Galena, Illinois and cities in Iowa, southeast Minnesota, and southwest Wisconsin were under a Blizzard Warning, while the Chicago Area was under a Winter Storm Warning.
A Blizzard Warning is actually a specific extension of a Winter Storm Warning involving blowing snow that decreases visibility.
A Winter Storm Warning involves hazardous winter weather conditions when threats to life and/or property are occurring, imminent or likely. The generic term, winter storm warning, is used for a combination of two or more of the following winter weather events; heavy snow, freezing rain, sleet and strong winds.
A Blizzard Warning is an event-specific warning beyond a Winter Storm Warning that is issued for emphasis of a single weather hazard involving high winds and blowing snow that causes reduced visibility …
Blizzard Warning – Sustained winds or frequent gusts of 35 mph or greater, considerable falling and/or blowing snow reducing visibility frequently to 1/4 mile or less for a period of three hours or more. There are no temperature criteria in the definition of a blizzard but freezing temperatures and 35 mph winds will create sub-zero wind chills.
The other event-specific warnings are Heavy Snow Warning, Ice Storm Warning and Heavy Sleet Warning.
Heavy Snow Warning – Snowfall of 6 inches or more in 12 hours or less, or 8 inches or more in 24 hours or less.
Lake Effect Snow Warning – Lake effect snowfall of 6 inches or more in 12 hours or less, or 8 inches or more in 24 hours or less.
Ice Storm Warning – Accumulations of 1/4 inch or more of freezing rain.
Heavy Sleet Warning
– Accumulations of 1/2 inch or more of sleet.