Nice explanation by MPX on pulling the trigger for a blizzard warning.
So the Blizzard Warning... There is high confidence given the snow
totals and strength of winds that blizzard conditions will be
observed in our traditional "blizzard alley" from west central to
south central MN, especially late Sunday morning into Sunday night.
For eastern Minnesota into western WI, blizzard purists may argue
that we don`t hit blizzard conditions of a 1/2 mile or less
visibility with wind gusts of 35 mph or more for 3 or more
consecutive hours. This is because the strongest winds will be
lagging the heaviest snow and eastern MN and western WI really need
the heavy falling snow to achieve the visibility requirements of a
Blizzard Warning. However, we are looking at historic snowfall
amounts for a March storm (see climate section), with travel
expected to be crippled across our entire area tonight into Sunday
night. In addition, when the common citizen looks out the window
Sunday morning (ie. not the blizzard purist!), they`ll likely say,
yup, this is one heck of a blizzard. Given the expected high to
extreme impacts, we felt comfortable in pulling the biggest winter
messaging lever we have, the Blizzard Warning. Simply put, travel is
expected to be very dangerous on Sunday and the best way to get the
message across on just how severe this winter storm will be is to go
with Blizzard Warning.