Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 182103
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
ISSUED BY NATIONAL WEATHER SERVICE CHICAGO IL
303 PM CST Tue Nov 18 2014

.SHORT TERM...(Tonight)
ISSUED AT 303 PM CST TUE NOV 18 2014

Cloud cover became a bit more extensive this afternoon but is
starting to dissipate across western IL and expect this trend to
continue this evening but did maintain a chance of flurries for a
few hours. As clouds begin to scatter diurnally...clouds from the
next system will be streaming in from the northwest. Thus...skies
will become mostly cloudy overnight. Flow turns southerly
overnight ahead of an approaching cold front which should maintain
steady or perhaps even rising temps. A short period of light snow
is possible with this front...but should remain mainly north of
the cwa.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 303 PM CST TUE NOV 18 2014

The cold front will move across the cwa Wednesday morning with
light snow expected to remain generally north of the cwa...but
flurries across the northern/central cwa through early afternoon.
As another surge of colder air moves into the area...temps will
be falling in the afternoon with increasing winds in the morning
with gusts 30-35 mph possible for much of the afternoon.

Temps slowly begin to moderate Thursday and Friday...back into the
upper 20s and lower 30s...but with snow cover over much of the
area and sub freezing temps for several days...the ground will
remain cold which will limit temp rises. This may become important
later Friday afternoon and especially Friday evening. A weak ridge
will move across the area Thursday night into Friday morning. The
light winds and clear skies will likely allow temps to radiate
well with lows back in the teens by Friday morning.

The pattern will shift and much warmer air will spread back
across the area Friday night into Saturday. As noted above...as it
does...the low levels and ground temps will likely remain at or
below freezing Friday evening...with temps slowly rising above
freezing overnight. How much qpf will be falling during this time
period is a bit uncertain...but any amount into subfreezing temps
will be problematic. So at this point...have included light
freezing rain for all but the southern cwa Friday evening. If
precip arrives later...then it will likely be more liquid...if it
arrives sooner...then there could be icing concerns over much of
the cwa.

Temps and dewpoints surge into the 40s on Saturday with a period
of rain expected and then as the main surface low approaches later
Saturday night and Sunday...periods of rain along with at least
the chance of thunder will continue Saturday night and Sunday.
High temperatures on Sunday may reach the mid to upper 50s across
the southern third of the cwa.

The low will move across the upper lakes Sunday night with another
strong cold front reaching the area Monday morning. Precipitation
ahead of this front should be all liquid but may mix with or
change to snow as it ends as the colder air spreads into the area.
Strong/gusty westerly winds will continue early next week with
this next surge of cold air.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 1143 AM CST TUE NOV 18 2014

A weather pattern more reflective of winter will continue through
the TAF period. Very cold air aloft has supported the blossoming
of broken to overcast 2500-4000 ft ceilings that should continue
this afternoon. While depths of clouds are shallow they are
collocated within the favored snowflake growth area and light
snow showers have been observed. These are most favored through
mid-afternoon near BMI...CMI...and DEC. Low clouds should
diminish considerably soon after sundown and winds should back and
lessen in speed this evening as well.

The next quick-moving clipper-like system will dive into northern
Illinois early Wednesday morning. As is common with these
systems...a southwest low-level jet should increase in speed in
advance of this. With that being overnight and
decoupling...especially over snow-covered airfields...there could
be modest low-level wind shear through sunrise on Wednesday. As
the disturbance reinforces the cold air and saturation
aloft...flurries/light snow showers and MVFR ceilings will
likely be supported Wednesday morning...especially for locations
along and north of the I-74 corridor.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...CMS/LOT
LONG TERM...CMS/LOT
AVIATION...MTF/LOT





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