Tropical Weather Discussion
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AXNT20 KNHC 161031

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
631 AM EDT Sun Jul 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
1100 UTC.


A central Atlantic tropical wave has an axis extending from
04N48W to 15N45W, moving westward at 5 to 10 knots. The wave has
large areas of dry Saharan air to its NE and NW, but remains
embedded in an area of deep layer moisture. Scattered moderate and
isolated strong convection is present from 05N to 10N between 46W
and 55W.

A central Caribbean tropical wave has an axis extending from
northern Colombia at 09N76W to between Haiti and Jamaica at
19N75W, moving westward around 20 kt. Scattered moderate and
isolated strong convection associated with this wave is over
northern Colombia, extreme western Venezuela and the adjacent
coastal waters from 10N to 13N between 71W and 80W. The latest
rawinsonde sounding from San Juan suggests some of this convection
could produce gusty winds. The wave is expected to exit the
central Caribbean this afternoon, cross the western Caribbean
Monday and Tuesday.

A western Caribbean tropical wave has an axis extending from
western Costa Rica at 09N84W to the Western Tip of Cuba near
22N84W, moving westward at around 20 knots. TPW satellite imagery
shows this wave is only embedded in a modest layer of moisture.
There is no significant convection associated with this wave. This
wave is entering Central America and will cross the remainder of
the western Caribbean and enter the Yucatan Peninsula by this


The Monsoon Trough axis extends from Senegal in west Africa near
14N17W to 11N22W to 08N49W. The ITCZ continues from 08N49W to just
north of the coast of Suriname in South America near 06N54W.
Aside from the convection related to the tropical wave near 46W,
scattered moderate and isolated strong convection is present from
09N to 12N between 15W and 30W and from 03N to 12N between 30W
and 46W.



A weak surface trough stretches from 25N94W to 27N92W in the
north central Gulf of Mexico to the south of Louisiana. Otherwise,
a weak high pressure ridge along the northern Gulf Coast is
maintaining a light to gentle SE winds over the Gulf. Upper-level
winds converging between high pressure along the northern Gulf
Coast and a low pressure trough over the southern Gulf is
inhibiting convection, except for the convection associated with
diurnal troughing over the Yucatan, which is beginning to move
over the Bay of Campeche. This weather pattern is expected to
continue over the Gulf during the next 24 hours.


A couple of tropical waves are moving through the Caribbean Sea.
See the tropical waves section above for details. Other than the
tropical wave over the central Caribbean, upper-level winds
converging over the basin between high pressure over northern
South America and a low pressure trough over Hispaniola and Cuba
are inhibiting convection. A relatively light pressure gradient
over the area is generating light to moderate trades, except for
fresh to locally strong trades along the coast of Colombia and in
the vicinity of the Gulf of Venezuela. Fresh to strong trades are
expected to return to the central Caribbean by Monday evening as
high pressure to the north strengthens.


Generally fair weather prevails across the island. A passing
tropical wave produced some convection over Haiti yesterday
evening but shower coverage over western Hispaniola has
diminished. Drier weather is anticipated today as the tropical
wave over the central Caribbean continues heading farther west.


A tropical wave continues crossing the central Atlantic. See the
tropical waves section above for details. A surface trough is
analyzed over the western Bahamas from 24N79W to 26N78W. The
trough is interacting with a small upper-level low centered near
26N79W to produce isolated thunderstorms between the Bahamas and
Cuba within 45 nm either side of a line from 22N75W to 24N79W.
This system is expected to continue heading west toward the
Straits of Florida today and into the eastern Gulf of Mexico
tonight. Other troughs are analyzed from 26N48W to 30N44W and
from 27N67W to 30N65W. Both of these troughs are weak and neither
one of these has significant convection associated with it. The
remainder of the basin remains dominated by a broad surface ridge,
anchored by a 1028 mb high centered just SW of the Azores near

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