Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 122323

Area Forecast Discussion
National Weather Service Lincoln IL
523 PM CST Thu Jan 12 2017

.SHORT TERM...(This evening through Friday)
ISSUED AT 319 PM CST Thu Jan 12 2017

A strong cold front has pushed southeast to near the Ohio river at
mid afternoon, taking rain showers southeast of CWA. Northwest winds
of 8-15 mph and few gusts to 20 mph were ushering in colder air to
central and southeast IL today. Mercury levels at mid afternoon
range from 22F at Galesburg to 42F at Lawrenceville and Mount Carmel
airport. Overcast stratus clouds below 1.5k ft over CWA were
breaking up in nw IL closer to 1033 mb arctic high pressure over
western ND and ridging into the central plains.

Latest forecast models take cold front southeast across KY/TN
tonight as arctic high pressure moves into the upper MS river valley
Friday morning. This should decrease clouds from nw to se late today
and into tonight and keeping precipitation south of CWA through
early Fri morning. Lows tonight range from mid teens from IL river
nw to the mid to upper 20s in southeast IL. Overrunning will set up
over southern CWA during Friday with clouds spreading back northward
during Fri morning as skies become mostly cloudy to overcast by
Friday afternoon. Also will see light freezing rain spread into
areas south of a Jacksonville to Mattoon to Robinson line by late
Friday morning and getting as far north as a Lincoln to Danville
line by sunset Friday. Northern fringe of system will also have
chance of sleet while south of I-70 could see light rain as well.
Will continue the winter storm watch for central and southern CWA
starting Friday afternoon, though the wintery mix may not reach
northern part of watch area from I-72 north until late Friday
afternoon. Highs Friday range from upper 20s nw of I-55 to the mid
30s in southeast IL.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 319 PM CST Thu Jan 12 2017

The frontal boundary stalling just southeast of the forecast area
and broad surface high pressure moving eastward through the Great
Lakes Region over the weekend will provide the main ingredients for
winter weather over the weekend into Monday morning as the high
feeds cold surface air into the area from the north/east, and the
frontal boundary allows a couple of disturbances to propagate
northeastward into the area brining precipitation. A persistent warm
layer aloft will cause any precipitation to fall as rain, however
temperatures will be below freezing for the nighttime periods...only
rising to near or a few degrees above freezing in the afternoon.
Highs will potentially get a bit more solidly above freezing south
of I-70 in the upper 30s. Therefore, periods of freezing rain can be
expected through the weekend, especially the nighttime periods.
Total ice accumulations could exceed a quarter inch from roughly I-
72 southward and I-57 westward, although at this point it appears
the breaks in accumulation and the potential melting in the
afternoon periods may prevent any ice buildup over one quarter inch
so have kept the winter storm watch going and have not upgraded any
portion to warning or advisory so far. Also added remaining portions
of northern CWA to the watch starting Midnight Saturday night and
going to Monday morning.

Strong warming expected to take place Monday as a low tracks NW of
the area bringing strong warm advection and heavier rainfall which
could result in rainfall up to an inch Monday through Tuesday.
Precipitation chances taper off through midweek and mainly based on
timing uncertainty with the progression of the early week low. Highs
expected to get to the 40s and 50s Monday through Thursday with lows
mainly 30s, possibly 40s Monday night.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 515 PM CST Thu Jan 12 2017

High pressure to our northwest has helped to filter in some
drier air in the low levels and as a result, has pushed the
clearing line to Peoria this hour and we expect that trend to
continue this evening, with the remainder of the TAF sites
improving to VFR by 04z. Other than some sct-bkn mid and high
level clouds into Friday, VFR conditions should prevail through
the end of this forecast period. The next threat for freezing rain
should begin to spread back north after 21z tomorrow afternoon but
still remain just south of SPI and DEC for this forecast period.
Surface winds will be from the northwest to north at 5 to 10 kts
tonight and then shift into the northeast on Friday with speeds in
the 8 to 13 kt range.


Winter Storm Watch from Friday afternoon through Sunday morning
for ILZ042>057-061>063-066>068-071>073.

Winter Storm Watch from Friday afternoon through late Sunday
night for ILZ040-041.

Winter Storm Watch from late Saturday night through late Sunday
night for ILZ027>031-036>038.



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