AXNT20 KNHC 201150

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
649 AM EST Fri Jan 20 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
1130 UTC.


A cold front is over the western Atlantic from 32N53W to 25N57W
to 23N65W moving east at 10 to 15 kt. Winds reaching gale force
are noted north of 28N, within 180 nm both ahead of the front and
following the front. The gales will persist into the afternoon,
before diminishing late in the day. See latest NWS High Seas
Forecast under AWIPS/WMO headers HSFAT2/FZNT02 KNHC for more


The monsoon trough extends from the African coast near 06N11W to
05N11W. The intertropical convergence zone continues from 05N11W
to the coast of South America near 02S42W. Scattered moderate
isolated strong convection is observed within 120 nm either side
of the ITCZ between 18W and 33W.



A vigorous short wave trough in the mid levels of the atmosphere
was supporting a squall line across the northern Gulf of Mexico at
06 UTC. Strong thunderstorms along the squall line have since
disspated, leaving mostly lower to mid level cloudiness across the
northeast Gulf. Areas of fog reducing visibility to 3 to 5 nm are
noted in various offshore platforms in the northwest Gulf. A
somewhat tight pressure gradient between 1017 mb high pressure
centered over the Bahamas and a surface trough over central Mexico
was allowing moderate to fresh southerly winds over the south-
central Gulf of Mexico, as noted in a 06 UTC scatterometer pass.
Elsewhere gentle to moderate south the southeast winds persist
with 2 to 4 ft seas.

Showers and thunderstorms will accompany a strong cold front
forecast to move into the northwest Gulf Saturday night, reaching
from southeast Louisiana to near Tampico Mexico by Sunday morning,
and from the Florida Big Bend to the Yucatan Peninsula by Sunday
evening. Strong to gale force winds are possible behind the front
Sunday through Monday across the northern and central Gulf,
possibly spilling into the southeast Gulf, with seas building as
high as 16 to 19 ft. Conditions will gradually improve from west
to east Monday night through Tuesday night as high pressure builds
in behind the front.


1017 mb high pressure centered over the central Bahamas is
maintaining generally light to gentle anticyclonic flow across the
north central and northeast Caribbean and Tropical North Atlantic
regions. Seas are 3 to 5 ft in these areas. Fresh trade winds are
noted off the central coast of Colombia, and over the Gulf of
Honduras between the high pressure to the east and troughing over
southern Mexico.

Trade wind flow will diminish over the south central Caribbean
through early next week as the high pressure weakens and shifts
east ahead of an approaching cold front. The front is forecast to
reach the Yucatan Channel and the northwest Caribbean Sunday
night, accompanied by strong winds and building seas. The front
will reach from the Windward Passage to the eastern coast of
Nicaragua Monday night, with strong southwest winds expected near
the Windward Passage just ahead of the front. Over the tropical
north Atlantic waters, expect continued mainly gentle to moderate
trade winds and seas of 4-6 ft.


Deep layer subsidence will support dry conditions with light to
gentle breezes for the next couple of days with partly cloudy
skies and little to no shower activity.


A weak 1017 mb high is centered over the central Bahamas near 24N75W.
Scattered showers and thunderstorms are evident within 150 nm
ahead of the cold front from 32N53W to 25N57W to 23N65W. 1025 mb
high pressure is centered near 32N29W, supporting moderate to
fresh trade winds across the Azores and from 15N to 20N between
20W and 27W.

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