Active weather pattern expected for the last week of December

 

December 2021 will be on for the record books with the unseasonably warm temperatures that have been felt during most of the month.  Saturday's high of 51 degrees was the 11th day this month that the high temperature in Rockford has reached at, or above, 50 degrees.  This sets a new record for the most 50 degree days in December; the previous record was 10 days set back in 1941 and 2015.  While the high Sunday didn't reach 50 degrees, it was another day with above average warmth.

The warmer temperatures have made it fairly hard to see much snow accumulate across northern Illinois and southern Wisconsin, but a little more of an active storm pattern may bring a slightly better chance for at least some light snow later in the week. 

The first of several storm systems that'll impact the region is currently moving through the Midwest and Great Lakes, bringing snow - some of which

will turn heavy across Minnesota and western Wisconsin - and elevated thunderstorms across central Iowa.  The dry atmosphere from earlier in the day Sunday will continue to saturate, eventually leading to a mix of light snow and sleet for a time Sunday evening.  As temperatures warm above freezing both at the surface and aloft, it'll be mostly rain that occurs through the night.  There could even be a few rumbles of thunder.  That system will pass to the east Monday morning leaving more drizzle and fog in its wake.  Some of the fog could become dense during the overnight.

The next low pressure system will move east from the Rockies late Monday night and into the Midwest early Tuesday morning.  Another surge of moisture pulled up ahead of the low will allow precipitation to occur Tuesday morning and early afternoon across northern Illinois and southern Wisconsin.  Temperatures initially Tuesday morning will be below freezing, leading to a period of snow just a little after sunrise.  How long the snow lasts will depend on how quickly temperatures warm above freezing by the afternoon.  Right now it looks like Tuesday could bring at least some minor snow accumulations through Noon before transitioning over to rain during the afternoon.  Following Tuesday's storm, a weaker one is forecast to move through Wednesday night with a few light snow showers possible. 

The last system in the parade of storm systems is a little further away, but is one that does warrant some watching.  This, too, will emerge from the Rockies late Friday night crossing through the Plains before moving somewhere in the Midwest Saturday.  Depending on the track of that low, we could see a better chance for some snow - or at least some type of wintry weather - to kick off the New Year.  Stay tuned for further updates on that storm system.