Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 160930

Area Forecast Discussion
National Weather Service Lincoln IL
330 AM CST Sat Dec 16 2017

.SHORT TERM...(Today and tonight)
ISSUED AT 330 AM CST Sat Dec 16 2017

Breezy and much warmer conditions will be the rule
southwesterly winds increase ahead of the next slowly approaching
cold front. A band of mid-level clouds currently along/north of
the I-74 corridor will quickly lift northward early this morning,
leaving behind mostly sunny skies across the entire KILX CWA for
the balance of the day. Despite full sunshine and brisk
southwesterly winds, warming will be mitigated somewhat by shallow
mixing. Forecast soundings suggest mixing will only take place up
to about 900-950mb, which would yield afternoon high temperatures
in the upper 40s and lower 50s. Skies will remain clear this
evening before clouds rapidly increase from south to north across
the area after midnight as a short-wave trough approaches from the
southwest. Low temperatures will be in the lower to middle 30s.


.LONG TERM...(Sunday through Friday)
ISSUED AT 330 AM CST Sat Dec 16 2017

Precipitation associated with the wave will lift northward tonight
and will be poised just S/SW of the CWA by 12z Sun. Forecast
soundings are initially quite dry, so have delayed the onset of
precip by about 3 hours...with areas along/north of I-74 remaining
dry until the 15z-18z time period. Given the delayed arrival and
the resulting boundary layer warming that will take place, most of
the precip will be in the form of light rain...however enough
evaporational cooling may occur to allow for a brief period of
sleet as the precip commences. Any sleet will be very short-lived
as the precip quickly transitions to light rain. The rain will
come to an end by late Sunday afternoon as high temperatures top
out in the lower to middle 40s.

After that, a period of mild and dry weather will be on tap for
much of the extended...before the next significant system arrives
by the end of next week. 00z Dec 16 models are in relatively good
agreement with this system...with the ECMWF being about 6-12 hours
slower than the GFS. At this point, think a cold front will push
into Illinois Thursday afternoon accompanied by rain showers. As
the front passes and colder air trickles into the region, rain
will change to light snow Thursday night into Friday
morning...with some minor accumulation possible. Will need to keep
an eye on later trends...because if the ECMWF verifies, there
will be more rain and less snow than currently forecast.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1118 PM CST Fri Dec 15 2017

Next batch of clouds above 10,000 feet is working its across the
TAF sites, but should be exiting eastward through about 12Z. Have
introduced a mention of LLWS at KPIA/KBMI/KSPI through sunrise, as
a 45-50 knot low level jet punches northeast over the next couple
hours. Some surface gustiness is expected later Saturday morning
as some of this jet mixes to the surface, but winds will subside
by late Saturday afternoon.




LONG TERM...Barnes
AVIATION...Geelhart is the U.S. government's official web portal to all federal, state and local government web resources and services.