Any rain/ice/snow mix at the onset of precipitation should quickly go to all snow as it all overspreads the area in the 1-4 p.m. time frame Wednesday from southwest to northeast.
Temperatures will cool from 33-38 as the mix completely saturates the dry air, which is a cooling process. This will knock temperatures down to 30-32.
It will be breezy at times tomorrow to tomorrow evening-early night, but wind does not look to be a big issue.
Note line of heavy snow, which is the Arctic front racing southeastward through Illinois tomorrow night.
Behind it, temperatures crash & the winds really crank up with gusts 35-45 mph at times.
Thursday will be windy with widespread blowing & drifting snow with temperatures in free-fall from near 31 in the morning to 11 by evening with wind chills dropping to -12.
Snow will still be falling at frequent intervals throughout the day & it will transition from the wetter snow to a drier, powdery one.
This transition will enhance the blowing & drifting with the northwest to west-northwest winds easily 20-30 mph with periodic gusts of 35-45 mph.
Total snow accumulation Wednesday PM to Thursday night looks to run anywhere from 3 to 6" over much of the area. A bit of very minor ice accumulation is possible, mainly in the south, in the early stages of the event.
I kept the highest amounts confined to the north with 6-9" possible there.
Two things I am toying with:
1. I may end up with 1-3" labeled in the far south if current trends hold. This may or may not occur, I just need more data to make the call.
2. If the 6-9" amounts look to be more isolated, then I will convert the 6-9" band to just "isolated +6" amounts" wording for the northwest. Again, I just need more data to show this to make the call. It may or may not occur.
Friday looks bright, but very cold with highs only 7-14, but the winds will diminish to 3-7 mph, knocking wind chills back down to -7 to 4.
How cold we get Friday night will be determined by how quickly 1040 mb strong Arctic high over the area moves eastward. On its backside, south-southeast wind will commence, resulting in a temperature rise.
With snow pack, calm winds, inversion (warmer, dry lid at 100-300' off the ground) & strong Arctic high with a snowpack, our temperature will crash Friday evening.
We may drop to -20 to -7 over the area. Temperature rise will occur overnight to 6-12 by Saturday morning.
However, with the south-southeast wind increasing, wind chills will run -7 to -3 early Saturday.
With some increasing clouds, winds will crank up in a big way Saturday.
South-southwest winds of 20-35 mph are likely. Widespread blowing & drifting snow is likely. Wind chills will run 0-10 even Saturday afternoon.
We will likely not rise above freezing until AFTER 6 p.m. Saturday evening & reach 37 by around 3 a.m.
This will correspond with peak winds of 25-40 mph.
With these warming temperatures (but lack of sun to not make the melting occur too quickly), the top 0.5 to 1" of snow will see some melting, which will put the kabosh on a lot of blowing & drifting. Instead, this sticky layer with the wind will make for the potential of snow rollers. This is a rare phenomomen where the wind rolls strips of snow up into rolls like insulation. They tend to occur in open areas & vary in size from a soup can to five gallon bucket to even rare, rare instances of them being the size of a oil drum.
It is not guaranteed we will see these, but conditions will be favorable for them. The last time we saw them was 2003.
Spurt of snow/ice Sunday morning should go to some rain before ending as spurt of ice to snow Sunday evening as temperatures fall again.
It is a clipper-type system, so precipitation looks light. If it would track a bit farther southward, we would have a nice little 1-2" snow.
This does not look to be the case. Any snowfall or ice look very minor (dusting) at the onset & at the end.
The high temperature of 47-55 Monday will not occur until around 11 p.m. on Monday night.
The high of 53-59 (I dropped it from 58-63 as front is coming through much quicker) should occur Tuesday morning, then fall, reaching 18-25 Tuesday night.
Between wind chills Friday morning & temperatures early Tuesday, a rise of 70-80 degrees is possible.
Showers are likely late Monday, increasing to steady rain Monday night (isolated rumble or two of thunder) to Tuesday before ending as brief ice/snow.
Winds will be strong Monday-Tuesday from south to southwest, then west to northwest. Gusts 35-45 mph are possible at times.
In terms of rainfall, potential has been there for 1-2" with flooding risk, but trend is to shift heavier rainfall south. We will still monitor.
Late next week looks quite cold, followed by risk of ice & snow by late Friday of next week.