Precipitation should overspread the area in the 1-4 p.m. time frame tomorrow.
It may begin as mix of cold rain with sleet & snow. However, it should transition to all snow at a pretty rapid pace as evaporative cooling takes over. This is precipitation falling through the dry air & saturating it, which is a cooling process. So, after highs of 34-38, we should wet-bulb down to 30-32.
Snow will be steady through evening & tomorrow night. It will be a rather heavy, wet snow with temperatures steady at 30-32 all night.
South to southeast winds tomorrow will go east, then northeast to north-northeast tomorrow night & pick up to gusts to 30 mph by early Thursday morning.
Note dark blue line of heavy snow in central Illinois early Thursday morning. That is the Arctic front.
Snow will continue into Thursday, at least periodically. As the Arctic front comes through Thursday morning, it may snow heavily for a bit (line of snow squalls embedded in larger overall area of snow) with gust of wind to 40 mph, leading to greatly reduced visibility.
Following the passage of the front, temperatures will fall from 30-32 to 8-16 by evening with wind chills falling pretty steeply all day.
Snow showers will continue into Thursday evening & taper with time Thursday night.
Total snowfall accumulation Wednesday p.m. to Thursday night should run 3-6" for much of the viewing area. Exception is Kentland to near Rensselaer & northward, where 6-9" is possible.
I'd make totals higher for the viewing area if there wasn't so much heavy rainfall falling south of our area robbing some moisture from us. This system does have a good track for a heavy, significant snowfall here.
I am still toying with the notion of (pending more data to push me in that direction):
1. Replacing the 6-9" in the northwest to "isolated +6" amounts"
2. Putting a 1-3" zone in the far southern areas (along & south of a Darlington to New Market line).
Northwest winds will be strong Thursday overall , sustained at 15-25 mph with gusts easily 30-35 mph. A few gusts may reach up to 45 mph.
This will lead to much blowing & drifting snow with substantial to significant reductions in visibility as the drier, powdery snow on top will be much more agile.
Wind will decrease some Thursday night, but with clearing, lows of -12 to -2 are possible. Winds chills of -30 to -15 are also possible by early Friday morning.
Friday looks bright with less wind, but it will be very cold. Highs should only run 6-13 & there should be enough wind to keep wind chills at -10 to -2.
With a clear sky & a period of very light to calm winds (with a snowpack & inversion) under Arctic surface high, temperatures have the potential to tank Friday evening-early overnight to -20 to -4.
However, temperatures will begin to rise with commencement of south-southeast wind 12 a.m. & onward.
It may still be cold enough (actual air temperature) as the wind kicks in to bring wind chills down to -25 to -15 for a while Friday night.
Saturday should feature increasing clouds with strong winds from the south-southwest increasing to 20-30 mph. After 5-12 at 7 a.m., we will likely not reach above freezing until around 6 p.m. & likely will not hit our high of 36 until around 11:30 p.m.
Blowing & drifting snow will be an issue Saturday.
As we warm Saturday night, south-southwest winds may peak at 25-40 mph. Given a bit of melting in the top 0.5-1" layer of the snow, the blowing & drifting should decrease, but this could give us an opportunity for snow rollers (given the strong winds).
They are not guaranteed, but those are favorable conditions for them.
Winds will blow over that melting thin layer of wetter snow & rather than it drifting, it will roll like a fruit roll-up into soup can to even 5-gallon bucket-sized cylinders.
After peaking at 38 early Sunday morning, it appears that temperatures will fall Sunday afternoon into the 20s with a northwest wind at 15-30 mph.
A few sleet/freezing rain/snow showers to sleet & rain showers are possible Saturday late night to Sunday morning. This looks to be followed by some snow showers Sunday afternoon-evening.
Any accumulation looks localized & amounting to only a dusting.
We will likely not hit our high Monday until 11:59 p.m. that night, as much of the day will be in the 30s to 40 & we will not even get to 45 until perhaps 9 p.m. So, I trimmed that high a bit.
We should hit our highs around 10 a.m. to 1 p.m. Tuesday at 53-59 (only about a 12-hour spring!), then fall to 28-33 by 6 p.m. Rain is likely Monday night-Tuesday in two main rounds, but may end as rain/snow/sleet mix, then snow. Any accumulation looks very minor at this point.
North-northwest wind later Tuesday may gust 30-40 mph.
Potential is there for 1-2" of total rainfall with isolated thunder.
Beyond next Tuesday, it will be much colder. Wednesday & Thursday look bright, but cold with highs in the 20s & lows to the single digits.
Clipper next Friday, February 21, could bring some very minor to minor snowfall with gusty winds turning from the southwest to the northwest.
Another clipper & Arctic front may bring some snow in around early February 23 with gusty west to northwest winds to 40 mph.
Shot of cold, cold air will occur behind it.
Overall, temperatures look to average below normal to the end of February with precipitation averaging above normal.