What it takes for storm to be a blizzard
Now that power is back for most Chicago-area homes and we’ve dug out from the snowstorm that dumped 8.4 inches of snow on Chicago and grounded more than 1,000 flights, it’s started to warm up, but that nightmare of a storm still seems to linger, like the chairs marking dibs on parking spots.
For instance, you might be wondering if you get to call that colossal snowstorm — one on a shortlist of worst November snowstorms of all time (or since 1884) — a blizzard, especially with the rare blizzard warnings issued before the storm hit.
Unless you also work with Andrew Krein at the National Weather Service and are a meteorologist like him, chances are you’re not sure.
Krein says two criteria must be met for a winter storm to be an official blizzard. First, there must have been sustained wind speeds of greater than 35 mph. With wind speeds recorded at 50 mph at the airport in Wheeling, 49 mph in LaSalle and 39 mph at DuPage Airport, we’re halfway to being able to call the storm a blizzard.
Up next, visibility must have been reduced to below 3⁄4 of a mile for a period of no less than three hours. The weather service issued warnings about reduced visibility at the height of the storm, so that’s a no-brainer, right? “No, we didn’t record those conditions for a sustained period of three hours,” Krein said. So, he says, by technical standards, the storm from Sunday into Monday was not a blizzard.
But what about all that snow? The power outages, closed schools and grounded flights? “Snow isn’t actually part of the equation, although of course to meet the visibility reduction, snow would likely need to be falling,” Krein said.
As for the power outages — in total, about 350,000 ComEd customers lost electricity during the storm — and travel disruptions, Krein says, of course, those are important aspects of a storm. The human element and whether everyone made it through all right are what matter most.
“It was technically not a blizzard, but it was certainly an impactful storm,” he said. “I think for a lot of people who went through that, they don’t care what it’s called, they still have no power.”
And meteorologists won’t be angry at those who use the term “blizzard” for last week’s storm. “For what people think about when it comes to the word blizzard, that’s what you picture,” a storm like the one last week, Krein said.