What is the criteria for a Blizzard Warning?

For those working with the NWS, what the minimum criteria is to warrant issuing a Blizzard Warning?|||Sustained or frequent winds of 35 mph or higher with considerable falling and/or blowing snow that frequently reduces visibility to 1/4 of a mile or less. These conditions are expected to prevail for a minimum of 3 hours. Note that the AMOUNT of snow isn't an issue.|||lots of snow falling and wind blowing