Tropical Weather Discussion
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000
AXNT20 KNHC 132316
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
616 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.

...SPECIAL FEATURES...

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 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.

...ITCZ/MONSOON TROUGH...
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-
30W.

...DISCUSSION...

GULF OF MEXICO...
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.

CARIBBEAN SEA...
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
tonight.

...HISPANIOLA...
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.

ATLANTIC OCEAN...
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.

For additional information please visit
http://www.hurricanes.gov/marine

$$
GR




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