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Atlantic Tropical Weather Discussion

AXNT20 KNHC 262354

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
754 PM EDT FRI AUG 26 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.

Tropical Storm Gaston is centered near 26.2N 49.7W at 26/2100 UTC
or about 870 nm ESE of Bermuda and about 890 nm NE of the northern
Leeward Islands moving NW at 15 kt. Estimated minimum central
pressure is 997 mb. Maximum sustained wind speed is 55 kt with
gusts to 65 kt. Scattered moderate and isolated strong convection
is from 25N-28N between 48W-51W. Scattered moderate convection is
elsewhere from 23N-27N between 40W-46W...and from 24N-29N between
44W-58W. See latest NHC Forecast/Advisory under the AWIPS/WMO
headers MIATCMAT2/WTNT22 KNHC for more details.

Tropical wave extends from 10N25W to 17N23W moving W at 10-15 kt.
The wave coincides with subtle 700 mb troughing noted in global
model data between 20W-28W that remains embedded within the
Monsoon Trough axis. No significant deep convection is occurring
with the wave at this time.

Tropical wave extends from 09N81W to 19N80W moving W at 15-20 kt.
A portion of energy associated with the wave fractured north a
couple days ago as the wave entered the Caribbean Sea...with that
energy now analyzed as a 1009 mb low and surface trough extending
across the SE Bahamas and eastern Cuba. The remaining westward
moving wave energy however is noted in global model data as 700
mb troughing and 850 mb relative vorticity fields S of 20N between
78W-84W. Isolated moderate convection is from 15N-20N between
79W-82W. Scattered moderate convection is S of 13N between 75W-
85W...including portions of Panama...Costa Rica...and southern
Nicaragua. This convection is likely enhanced due to the close
proximity of the Monsoon Trough along 09N.

The Monsoon Trough extends from 20N16W to 11N24W to 05N43W.
Isolated moderate convection is within 180 nm either side of a
line from 10N14W to 04N35W to 04N44W.


Diffluent flow aloft is noted on water vapor imagery N of the
influence of an upper level low centered over NE Mexico near
25N99W and an upper level ridge centered over the Yucatan
peninsula near 19N88W. The diffluence maximized N of 24N between
84W-91W is supporting ample mid-level lifting dynamics and a
surface trough analyzed at 26/2100 UTC from 24N88W to 28N89W.
Scattered showers and tstms are resulting within light to moderate
E to NE winds from 23N-30N between 84W-90W. In addition...
scattered showers and tstms are occurring farther east across the
western coast of the Florida peninsula...most likely enhanced due
to seabreeze interactions this evening. This overall synoptic
pattern is expected to persist through Sunday night as a fractured
portion of energy associated with a tropical wave currently in the
western Caribbean Sea moves across the Florida Straits and into
the SE Gulf waters early next week. Increased precipitation with
locally heavy rainfall and possible localized flooding is
anticipated this weekend across the the southern Florida
peninsula and Florida Keys.

Much of the basin is under the influence of lower surface pressure
values given a tropical wave currently analyzed along 81W and the
northern energy of the wave that has fractured north and remains
focused on a 1009 mb low centered across the SE Bahamas near
23N75W. The tropical wave is providing focus for scattered showers
and tstms in the vicinity of 18N82W and generally S of 13N between
73W-85W...including inland portions of northern Colombia and
Central America. Other convection...likely supported by mid-level
dynamics is occurring across Puerto Rico...the Mona Passage...and
Hispaniola N of 15N between 65W-72W. This complex tropical wave
and associated energy to the north is expected to continue W-NW
through Sunday and likely bring an increased probability of
precipitation to Central America and the Yucatan peninsula with
potential for locally heavy rainfall...localized flooding...and
mud slides across the region. Farther east...moderate to fresh
trades will re-establish themselves E of 80W and increase fresh to
strong across the central Caribbean by Monday night into Tuesday.

Scattered showers and tstms associated with the broad low
pressure area NW of the island are expected to persist through the
overnight period into Saturday as the low moves W-NW during the
next 24 hours. Gusty winds...heavy rainfall...flash flooding...
and mud slides are possible across the island through Saturday.

Aside from Tropical Storm Gaston...a 1009 mb low is centered
across the SE Bahamas near 23N75W moving W-NW at 10-15 kt. Low-
level streamline analysis indicates surface troughing extending
from near Bermuda as a 1014 mb low near 31N65W SW through the SE
Bahamas low to the broad area of low pressure across the western
Caribbean Sea focused on a tropical wave along 81W. A large area
of scattered showers and tstms are occurring from across
Hispaniola and Puerto Rico NW to across the Turks and Caicos
Islands and SE Bahamas. Additional isolated showers and tstms are
occurring S of 28N W of 78W to the Florida coast. With regards to
the 1014 mb low centered near Bermuda...most of the ongoing
scattered showers and tstms are occurring within the eastern
periphery of an upper level low centered near 32N68W from 26N-33N
between 63W-66W. The low is expected to remain stationary through
Saturday and begin slowly drifting W on Sunday. Lastly...the
eastern Atlc is under the influence of a surface ridge anchored by
a 1021 mb high centered near 35N22W.

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