There will be another aspect to the historic arctic outbreak on Thursday and that is the increasing likelihood of accumulating snow.
The arctic cold front is expected to move into the Four States area around 8 AM to noon on Thursday, and there will be enough moisture accompanying the frigid air mass that accumulating snowfall should occur immediately behind the front. Computer model forecasts may change between today (Tuesday) and the arrival of the cold air on Thursday, but at this time it appears that the Four States area could pick up around 1-3 inches of snow from around 8 AM to 2 PM on Thursday.
Model forecasts still show the greatest snowfall totals are more likely farther north across central Missouri northeast through northern Illinois (pictured below); generally north of interstates 44 and 70. The main aspect of this historic arctic blast into the lower 48 will be the extreme cold air that builds southward behind the front.
Our warmest day in the next seven days will be on Wednesday as we warm up to around 45°F.
Some of the leading edge of the arctic air will be oozing southward into the Four States Wednesday night into Thursday. So, we will start out the day on Thursday around 15°F but by 6 PM, expect temperatures dropping to as low as -2°F.
By Friday morning, the arctic invasion will have reduced our temperature to about -5°F and we will reach a “balmy” 10°F by mid afternoon on Friday. Wind speed will be very strong as this cold air mass moves into the area due to the incredible gradient in pressure from our arctic high to lower pressure associated with the deep surface low that will bring us sufficient lifting to produce our 1-2″ snowfall on Thursday.
Sustained winds around 20-25 mph with gusts to around 45 mph will create dangerous wind chills as low as 30 degrees below zero through Thursday through Friday morning. If you will be traveling longer distances Thursday through the Christmas holiday, make sure your vehicle is running well and that your gas tank is full. These wind chill values are in the dangerous category as exposed skin can freeze in just 15 minutes in these extreme weather conditions. Stay safe. Be prepared as we head into the holiday weekend.