Tropical Weather Discussion
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AXNT20 KNHC 151714

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
114 PM EDT Tue Aug 15 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
1645 UTC.


Hurricane Gert is centered near 32.8N 72.0W at 15/1500 UTC or
about 365 nm W of Bermuda moving N-NE at 9 kt. Estimated minimum
central pressure is 986 mb. Maximum sustained wind speed is 65 kt
with gusts to 80 kt. Numerous moderate to strong convection is
within 90 nm in the southeast semicircle of the center. Elsewhere, scattered
moderate convection is from 29N to 31N between 70W and 73W. See
latest NHC forecast/advisory under AWIPS/WMO headers
MIATCMAT3/WTNT23 KNHC for more details.


A tropical wave is W of the Cape Verde islands reaching from
20N29W to 1010 mb low pressure near 13N32W to 10N32W, moving west
at 10 kt. Scattered convection is noted over much of the region
from 11N to 14N between 30W and 33W. The wave is in a region of
low vertical wind shear, however intrusion of Saharan dry air and
dust to the wave environment limit deep convection. Slow
development of this system is anticipated during the next day or
two, but conditions are forecast to become a little more conducive
for tropical cyclone formation by later in the week while the
system moves westward over the tropical Atlantic.

A tropical wave is in the central Atlc with axis extending from
20N52W to 11N54W, moving W at 10 to 15 kt. The wave is entering a
region of moderate to strong vertical wind shear and is being
severely affected by extensive Saharan dry air and dust, which is
hindering convection at the time.

A tropical wave is in the central Caribbean with axis extending
from northeast Colombia to central Hispaniola. The wave is in a
region of strong vertical wind shear and dry air subsidence, which
is hindering deep convection at the time. Divergent flow aloft
between an upper trough over the area and an upper ridge well to
the northwest is support scattered moderate convection from 150 nm
south of the Dominican Republic through the Mona Passage.


The monsoon trough extends from the coast of W Africa near 15N17W
to 1010 mb low pressure near 13N32W to a 1009 mb low pressure
area centered near 14N43W, where the intertropical convergence
zone starts and continues to 13N53W then on to near Trinidad.
Scattered moderate to isolated strong convection extends from 06N
to 11N E of 20W. Scattered moderate convection is within 120 nm of
the 1010 mb low pressure near 14N43W.



A ridge extends from the Straits of Florida to the coast of south
Texas. A broad upper level low is centered just north of the
Yucatan peninsula, which supports isolated showers there and in
the Yucatan Channel. Diffluent flow in the northwest periphery of
the low support similar shower activity off the SE coast of
Louisiana and Mississippi. The gradient between the ridge and
lower pressure over north central Mexico is supporting moderate to
fresh southerly winds across the western Gulf, and light to gentle
breezes elsewhere. A surface trough will develop each evening
across the Yucatan Peninsula shifting W to the Bay of Campeche
during the overnight hours. Locally higher winds can be expected
west of the trough axis.


A tropical wave is moving through the central Caribbean. Please
see section above. The tropical wave will continue to propagate
westward across the western Caribbean through late Wednesday. A
few showers and thunderstorms are active north of western Panama
off Boca del Toro. Showers are also ongoing over the northwest
Caribbean from near Swan Island to the Bay Islands, in the
divergent flow aloft southeast of the upper low centered north of
the Yucatan peninsula. Otherwise, fresh to strong winds in the
south-central basin will through Thursday.


An upper level trough reaching across the area from the central
Atlantic will drift WSW to the north and across the island over
the next couple of days supporting scattered showers over the
island and adjacent waters through Thursday.


Scattered showers and tstms are N of 28N between 70W and 74W associated
with the rainbands of Hurricane Gert centered north of the area.
See Special Features section for more information on Gert.
Otherwise, the remainder basin generally N of 20N is under the
influence of the Azores high, which supports fair weather. For
information about tropical waves, see section above. Farther east,
numerous moderate to isolated strong convection is noted across
sub-Saharan West Africa, related tropical wave activity moving
through the region. Some of this convection is observed within 180
nm of the coast from Liberia to Senegal.

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