April 11, 2019

The Snow in Minnesota Is Dirty From Blowing Dust in the Southwest

The powerful winter-but-not-really-winter storm cranking across the Plains and Midwest this week is still producing heavy, thunderous bands of snow as the storm starts to wind down and finally lift toward Canada. Many folks noted that the blanket of white was a little more off-white than they're used to. The sprawling storm resulted in such windy conditions in the southwestern United States that the subsequent dust storms traveled across the country and tinted the snow as far north as Minnesota and Wisconsin.

A record-breaking blizzard continued to produce heavy snow on Wednesday night across the northern Plains and Upper Midwest. A significant portion of South Dakota has seen more than two feet of snow from the storm with more to come. That would be an impressive snowfall total at any point in the winter, let alone near the middle of April.

The storm—often called a "bomb cyclone" in the news because it underwent bombogenesis, or rapid strengthening—isn't all about the snow. Folks on the southern end of the storm dealt with raging winds as the storm ramped-up across flat terrain. These strong winds, gusting at times to 60-70 MPH, picked up a ton of dust as they blew over the Chihuahuan Desert.

This lofted dust raced northward through the day on Wednesday and got ingested into the storm system overnight. By Thursday morning, pictures started emerging on social media of tan-tinted "dirty" snow showing up in places like Minnesota and Wisconsin.

Here's some dusty snow near Minneapolis, MN...

...and in Maple Grove, MN...

...and some more in La Crosse, WI...

...and even as far north as Green Bay, WI...

It turns out that the dust wound up accumulating on the falling snowflakes—and even likely serving as the nucleus on which the snowflake could form—once the layer of southwestern air reached the moisture and cold air on the northern side of the system. Airborne particulates like dust get ingested into weather systems all the time, though it usually involves liquid precipitation. It's common to see a dirty rain develop after a major dust storm, volcanic eruption, or wildfires.

[Top Image: RAMMB/CIRA]

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I graduated from the University of South Alabama in 2014 with a degree in political science and a minor in meteorology. I contribute to The Weather Network as a digital writer, and I've written for Forbes, the Washington Post's Capital Weather Gang, Popular Science, Mental Floss, and Gawker's The Vane. My latest book, The Skies Above, is now available. My first book, The Extreme Weather Survival Manual, arrived in October 2015.