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Atlantic Tropical Weather Discussion

AXNT20 KNHC 301039

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
639 AM EDT SAT JUL 30 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
1030 UTC.


A tropical wave is moving across the eastern Atlantic with axis
that extends from 19N28.5W to a 1010 mb low near 11N26W. These
features are moving west at about 10 kt. The wave is associated
with a low to mid-level trough extending northward to the west of
the Cabo Verde Islands along 27W. An earlier scatterometer pass
indicated strong southwest to west winds converging into the low,
supporting scattered moderate convection from 10N to 12N between
25W and 28W. This area has a medium potential for tropical cyclone
development during the next 48 hours.


A well defined tropical wave is moving across the central
Atlantic with axis from 19N50W to 10N50W, moving west at 15 to
20 kt. The tropical wave is evident as a broad and amplified low
to mid level trough between 45W and 55W with abundant deep-layer
moisture in SSMI Total Precipitation Water Vapor Imagery and
satellite derived winds. Recent scatterometer data depicts broad
surface troughing in the same vicinity. The gradient between the
trough and the subtropical ridge to the north is resulting in
fresh to strong trade winds from 13N to 22N between 45W and 55W,
with associated seas to 10 ft. The trade winds convergence is
also supporting scattered moderate convection from 14N to 16N
between 47W and 55W. As this wave moves west during the next
several days, fresh trades accompanied by potentially higher gusts
will move across the waters north of the Greater Antilles and
waters surrounding the Turks and Caicos, southeast Bahamas, and
eastern and central Cuba creating hazardous boating conditions.

A tropical wave is moving across the Bay of Campeche in the
southwest Gulf of Mexico with axis extending from 21N95W to
19N96W, moving west at 10 to 15 kt. This is interacting with an
upper level low centered over the coast of Mexico, and is
resulting in scattered showers and thunderstorms over much of the
southwest Gulf south of 22N and west of 94W. The tropical wave is
expected to gradually weaken over the next 24 hours as it moves
inland over southern Mexico.


The monsoon trough extends from 19N16W to the 1010 mb low
pressure near 11N26W mentioned in the special features section,
then continues westward to 10N50W. The intertropical convergence
zone extends from 10N50W to 09N60W. No significant convection is
noted outside the areas already discussed relating to tropical
waves and the low pressure near 11N26W.



A sharply elongated upper low remains centered along the coast of
the northern Mexican state of Tamaulipas. Divergence aloft on
the eastern side of the upper low was enhancing convection in the
Bay of Campeche related to the tropical wave over the southwest
Gulf. Otherwise deep layer ridging dominates the region, the
subtropical ridge reaching from the western Atlantic across
Florida into the eastern Gulf of Mexico. This will maintain gentle
to moderate breezes across the basin with 2 to 4 ft seas through
early next week.


An upper-level trough extending from over Haiti to the southwest
Caribbean is delivering a plume of deep layer moisture across the
east central Caribbean into the Virgin Islands, Puerto Rico and
Hispaniola. An associated surface trough shows up well on recent
Rapidscat data across the central Caribbean from just east of Cabo
Beata on the south coast of Hispaniola to the Gulf of Venezuela. A
line of showers and a few thunderstorms are active from the coast
of Colombia to the Mona Passage. Fresh to strong trade winds are
noted on west of the surface trough, off the coast of Colombia.
Fresh trades are also noted across the Leeward Islands into the
northeast Caribbean on the east side of the surface trough. The
Leewards and northernmost Windward Islands and surrounding waters
are in a relative dry slot currently between the upper trough to
the west and the approaching tropical wave, but will see increased
moisture and convection through today ahead of the approaching
tropical wave. Little change is expected elsewhere.


Divergence aloft and increased moisture on the east side of an
upper trough moving westward across Haiti will support scattered
mainly afternoon convection.


Two tropical waves are moving across the tropical Atlantic. Please
refer to the section above for details. A few showers and
thunderstorms are active currently over the far western Atlantic
from Hispaniola to the northern Bahamas, largely due to divergent
flow aloft between an upper trough reaching from southwest of
Bermuda to Haiti and an upper ridge farther to the northwest.
Meanwhile a 1018 mb surface high is centered off Abaco Island near
27N77W. To the east, an upper-level trough is reflected at the
surface as a trough that extends from 24N68W to Hispaniola.
Another surface ridge extends across the remainder of the basin
anchored by a 1030 mb high centered near 40N33W. Farther east, fresh
to strong northeast winds are observed across the Canary
Islands, between the ridge and lower pressure over northwest
Africa. Little change is expected through the next 24 hours.

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