
32N67W. Isolated convection is observed along the front. To the
east; a 1016 mb surface low is centered near 28N67W. Scattered
moderate convection is from 28N-31N between 60W-68W. Another
surface trough extends across the central Atlantic from 26N51W to
31N47W. Scattered moderate convection prevails within 100 nm on
either side of this boundary. Surface ridging dominates the
remainder of the basin. Expect for the Special Features low/tropical
wave to track northwest through the Bahama chain before reaching
the northwest Bahamas this weekend. Tropical Storm Gaston is
will remain east of 60W as it tracks northwest before turning
northward by Sunday.

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