Tropical Weather Discussion
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AXNT20 KNHC 132331

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
623 PM EST Wed Dec 13 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 1800 UTC surface analysis and satellite imagery through
2315 UTC.


A tight pressure gradient between a 1033 mb high pressure located
just south of the Azores and a low pressure system over western
Africa is resulting in strong to mimimal gale force winds in the
High Seas Forecast area called Agadir, along the coast of
Morocco. Very rough seas are within the area of these winds.
Winds and seas are forecast to gradually diminish tonight into
Thu. Please, refer to the Meteo-France High Seas Forecast for
more details.

The monsoon trough extends from the African coast near 07N12W to
06N18W. The Intertropical Convergence Zone axis continues from
06N18W to the coast of NE Brazil near 03N51W. Scattered moderate
convection is within about 60 nm N of the ITCZ axis between 23W-


A reinforcing and dry cold front is dissipating along 22N. A 1019
mb high pressure has developed over the NE Gulf while a 1023 mb
high pressure is near Tampico, Mexico. Under this weather
pattern, mainly light to gentle winds are noted across the Gulf
region with the exception of moderate northerly winds across the
SE waters, including the Yucatan Channel. Broken cold air
stratocumulus clouds are still noted over the eastern Gulf in
the wake of the dissipating front. Water Vapor imagery shows a
band of transverse high clouds over northern Mexico and the NW
Gulf in association with a subtropical jet, that is drawing
upper level moisture from the EPAC region into the Gulf of
Mexico. Looking ahead, another cold front is forecast to enter
the northern Gulf Thu, then reach from the Florida Big Bend area
in the NE Gulf to near Tampico Mexico by Fri afternoon, then
stall from Tampa to the Bay of Campeche on Sat before lifting
back to the W and NW through Sun. Gale force winds are possible
along the coast of Mexico near Tampico Fri night and Sat.

A weakening stationary front extends from northern Haiti to the
easternmost tip of Jamaica to the SW Caribbean near 11N80W. A
wide band of multi-layered clouds with embedded showers is
associated with the front. A well defined swirl of low clouds is
along the frontal boundary near 13N79W moving southward. This
front produced heavy rains over eastern Cuba Sunday through
Thuesday. The front will continue to dissipate to a remnant
trough tonight. Moisture associated with this trough is forecast
to move westward across the western Caribbean Thu and Fri in an
easterly wind flow. An earlier scatterometer satellite pass
showed moderate to locally fresh northerly winds across the
Windward Passage in the wake of the front. Gentle to moderate
trades are noted E of the front over the east and central
Caribbean, with moderate to fresh winds within about 90 nm of
the coast of Colombia. Winds are forecast to increase to 20-25
kt over the south-central Caribbean on Thu night, with gale
conditions possible Sat night and Sun night as high pressure
builds N of area. A reinforcing and dry cold front has reached
western Cuba. This will reinforce the cool and dry airmass over
western Cuba. Temperatures could drop below 10 degree Celsius
(50F)in some places across the Havana-Matanzas plains overnight

Cloudiness has increased over Hispaniola today due to the
proximity of a weakening stationary front that currently crosses
northern Haiti. Isolated to scattered light to moderate showers
are still possible tonight and early Thu. Then, moisture will
diminish later on Thu as the frontal boundary continues to weaken
and begins to drift westward as a trough.

A reinforning cold front enters the forecast area near 31N63W and
continues SW across the central Bahamas into western Cuba. Fresh
to strong W-NW winds follow the front but mainly N of 27N based
on latest scatterometer data. A weakening stationary front is
farther east and stretches from 31N60W to northern Haiti into
the Windward Passage and the Caribbean Sea. Fresh to strong S-SW
winds are aslo noted ahead of this front N of 27N to about 55W.
The reinforcing cold front will continue to move SE while
gradually dissipating on Thu. The stationary front will also
dissipate on Thu. A ridge will then build along 25N in the wake
of the secondary front. Another cold front is forecast to move
off the NE Florida coast early Fri, reach from Bermuda to South
Florida Sat, then reach from 24N65W to eastern Cuba early Sun.
The remainder of the Atlantic Ocean is under the influence of a
1033 mb high pressure located just south of the Azores. This
high extends a ridge SW to near the NE Caribbean.

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