These storms only happen once in a lifetime - and for areas in Illinois, it hasn't happened in the last 70 years. A system with the barometric pressure of a Category 3 hurricane is delivering blizzard like conditions to the Dakotas and a swath of severe weather across the Midwest. Not surprising, since the warmth ahead of this storm is a product of Typhoon Megi that ravaged areas in the West Pacific.
The Storm Prediction Center has placed parts of IL, IN, OH, and KY under high risk for severe weather Tuesday - a designation that only happens a few times per year. The Valley and Highlands are under slight risk for severe weather - mainly damaging winds - for late Tuesday night into Wednesday morning. This would be an overnight threat of severe weather, something that doesn't happen very often.
This storm will rival if not surpass the one that occurred in the 1970's that sank the Edmund Fitzgerald. Storms like the one rolling through the Midwest have so many components - warmth, wind, snow, thunderstorms, cold - everything. That's the reason they're so few and far between and if they do occur, it's only in the fall and spring.
We're calling this a "pattern changing" or "season changing" system because it alters the pattern so much that there's no turning back. I think we'll be fully set into fall after this system moves through, with high temperatures in the low 60's and overnight lows near 40 degrees. Another cold blast is forecast for the end of next week (November 5-ish) which should truly put everyone in the holiday spirit!