Area Forecast Discussion
Issued by NWS Central Illinois

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878
FXUS63 KILX 231710
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1110 AM CST Thu Nov 23 2017

.UPDATE...
Issued at 1108 AM CST Thu Nov 23 2017

High pressure ridge axis this morning is along the Ohio River
Valley, resulting in southwesterly winds for Central IL. With the
winds out of the southwest, warmer temperatures are moving into
the region. To that end, have bumped up the highs for today a
degree or two, as much of the region is already well into the 40s.
Other than that, forecast is on track and no major updates are
anticipated this morning.

&&

.SHORT TERM...(Today and tonight)
ISSUED AT 345 AM CST Thu Nov 23 2017

Upper level trof over the Ohio river valley to pull away from IL
during today, as a weak disturbance exits eastern IL during this
morning. Could be some isolated flurries from I-74 ne early this
morning. Otherwise, broken mid level clouds to decrease from west
to east during this morning, with ample sunshine by midday into
early afternoon. A frontal boundary over the upper MS river valley
to wash out as it moves into nw IL by midday. So winds stay SSW
to SW at 5-15 mph during today and increasing amounts of sunshine
to modify temps close to seasonal levels on this Thanksgiving Day,
reaching 45-50F for highs this afternoon.

Nearly zonal upper level flow tonight with weak 1020 mb surface
high pressure ridge over TN/KY/WV to bring fair weather and light
south winds to the area tonight. Lows of 30-35F overnight with
mildest readings from Jacksonville west toward MS river valley.

.LONG TERM...(Friday through Wednesday)
ISSUED AT 345 AM CST Thu Nov 23 2017

The 00Z medium and extended range forecast models generally continue
a dry forecast from Friday through Wednesday except for isolated
light rain showers se of I-70 on Tuesday evening with passage of a
cold front. A 980 mb surface low pressure moves east toward
southern James Bay Canada by sunset Friday, then pulls a cold
front se through CWA during Friday night. Moisture and lift
continue to be focused ne of CWA so will keep a dry forecast
Friday night. Breezy ssw winds on Friday ahead of approaching cold
front warm temps into the 55-65F range, warmest from Springfield
sw. Large surface high pressure then settles into the central
plains on Saturday and over the mid MS river valley on Sunday.
Cooler highs Saturday of 50-55F and mid 40s to lower 50s on
Sunday. Models have been trending not as cool over the weekend as
upper level trof and associated colder airmass is focused more ne
of area.

Upper level ridge building over the Rockies on Sunday, shifts
eastward into the MS river valley on Monday, and into the
Southeast States on Tuesday, as surface high pressure slips off
the mid Atlantic coast. Temperatures to modify again during
Mon/Tue, with highs Mon and Tue in the mid 50s to around 60F. The
GFS and ECMWF models show some differences with handling next
weather system during middle of next week. GFS is quicker than
ECMWF with cold front moving se over area on Tue while ECMWF is
moving cold front thru during Tue night into Wed morning. GEM and
GFS models have a band of qpf over se IL late Tue while ECMWF
model is dry until Wed night with short wave trof moving into the
mid MS river valley, and east of IL over Ohio river valley next
Thu. Due to differences between models and from previous runs,
stayed close to consensus for pops during middle of next week.
Have slight chance of showers in southeast IL Tue evening and then
20-30% pops of showers Wed night, and mixing in with light snow
by overnight Wednesday night especially north of I-70. Highs
Wed/Thu are in the mid to upper 40s, with southeast IL near 50F.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 559 AM CST Thu Nov 23 2017

VFR conditions and dry weather will prevail across the central IL
airports through 12Z/6 am Friday, with nearby high pressure from
Texas ne across the OH/TN river valleys. Broken mid level clouds
with bases of 8-12k ft will scatter out at PIA between 12-13Z,
along I-55 by 14Z and DEC and CMI between 15-16Z. A batch of
cirrus clouds over IA and sw WI will track se into central IL by
midday into the afternoon and will see scattered to broken at 25k
ft. SSW winds near 10 kts early this morning will become SW during
the morning and weaken to 5-10 kts during the afternoon. Fair
skies expected tonight with south winds around 5 kts as high
pressure stays southeast of IL.


&&

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

$$

UPDATE...HJS
SHORT TERM...07
LONG TERM...07
AVIATION...07



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