Area Forecast Discussion
Issued by NWS Central Illinois

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546
FXUS63 KILX 141645
AFDILX

AREA FORECAST DISCUSSION
National Weather Service Lincoln IL
1045 AM CST SUN FEB 14 2016

.UPDATE...
ISSUED AT 1045 AM CST SUN FEB 14 2016

Updated the forecast to address snowfall today and will continue
the winter weather advisory across CWA through 6 pm today. Second
and larger band of light to moderate snow had spread east across
IL by late this morning, with back edge of this snow just west of
CWA. Though more wrap around mainly light snows were over central
and eastern IA and will spread across northern CWA during the
afternoon, keeping them in the snow longer and also higher total
snowfall amounts of 3-4 inches. Central and southeast CWA to see
an additional 1-3 inches rest of today with total of 2-3 inches,
though heavier bands of snow from Springfield south to Litchfield
and east toward Taylorville and Shelbyville. Southeast winds of
10-20 mph and gusts to around 25 mph to continue some blowing and
drifting snow. Temps at 1030 am were in the upper teens and lower
20s. Highs this afternoon in the mid to upper 20s look on track.
540 dm 500 mb low over east central Iowa to track into northern/ne
IL by 00Z/6 pm today and then into nw Ohio by 06Z/midnight
tonight. This feature associated with the wrap around snows in
central/eastern IA that moves across the northern CWA during the
afternoon. Otherwise back edge of snow to spread eastward across
central/se IL during the afternoon and some patchy freezing
drizzle appears in sw CWA late this afternoon and rest of CWA
during tonight as we lose mid level clouds.

&&

.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 12Z TAFS through 12Z Monday morning)
ISSUED AT 500 AM CST SUN FEB 14 2016

First wave of snow was pushing into our eastern TAF sites this
morning with a break in the snow through about 15z before another
round of snow and IFR cigs moves in for the rest of the day.
Latest surface observations to our west indicates cigs improve
to low VFR with occasional MVFR cigs/vsbys in very light snow.
However, across western Iowa into northwest Missouri, a band
of light to moderate snow was located and based on the present
movement of the snow, it will push into our western areas between
14z-16z, and over the far eastern TAF sites by 18z. Cigs and Vsbys
will lower to IFR to occasional VLIFR where some of the heavier
bands of snow setup. The snow is expected to taper to flurries
by late afternoon or early this evening and as the precip starts
to edge off to our east, there is the threat for some patchy
freezing drizzle this evening, mainly from 00z-06z. Due to the
patchy nature of the precip this evening, will not include in
the TAFs at this time, but something to keep an eye on with
later forecasts today.

Southeast winds of 12 to 17 kts are expected today with a few
gusts around 23 kts into this afternoon with winds turning
more into a southerly direction tonight with speeds of 10 kts
or less.

&&

.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.

&&

$$

UPDATE...07
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Smith



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