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…

@NWSTwinCities Dirt or “snirt” (Lakeville)? The latest morning round of snow has a distinct brownish/tan color. Any reports of dust/soil being kicked up by storm winds in Iowa or Nebraska? pic.twitter.com/3jKOprvDjN

— Tim Lundahl (@timmyminnesota) April 11, 2019

…and in Maple Grove, MN…

No need to adjust your screens, that is a mix of red and white snow with the red snow being thanks to the dust from Texas right here in Maple Grove, MN! #txwx #mnwx @NWSTwinCities @NWSAmarillo pic.twitter.com/PCRfvUaEe2

— John Wetter (@johnwetter) April 11, 2019

…and some more in La Crosse, WI…

We have some of your soil here at the office if you want it back @NWSAmarillo #wiwx ❄️ pic.twitter.com/jMbq01MsZ2

— NWS La Crosse (@NWSLaCrosse) April 11, 2019

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

A layer of dirty snow fell earlier today during our snowstorm. Plains dust/dirt ingested into the cyclone? #wiwx pic.twitter.com/Tu7eKy1PFv

— Jeff Last (@JeffLast) April 11, 2019

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]