Good afternoon everyone! What happened to the 12+ inches of snow we were supposed to get?
This post will be explaining forecasts for the upcoming few days but first I will start off with why we are not receiving a massive amount of snow from this system that was thought as possible earlier this week!
As of early this week, most of Illinois was in the threat of 10+ inches of snow, even some models were showing regions with 20+ inches of snow. Now, I would be surprised if location in Illinois received more than seven inches throughout this whole system. Very high winds (near or at Tropical Storm force) and extreme, polar like cold are still to be expected Thursday Night to Christmas Day. This system was originally supposed to be a much slower system, most of the snow arriving late Thursday and into the night Thursday as the system moved into the upper Ohio River Valley. The system was supposed to occlude, which in short means the system gets wrapped completely by cold air, and usually slows down. Because of this, the system was supposed to slow down over in Indiana and into Michigan, which meant a lot of snow for our region.
Over the last two days, the system has continued to pick up in speed and, although around the same time frame, slows down and occludes across the northern/eastern Great Lakes. Because of this, the main axis of snow will now be around the Great Lakes instead of the Midwest. I have provided a map below showing the main areas affected.
Now onto the actual forecast totals and maps:
Nonetheless, snow is still expected across the Midwest, but generally totals will be 2-6 inches, and 6+ inches to regions north of Illinois. Most of the snow from the 6+ area will fall from tonight to Thursday morning. The lake effect snow will start to occur during Thursday Night and Friday. Below I have a map showing my current forecast with expected totals. This is subject to change:
The heaviest snowfall will occur during Thursday afternoon. The snow will start at around 5/6am in Western IL and will move east throughout the day.
Below are the timings of when the heaviest snow will fall as of now.
Even though we are expected to see minimal amounts, any snow more than a couple inches will be significant. There is a very sharp temperature gradient that will move through Thursday morning across Central Illinois and the winds will pick up through the night Thursday and will peak during Friday. Because of the quick following temps (into single digits by Thursday afternoon, I will have a picture of this gradient below), the snow itself will be light and soft, as opposed to heavier more compact snow with higher temperatures. Because of winds, gusting 45-50mph from Thursday Night (due to very strong pressure gradients) to Saturday Morning, nearly blizzard conditions ARE LIKELY. It is suggested to stay in if possible at least on Friday. No new accumulating will occur with the winds but with the light snow, the snow will be blowing very rapidly throughout this period.
HRRR at 11am Thursday, showing the 30-35 degree temperature gradient which will move east throughout the day on Thursday and strong, 20-25 kt northwest winds.
Along with the wind, significant cold will spread throughout the Midwest Thursday and into Thursday Night. Below 0 temperatures are expected as lows Thursday, Friday, and Saturday Nights throughout most of Illinois, with the coldest Wind Chills on Friday morning, then Saturday, then Sunday. The winds should gradually become lower and by Christmas Day the winds will be minimal, but wind chills WILL STILL BE below freezing on Christmas Morning.
I did not want to make a map but for each region here is a general wind chill forecast for each region of the state:
Friday Morning: -25 to -40
Saturday Morning: -15 to -30
Sunday Morning: -10 to -25
Friday Morning: -20 to -35
Saturday Morning: -10 to -25
Sunday Morning: -5 to -20
Friday Morning: -15 to -30
Saturday Morning: -5 to -15
Sunday Morning: 0 to -10
NAM Wind Chills at 6am on Friday
HRRR Wind Chills at 6am on Friday
Thanks for reading. Happy Holidays to everyone and stay safe. I will post if there are any major updates!