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Atlantic Tropical Weather Discussion

AXNT20 KNHC 300545

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
145 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 0000 UTC surface analysis and satellite imagery through
0530 UTC.


A tropical wave is moving across the eastern Atlantic with axis
that extends from 18.5N28W to a 1010 mb low near 12N26W. 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 09N to 11N between
25W and 28W. This area has a medium potential for tropical cyclone
development during the next 48 hours.


A tropical wave is moving across the central Atlantic with axis
from 19N49W to 10N49W, moving west at about 15-20 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 9 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 21N91W to
18.5N93W, moving west at 10 to 15 kt. This is coinciding with the
local evening surface trough that forms off the west coast of
Yucatan. The tropical wave is expected to gradually weaken over
the next 24-36 hours while enhances convection across the Yucatan
Peninsula, southern Mexico and the Bay of Campeche.


The monsoon trough extends from 22N17W to the 1010 mb low
pressure near 12N26W mentioned in the special features section,
then continues westward to 10N50W. The intertropical convergence
zone extends from 10N50W to 09N60W. Aside from the convection
related to the tropical waves and the low pressure, scattered
moderate convection is observed within 120 nm south of the monsoon
trough between 35W and 50W.



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/trough early in the
evening, but this has since weakened. 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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