Tropical Weather Discussion
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AXNT20 KNHC 161020

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
618 AM EDT Wed Aug 16 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 0600 UTC surface analysis and satellite imagery through
1015 UTC.


Hurricane Gert is centered near 36.0N 68.4W at 16/0900 UTC or
about 285 nm NW of Bermuda moving NE at 18 kt. Estimated minimum
central pressure is 975 mb. Maximum sustained wind speed is 80 kt
with gusts to 100 kt. Numerous moderate to isolated strong
convection is from 35N-38N between 66W-70W. See latest NHC
forecast/advisory under AWIPS/WMO headers MIATCMAT3/WTNT23 KNHC
for more details.


A tropical wave is in the central Atlc associated with a 1011 mb
low pressure located near 13N34W. The wave axis extends from
19N34W to the low to 10N34W and has been moving W at 15-20 kt.
The wave is in a region of low to moderate vertical wind shear,
however intrusion of Saharan dry air and dust to the wave
environment limit convection to scattered moderate within 200 nm
NW quadrant of low pressure center. Showers and thunderstorms
continue to show some signs of organization in association with
the area of low pressure. Gradual development of this system is
possible before upper-level winds become less conducive for
development by the weekend.

A tropical wave is E of the Lesser Antilles with axis extending
from 21N57W to 10N60W, moving W at 25 kt. The wave is in a region
of moderate to strong vertical wind shear and continue to be
affected by Saharan dry air and dust, which is limiting
convection to scattered to isolated showers within 175 nm of its

A tropical wave is in the W Caribbean with axis extending from
21N79W to 09N80W, moving W at 20-25 kt. The wave is in a region
of low to moderate vertical wind shear and dry air subsidence,
which is limiting convection to isolated showers within 120 nm of
its axis.


The monsoon trough extends from the African coast near 12N16W to
09N22W to 13N30W to 13N40W to 14N45W to 12N48W. The Intertropical
Convergence Zone axis extends from 12N48W to 10N58W. Outside of
convection associated with the tropical waves, scattered heavy
showers and isolated tstms are off the W African coast from 08N
to 16N E of 22W associated with the next tropical wave that will
emerge to E Atlc waters later today. Otherwise, a 1011 mb low
embedded in the monsoon trough near 14N45W support scattered
showers from 12N to 16N between 43W and 51W.



Upper level divergent flow persists over the northern Gulf coast
between a broad upper level low centered NW of the Yucatan
Peninsula near 22N92W and an upper level anticyclone centered
over Georgia adjacent waters near 31N80W. Scattered showers and
tstms are occurring over Louisiana adjacent waters N of 27N
between 90W- 94W. Isolated showers are over the E Bay of
Campeche associated with a surface trough that extends from
23N87W to 17N94W. Otherwise, the E Gulf is under the influence
of a surface ridge anchored by a 1017 mb high centered near
27N84W. Gentle to moderate SE flow is W of 90W while light to
gentle variable flow is over the eastern half of the basin. The
high is expected to persist across the NE Gulf waters through
Friday. A surface trough will develop each evening across the
Yucatan peninsula shifting W into the Bay of Campeche during the
overnight hours. Locally higher winds can be expected in the
vicinity of the trough axis.


A tropical wave is in the W Caribbean supporting isolated showers
and tstms. This tropical wave will continue to propagate westward
across the remainder of the basin through tonight. Another
tropical wave is E of the Lesser Antilles where it is supporting
scattered to isolated showers. This second wave will move into E
Caribbean waters later this morning and is forecast to support
showers across Puerto Rico and adjacent waters. The wave will
move to the central basin Thursday supporting showers across
Hispaniola. Diffluent flow between an upper ridge located NE of
Jacksonville, Florida and an upper low centered N of Hispaniola
continue to support isolated showers over the Windward Passage
and  E Cuba adjacent waters. Otherwise, fresh to strong winds in
the south-central waters are expected through Thursday with
moderate to fresh trades elsewhere.


Showers and tstms are forecast to start overnight due to an
approaching tropical that will be entering the E Caribbean this
morning. The tropical wave will move over the central Caribbean
Thursday supporting showers across the Island.


Trailing moisture associated with Hurricane Gert N of the area
continue to support isolated showers in the SW N Atlc between 70W
and 76W. Otherwise, the remainder of the basin generally N of 20N
is under the influence of the Azores subtropical high which
supports fair weather. For information about tropical waves, see
section above.

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