An early season winter storm will impacts parts of the northern Plains and Upper Midwest later this week, bringing several inches of snow across the northern tier of the country. Winter Storm Watches, Winter Storm Warnings and Winter Weather Advisories have already been issued for the northern Rockies, likely expanding further east within the next day or two.
Strong low pressure will develop late Tuesday into Wednesday afternoon, quickly lifting northeast into the Upper Midwest by Thursday and then Upper Great Lakes Friday and Saturday. As the low pressure system deepens, it will pull down an unseasonably cold air mass. On the warmer side of the low rain and storms can be expected (including for us in northern Illinois and southern Wisconsin Thursday and Friday). Behind the low, however, heavy snow will fall causing significant impacts to travel, as well as to agriculture. Isolated locations could receive over a foot of snow by the end of the week. Combine that with a strong wind and some places may even experience near blizzard-like conditions.
By the time the cold front arrives into northern Illinois Friday evening most of the moisture will be gone, but the cold will stick around. Temperatures will tumble quite a bit from the mid and upper 60s early in the day Friday, down into the mid 30s Friday night and Saturday. No snow is expected for us, but a few wind-driven showers are possible during the afternoon Saturday.