By: Ellen Bacca
GRAND RAPIDS, Mich. (WOOD) — Visibility is awful, the lake-effect snow machine is constant and the wind chills are at -20 to -40. So why isn't this a blizzard?
That's the question I've been getting these last few days as the frigid chill of the polar vortex encapsulates West Michigan .
The reason might seem silly to you, but to scientists it is important. In the weather world, we often create threshold values so that we can count how many times it got "that" bad. Nationally, a blizzard is defined as any time you have all three of these:
- Visibility of 1/4 mile or less
- Sustained winds of 35 mph
- Lasting for at least 3 hours
If you don't have even one of these three variables, it doesn't go down in the books as "blizzard." This week's storm has fallen just short of meeting these three key items.
The wind in this week's storm is blowing at sustained speeds of 15 to 25 mph. Because of that, the visibility temporarily improves and we no longer can give it the official blizzard name.
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