Peoria, Ill. (WMBD) — December has arrived and before we know it Christmas Day will be here. Whether you love it or hate, many people will acknowledge that it’s nice to have a little snow on the ground for Christmas morning. So that begs the question, what are our chances of seeing a white Christmas in Central Illinois?
What is the definition of a white Christmas?
According to the National Weather Service, a Christmas is considered white if there’s at least one inch of snow on the ground. It doesn’t matter if snow is falling or not.
What is the historical probability of a white Christmas?
Based on the new U.S. Climate Normals, which are comprised of data between 1991 and 2020, the historical probability of having at least one inch of snow on the ground ranges from 20-35% for most of Central Illinois.
You can see the historical probabilities for various Central Illinois communities below.
|Location||Historical Probability of 1″ of Snow|
As one might expect, the chances are higher further north with locations along I-80 carrying a 35-40% chance. The last time Peoria had a white Christmas was in 2017 when there was 3 inches of snow on the ground. NOAA has a higher resolution and interactive version of the map below which you can view here.
How are things looking this year?
As I discussed in an article I wrote last week, a blocking high over Greenland and an upper-level ridge over Alaska would lead to a series of events that would steer colder temperatures into the eastern U.S. in the coming weeks. It looks like that pattern could take shape around the middle of December.
The high pressure system currently over Greenland is poised to retrograde (move west) over the next week leaving above average temperatures over eastern Canada. As a result, below normal temperatures over western Canada would drop southeast and blast areas along and east of the Rockies, remaining in place through the end of December.
You can see this reflected in the loop below which reflects the EPS model 850 mb temperature anomaly over the next couple of weeks. Notice how temperatures are generally near to above average at the start of the loop but then more persistent cold develops around December 14th across the United States while warmer temperatures stay over eastern Canada.
With negative phases of the Arctic Oscillation, North Atlantic Oscillation, and the Eastern Pacific Oscillation in place, a large scale trough is likely to be in place over the eastern U.S. with ridging in the west. This type of pattern not only favors colder temperatures over Central Illinois, but could also bring more opportunities for snowfall.
You can see this reflected in NOAA’s 3-4 week temperature and precipitation outlook which calls for below average temperatures and near to above average precipitation between December 17th and December 30th.
While certainly not a guarantee, the way things are looking as of this writing, I’d say Central Illinois’ chance of experiencing a white Christmas in 2022 is a little better than the historical probability of 31%. If you’re a white Christmas fan, I think you should feel a bit optimistic about our chances this year.