A ‘Category 5’ winter storm ahead?

Most weather watchers are familiar with using numbered categories to describe hurricane intensity. The Saffir-Simpson Hurricane Wind Scale is still considered the gold standard for assessing hurricane wind severity.

Saffir Simpson gif
Image via NOAA COMET program.

Now, National Oceanic and Atmospheric Administration forecasters are testing a new experimental scale for winter storms.

It's called the Winter Storm Severity Index. The index assesses categories to winter storms based on expected snowfall and other winter weather factors. The basic index categories assess impacts ranging from limited to extreme.

WSSI
NOAA

The categories are mapped to show impact zones on inbound winter storms.

Here's a sample forecast map from this quiet weather day across Minnesota.

MPX_WSII

Historically, Minnesota's famous Category 5 winter storm was the Halloween megastorm in 1991, which dumped 28.4-inches at Minneapolis-St. Paul International Airport. Last April's Dayton's Monkey Blizzard would rate a Category 4. That storm produced 15 to 22-inches of snow in the Twin Cities.

Keep an eye out for Winter Storm Severity Index snowstorm categories in upcoming snow seasons.

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