Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 140924
AFDILX

AREA FORECAST DISCUSSION
National Weather Service Lincoln IL
324 AM CST SUN FEB 14 2016

.SHORT TERM...(Today)
ISSUED AT 324 AM CST SUN FEB 14 2016

08z/2am water vapor imagery shows a vigorous short-wave trough over
eastern Nebraska.  A narrow band of snow has developed well in
advance of this feature across the central sections of Iowa and
Illinois in association with strong 700-500mb layer frontogenesis.
Latest radar imagery/surface obs show the snow band centered along a
Galesburg...to Lincoln...to Marshall line.  This band is expected to
gradually lift northward over the next few hours, as frontogenetic
forcing shifts northward and weakens.  Snowfall of one half inch or
less will be likely with this initial burst of snow early this
morning. The main precip event will hold off until later this
morning as stronger/more widespread synoptic lift associated with
the short-wave arrives.  HRRR seems to be handling the current
precip field better than any other model, so have followed its
solution closely in the short-term.  It shows snow rapidly
developing in advance of the approaching wave and spreading eastward
into central Illinois between 15z and 18z.  Based on speed of wave,
a 4-5 hour period of light to moderate snow is expected from late
morning through mid-afternoon before the precip begins to diminish
from west to east late in the day.  Total snowfall still appears to
be 2-3 inches across most areas, with the highest totals of 4-5
inches focused along/northwest of the Illinois River.  Will continue
the Winter Weather Advisory through 6pm accordingly.

&&

.LONG TERM...(Tonight through Saturday)
ISSUED AT 324 AM CST SUN FEB 14 2016

All models show the strongest lift quickly shifting east of the area
late this afternoon into the early evening, suggesting a rapid end
to the accumulating snow.  Will linger chance PoPs across the north
and east through the evening, then will go dry across the board
overnight.  Forecast soundings show a loss of ice crystals within
the profile, resulting in a period of light freezing drizzle as the
precip ends.

Monday still appears to be a cool and mostly dry day: however, a few
of the models are showing some light precip with another short-wave
skirting through the area.  The GFS is the most bullish with precip,
while the NAM and ECMWF show very little.  Given presence of at
least weak lift, will carry slight chance PoPs for rain/snow across
the southern half of the KILX CWA Monday afternoon.

A more significant wave will push into the region on Tuesday,
bringing another round of light precip.  Models generally track the
500mb vort max right across central Illinois, resulting in most of
the precip being focused across the northern half of Illinois.
Thermal profiles will be cold enough to support snow initially late
Monday night into Tuesday morning: however, as temperatures climb
into the upper 30s and lower 40s, the snow will transition to a
rain/snow mix or all rain by Tuesday afternoon.  Minor snow
accumulations of 1 inch or less are expected during the morning
before the snow mixes with/changes to rain.

After that, the big weather story for the end of the week will be a
pronounced warming trend as upper-level ridging builds across the
Midwest.  High temperatures will reach the upper 40s and lower 50s
on Thursday, then will climb even higher into the upper 50s and
lower 60s by Friday.  A weak cold front will push through Illinois
on Friday, with 00z Feb 14 models now pulling back on their QPF.
Will still mention low chance PoPs for rain showers with FROPA on
Friday, followed by a return to mild/dry weather next weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 1140 PM CST SAT FEB 13 2016

Snow has begun in western parts of IL, but radar shows it is along
a narrow band. Believe this is just acting to moisten the lower
levels some. So thinking is not much snow will occur with this, so
will just have a TEMPO group at all sites overnight for 2hrs of
light snow with MVFR vis and cigs 3.5kft or above. Then as the
main wave reaches the area in the morning, more snow arrives,
starting around 15z at SPI and PIA with IFR vis and cigs in the
MVFR range. Based on HiRes models, that pockets of more intense
snowfall will be possible so will have TEMPO group at all sites
for vis below 1sm and cigs below 1kft...LIFR conditions. These
conditions will be in the late morning in the west to afternoon in
the east. As snow departs to the east, conditions will gradually
improve during the afternoon and then snow should completely stop
in the evening hours, though PIA and BMI may see light snow last
longer, being closer to the main mid level wave. Winds will be
southeast through the period. Wind speeds will around 10kts overnight
and into the morning hours, but then increase tomorrow with gusts
over 20kts. Once the snow begins to taper off, speeds will
decrease and winds will become more south-southeast.


&&

.ILX Watches/Warnings/Advisories...
Winter Weather Advisory until 6 PM CST this evening for
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Auten


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