Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 140446

Area Forecast Discussion
National Weather Service Lincoln IL
1146 PM CDT Fri Oct 13 2017

Issued at 855 PM CDT Fri Oct 13 2017

A frontal zone stretching from north of the Great Lakes through
northern IL and into north TX will become more active tonight with
shower and thunderstorm activity from northern IL southward as a
low level jet strengthens. Currently radar shows showers
beginning to develop from northeast Missouri to Quad Cities and
models suggest this will slowly spread into central IL potentially
as far as Danville, Decatur, and Taylorville by morning, but more
likely remaining farther northwest according to most models. SREF
probabilities are consistent with this idea and close to afternoon
forecast package so no updates on PoPs needed at this time. Light
S-SE winds 5-10 mph overnight will keep temperatures up a bit from
last night, ranging from 57 in Lawrenceville to 63 many areas west
of I-55. No significant updates needed this evening.


.SHORT TERM...(Tonight through Saturday night)
ISSUED AT 305 PM CDT Fri Oct 13 2017

1012 mb surface low pressure over east central KS has a frontal
boundary extending into southeast parts of IA/WI. 1033 mb high
pressure over Nova Scotia Canada ridged sw into the TN river
valley. Southerly flow over IL between these system along with
ample sunshine this afternoon was bringing warmer temperatures in
the mid 70s. Latest models press the front to IA/IL border during
this evening as surface low in east central KS ejects ne into
northern MO. This to develop some convection nw of the IL river
later this evening and early overnight and across northern half
of CWA mainly from I-72 north overnight with likely chances from
Peoria NNW. Lows tonight in the lower 60s west of I-57 and upper
50s from I-57 east.

Frontal boundary will lift back north a bit on Saturday before
pushing back se over central IL during Saturday night. Kept se IL
dry on Saturday while likely to categorical pops over IL river
valley. Highs Saturday range from mid to upper 70s from Peoria
north to the mid 80s south of I-72. Still shy of record highs in
the upper 80s and lower 90s on Oct 14th. Chances of showers and
thunderstorms shifts se with the front during Saturday night. SPC
day2 outlook has marginal risk of severe storms Saturday evening
north of I-72 while slight risk of severe storms nw of the IL
river late Sat afternoon and Sat evening. CAPES elevate to
800-1500 J/kg over western/nw CWA from 4-9 pm on Sat while 0-6 km
wind shear is 45-60 kts to help support slight risk of severe
storms nw CWA. Lows Sat night range from lower 50s over IL river
valley, to 60-65F in southeast IL.

.LONG TERM...(Sunday through Friday)
ISSUED AT 305 PM CDT Fri Oct 13 2017

After cold front exits southeast IL during Sunday morning,
chances of showers se of IL river to diminish later Sunday
morning and breezy nw winds to usher in much cooler air. Highs
Sunday range from upper 50s over IL river valley, to mid 60s in
far southeast IL, so little temp rise there from morning lows.
Quite cool Sunday night with lows in the upper 30s and lower 40s,
and the coolest night of the season for many locations. Could be
some patch frost by dawn Monday in low lying areas northern CWA.
High pressure settling into IL early next week to bring the dry
and cooler weather.

A pleasant stretch of fall weather expected Monday through Friday
with nearby high pressure southeast of IL and storm track staying
well north and south of IL. Highs Monday mostly in the lower 60s,
warm into the upper 60s to near 70F on Tue, lower 70s Wed and low
to mid 70s Thu/Fri. Another seasonably cool night in the lower 40s
Monday night, then moderating thereafter into the mid to upper 40s
Tue night and upper 40s/lower 50s Wed and Thu night and in the low
to mid 50s next Fri night.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1146 PM CDT Fri Oct 13 2017

A frontal boundary extending from Wisconsin into the central
Plains will develop increased shower and thunderstorm activity
tonight as low level flow strengthens. Showers and thunderstorms
will potentially arrive at the central IL terminals ranging from
around 11Z at KPIA to 14Z at KSPI-KDEC-KCMI. Higher chances for
thunderstorms will arrive late in the forecast period as the cold
front approaches from the northwest, and included predominant SHRA
with VCTS starting 00Z at KPIA, 01Z at KBMI-KSPI, and 03Z at
KDEC-KCMI. Primarily VFR conditions are expected through the
period, however isolated MVFR cigs/vsbys are possible in
thunderstorms. Winds S-SE 6-10 kts through the period, except
strong and gusty winds possible in thunderstorms, especially after





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