Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 251945

Area Forecast Discussion
National Weather Service Lincoln IL
245 PM CDT SUN SEP 25 2016

.SHORT TERM...(This evening through Monday)
ISSUED AT 245 PM CDT Sun Sep 25 2016

Scattered showers and isolated thunderstorms were east of a Peoria
to Lincoln to Taylorville line at mid afternoon and tracking
northeast ahead of a prefrontal trof moving into central IL.
Scattered to broken cumulus and mid level clouds was giving partly
to mostly cloudy skies. Temps had warmed back into the mid 80s to
around 90F except in rain cooled areas that slipped toward 80F.
Dewpoints ranged from 62-70F so another very warm and rather muggy
summerlike day. A strong cold front over far eastern IA into eastern
MO will sweep east across IL during late afternoon and evening,
reaching the IN/IL border by midnight. Hi-res models show scattered
convection along and ahead of the cold front into this evening. A
strong upper level trof over the upper Midwest will settle east into
the western Great Lakes and IL by sunrise Monday and keep chances of
showers going overnight especially east of the IL river. Lingered
small chances of convection along and southeast of a Danville to
Effingham line Monday morning and should be dry there too by late
Monday morning as clouds decrease over southeast IL and skies become
sunny by Monday afternoon. Lows overnight range from the lower to
middle 50s over the IL river valley, to the lower 60s near the
Wabash river. Much cooler highs Monday of 69-73F with breezy WNW
winds of 10-20 mph and gusts in the 20s.


.LONG TERM...(Monday night through Sunday)
ISSUED AT 245 PM CDT Sun Sep 25 2016

Main concern shifts to the track of the upper low this week. There
is good agreement from Monday night through Wednesday, as the low
tracks from north of Lake Superior to Ohio/Kentucky Wed evening.
Beyond that, solutions diverge. The ECMWF keeps the low just east of
Illinois drifting it south into Tennessee through Friday then
retrograding it to the NW toward IL next weekend. The Canadian and
GFS both slowly drift the upper low toward the East Coast Thursday
into Saturday.

The overall affect on sensible weather will be a slight chance of
showers in NE Vermilion County Tuesday night as all 3 models and the
NAM show the upper low reaching its closest point to our CWA.
Another item of note will be gusty winds on Tuesday as deep layer NW
flow mixes to the surface providing 25-30 mph gusts.

Beyond that, the EC solution would point toward increased rain
chances Wednesday and again next weekend, while the Can/GFS solution
would be mainly dry with increasing temperatures the rest of the
week. The consensus blend shows a continued dry forecast for the
last half of the week and next weekend, and will not alter that
trend with this update.

The chilly air mass will provide below normal temperatures for the
first portion of the extended, with lows in the upper 40s Mon night
and Tues night, and possibly Wed night. High temps Tuesday will be
similar to Monday, in the upper 60s N of I-74 and low 70s elsewhere
in our CWA. Beyond that, it appears we should expect a slow warming
trend of a couple degrees each day for both highs and lows. Even
with that warming, highs will only climb to the mid to upper 70s
next Sunday.


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1258 PM CDT Sun Sep 25 2016

Isolated showers and thunderstorms developed in past hour east of
the IL river to along I-55 and nearing SPI and BMI. The hi-res
models continue to develop scattered convection this afternoon
across central IL and carried showers along with VCTS into mid
evening. A prefrontal trof was moving east into western IL while
cold front was pushing into eastern IA and central MO early this
afternoon. Models push the cold front east toward the IL river by
late afternoon and pass I-57 during mid evening. Still have
chances of showers with upper level trof behind the cold front
tonight and have showers ending at PIA by 07Z and at DEC and CMI
between 10-12Z. Cloud bases are mostly VFR but could get down to
MVFR with convection. Breezy SSW winds 10-15 kts and gusts 15-20
kts this afternoon to turn WNW behind cold front this evening and
gradually diminish to around 10 kts by overnight. Then winds gust
back to 15-20 kts by 15Z Monday with scattered cumulus clouds.


.ILX Watches/Warnings/Advisories...


LONG TERM...Shimon
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