Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 070534
AFDILX

AREA FORECAST DISCUSSION
National Weather Service Lincoln IL
1134 PM CST SAT FEB 6 2016

.UPDATE...
ISSUED AT 852 PM CST SAT FEB 6 2016

Quiet weather is expected across central and southeast Illinois
overnight. It will be milder tonight than last night as clouds and
southerly winds increase. However, the clouds are taking their
time getting here thanks to the dry air in place. This may allow
temperatures to fall a bit more than current forecast. Still,
temperatures haven`t fallen too hard yet, so will leave them alone
for now. Main change to current forecast will be to slow the
arrival of the thicker cloud cover.

&&

.SHORT TERM...(Tonight)
ISSUED AT 254 PM CST SAT FEB 6 2016

Central and southeast IL enjoying a sunny day with milder
temperatures in the middle 40s to lower 50s (Flora and Salem up to
54F). Southwest winds of 8-16 mph and few gusts around 20 mph over
central IL and lighter sw winds 5-10 mph in southeast IL at mid
afternoon.

Upper level trof and a pair of embedded cutoff upper level lows
over the lower MS river valley will keep its clouds southeast of the
Ohio river as it tracks across the Southeast States tonight.
Meanwhile a northern stream short wave/trof over eastern MT with 996
mb surface low pressure over southern Canadian Rockies, will track
into the upper Midwest by 12Z/6 am Sunday while surface low
approaches nw MN. Broken mid/high clouds over the northern Plains
and into nw IA will spread se across central IL during overnight as
fair skies this evening become partly to mostly cloudy overnight.
Milder lows overnight mostly in the lower 30s with sw winds 5-15
mph. Temperatures to fall fairly quickly this evening after sunset
in dry air mass and fair skies. Increasing clouds and sw winds
overnight to temper temperature fall.

.LONG TERM...(Sunday through Saturday)
ISSUED AT 254 PM CST SAT FEB 6 2016

One more unseasonably mild day on Sunday before much colder air
starts to invade the Midwest early next week. An upper level
shortwave forecast to dig southeast into the lower Great Lakes
later on Sunday into early next week which will deliver the next
batch of Arctic air to the forecast area starting on Monday.
Strong surface low expected to pass well north of our area on
Sunday but the southwesterly flow ahead of the frontal boundary
will help keep our temperatures quite mild for the first week of
February, generally from the middle 40s far north to the lower 50s
south and west. With the better forcing and deeper moisture
remaining north on Sunday, it appears the higher probability for
precip will also remain north of our area through most of the day.
By late afternoon and evening, models indicate some light QPF
possible over the far southeast as this area will be near the left
exit region of a speed max at 250 mb. Still, only worth slight
chance POPs during this time frame.

We look for better lift moving across the area with the deeper cold
advection which settles over the area late Sunday through Monday
night as the closed 500 mb system shifts across northern Illinois.
It is during this time that we will see higher POPs, but still low
QPFs across the forecast area with scattered snow showers from time
to time. We are still looking at an inch or less total
accumulation over the longer duration (late Monday night through
at least Tuesday morning). The time frame from Monday through
Monday night will need to be watched as temperatures will be below
freezing, a light accumulation of snow will occur accompanied by a
gusty northwest wind, which will produce some slick roadways,
especially when darkness sets in Monday evening.

Scattered snow showers or flurries will gradually end from west to
east by late Tuesday morning, although the latest ECMWF and Canadian
models have trended a bit slower as our strong cyclonic flow hangs
on a bit longer over the forecast area. We may need to hold on to at
least some flurries during the day on Tuesday if these trends start
to show a bit more consistency. In addition, a gusty northwest wind
is expected to hold across the area through Tuesday with gusts up
to around 30 mph at times driving wind chills down into the single
digits above and below zero Tuesday morning with our coldest wind
chill readings on Wednesday morning where we will see readings
around 10 below zero along and north of Interstate 74.

The stronger cyclonic flow will begin to weaken on Wednesday as the
center of the cold air settles east into the Midwest. Meanwhile, the
latest Canadian model indicates a quick moving shortwave dropping
southeast into the Plains during the day Wednesday producing a band
of light snow from north central Iowa southeast into western IL. The
ECMWF and GFS picks up on this wave but is about 6 hours slower in
bringing in the very light snow into western Illinois by Wednesday
night. Confidence on the timing and magnitude of these fast moving
shortwaves in the strong northwest flow this far out in time is poor
at best, so will continue to keep the forecast dry on Wednesday.

Each of these fast moving shortwaves embedded in the northwest flow
during the middle and latter portions of the work week will deliver
reinforcing shots of Arctic air to the region. So what looked like a
gradual moderating trend by late week or next weekend with previous
model runs, has been put on hold for now as temperatures during this
time frame look to be below normal over most of the forecast area.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 1130 PM CST SAT FEB 6 2016

VFR condtions should prevail across the central Illinois terminals
through the bulk of the 06Z valid time. A strong storm system
will dive into the Great Lakes region on Sunday. However, most of
the associated precipitation will stay north of the center of the
surface low through the daytime hours Sunday. A few snow showers
can`t be ruled out, at least at KPIA, by Sunday evening, but
chances are low enough to preclude mention at this time. The main
impacts locally will be increasing VFR level cloudiness, and
southwest winds gusting over 20 kts by early Sunday morning.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

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


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