Tropical Weather Discussion
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AXNT20 KNHC 121016

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
516 AM EST Tue Dec 12 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
0945 UTC.

The monsoon trough extends from the African coast near 07N12W to
07N16W. The Intertropical Convergence Zone axis extends from
07N16W to 02N40W to the Equator near 50W. Isolated moderate
convection is from 03N-06N between 10W-14W...and from 03N-06N
between 38W-41W. Widely scattered moderate convection is from
04N-08N between 20W-28W.


A surface ridge extends across the entire basin anchored by a
1027 mb high centered offshore of eastern Mexico near 23N97W.
Gentle to moderate anticyclonic winds are noted across the basin
this morning with slightly stronger moderate to fresh W-NW winds
occurring N of 28N. The stronger winds are occurring in advance
of a weak cold front analyzed across the lower Mississippi River
valley and central Texas. The front is forecast to emerge off the
SE CONUS coast later today introducing a brief period of fresh
W-NW winds to the northern waters shifting eastward into the
eastern waters Tuesday afternoon into the evening. The troughing
will be quick to clear east of the basin by Wednesday with
moderate northerly winds prevailing through Thursday.

The primary feature across the basin is the stationary front
extending from the Windward Passage SW to the coast of western
Panama near 10N81W. Widely scattered showers and isolated tstms
are occurring generally S of 19N between 75W-83W. Much of this
convection is supported aloft by a divergent upper level pattern
on the western periphery of an upper level anticyclone anchored
over northern Colombia near 08N75W. East of the anticyclonic
circulation...dry NW flow prevails providing overall stability to
the central and eastern Caribbean this evening. A few isolated
showers are noted on satellite imagery E of 72W...but remain
shallow and embedded within gentle to moderate trades. The front
is forecast to remain stationary across the western Caribbean and
gradually weaken through Thursday.

Fair weather conditions prevail across the island this morning
while a stationary front remains analyzed across the Windward
Passage region to the W. Isolated showers are possible within 60
nm either side of the front which is expected to remain stationary
and begin weakening through Thursday.

Water vapor imagery indicates broad middle to upper level
troughing over the eastern CONUS and western North Atlc waters
supporting a stationary front extending from 32N59W to the Turks
and Caicos near 22N73W to the Windward Passage and into the SW
Caribbean Sea. Isolated showers are occurring within 120 nm either
side of the front. Otherwise...the remainder of the SW North Atlc
waters are under the influence of a surface ridge anchored over
the Gulf of Mexico and portions of eastern Mexico with axis
extending E-NE across the Florida peninsula to a 1018 mb high
centered near 31N70W. Farther east...water vapor imagery
indicates a middle to upper level low centered near 25N50W. The
associated surface trough extends from 15N58W to 23N53W with
scattered showers and tstms occurring NE of the troughing from
15N-32N between 43W-50W.

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