Freezing drizzle began across much of central and northeastern South Dakota during the day on Monday, Dec 12th. By the evening, a glaze of ice had formed on surfaces, up to a tenth of an inch thick. Freezing rain with significant ice accumulations followed into the day Tuesday, Dec 13th, especially across and near the Prairie Coteau where Ice Storm criteria was met (at least a quarter inch of ice). Meanwhile, wet, heavy snow fell further west. The responsible deep low pressure system would only slowly track east over the next several days, leading to round after round of additional snow across the region, sometimes with thunder, with the snow becoming progressively fluffier with time as colder air moved in on the backside. Once high winds developed with gusts of 40-60 mph, blizzard conditions developed and persisted for multiple days, finally wrapping up across northeastern SD through the day on Friday, Dec 16th. 

This was a highly impactful, major winter storm due to its severe, widespread and prolonged nature. To make matters worse, impacts were exacerbated as this system lasted through the entire work-week. Nearly the entire state was under an SDDOT "No Travel Advised" or had road closures by Thursday, as numerous roads became impassable. I90 closed from Chamberlain to Rapid City from 10am CST on Tue Dec 13th through mid-day Sat Dec 17th (from Kadoka to Chamberlain), and I29 closed from Watertown to the ND border from 7pm Wed Dec 14th through 9am Sat Dec 17th. Additionally, multiple consecutive days of school was cancelled, tree damage and power outages resulted (over a thousand at any given time for multiple days across the area), the KDLO transmitter tower near Garden City collapsed from the ice, and several dozens of semi drivers were stranded for several days and nights at the Coffee Cup Fuel Stop in Vivian. Numerous other vehicle accidents occurred as well.