Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 311159

Area Forecast Discussion
659 AM CDT Fri Oct 31 2014

.SHORT TERM...(Today)

The passage of a strong cold front and upper level shortwave will
highlight the short term forecast. At 08z/3am the front had already
reached near the Illinois River Valley, with the upper wave centered
behind the front across Wisconsin. Very gusty northwest winds were
lagging behind the front by a couple of hours, so winds in our
counties will begin to increase by around sunrise, especially NW of
Lincoln. Wind gusts this afternoon will climb into the 30-40 mph
range, especially east of Peoria to Springfield. Spotty rain showers
or sprinkles were developing just ahead of the front, generally
along and east of the I-55 corridor at 3 am.

Spotty showers will continue to advance eastward with the front
today, then linger this afternoon as the upper level shortwave
affects eastern Illinois. As colder air arrives on brisk northwest
winds today, some of the light rain showers could change over to
snow showers for areas east of Champaign and north of Paris.

Highs today will likely occur this morning, as the colder air and
cloud cover prevent temperatures from rising much this afternoon.
Temps will likely become steady or slowly fall by midday in most


.LONG TERM...(Tonight through Thursday)

A potent Canadian shortwave will dive sse from Lake Superior and WI
across IN/KY tonight. North-northwest winds 20-30 mph with gusts
30-40 mph will diminish to 10-15 mph overnight with gusts up to 20
mph. This will advect in subfreezing temperatures of 25-30F and
bring a killing freeze to much of IL overnight until mid morning
Saturday. Will continue the freezing warning overnight until 9 am
Sat for central and southeast IL. Moisture flow off Lake MI could
bring a few snow showers near the IN border especially over
Vermilion county this evening. A taste of early winter weather for
Halloween Trick or Treaters this evening with wind chills slipping
into the low to mid 20s. Chilly highs in the mid 40s Saturday
despite a fair amount of sunshine, due to north winds 8-15 mph and
gusts 15 to 20 mph over eastern IL.

Strong Canadian high pressure of 1039 mb over ND will settle over IL
Saturday night as it slowly weakens with fair skies and light winds.
This will bring another hard freeze overnight Saturday night and
early Sunday morning with lows in the middle to upper 20s, and
coldest east of I-57. Mostly sunny skies Sunday but still chilly
highs in the upper 40s to around 50F.

More unsettled weather pattern takes shape Monday-Wednesday as IL
gets in a southwesterly upper level flow with upper level ridge
shifting east of IL and strong upper level trof digging into the
southern Rockies. A frontal boundary will set up from the southern
Plains ne into the Ohio river valley Monday night through Wed and
bring increasing chances of showers. Cold front to move se across
central IL Tue when best chances of showers and isolated
thunderstorms will be. Have 20-30% chance of showers by Monday
afternoon west of I-55 as clouds increasing from the west during the
day. Then likely chances of showers develop during Monday night into
Tue and highest pops shift into southeast IL during Tue night and
Wed. Milder highs in the upper 50s and lower 60s Monday and 55-60F
Tue and Wed. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Slight chance of showers in southeast IL Wed
evening, otherwise drier weather is expected Wed night thru Friday
as dry west northwesterly flow trails the system with seasonable
highs still in the mid to upper 50s and near 60F in southeast IL.


.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)

A brief period of MVFR clouds around 2k FT will affect DEC and CMI
through 13-14z before mixing lifts the cloud deck into the VFR
range. Then VFR conditions will prevail the remainder of the TAF
forecast. NW winds will increase early this morning with sustained
20-25kt and gusts to near 40kt at times by 16-17z.

The leading edge of a strong shortwave aloft could trigger a few
rain or snow showers between 14z and 18z for the northern taf
sights of PIA/BMI/CMI. Any snow would melt as it falls. Otherwise,
precipitation should be minimal at all TAF sites over the next 24
hours. Latest HRRR forecast indicates the stratocumulus should
begin to decrease in coverage and affect mainly areas east of I55
by afternoon as subsidence develops in the wake of the upper level
shortwave. Skies should become clear even over eastern areas
after 00z tonight. Surface winds will gradually diminish,
especially the gusts, toward evening with sustained winds of
12-15 kts after 02z.


FREEZE WARNING from Midnight tonight to 9 AM CDT Saturday FOR



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