Ice Storm in South Dakota, December 25, 2016

An intense surface low pressure area moved from northeast Colorado to South Dakota from the 24th through the 26th. This storm was unusually warm for the region for late December and produced record breaking heavy rain along with flooding in some cases. Significant icing occurred across areas at or just below the freezing point, which resulted in widespread tree and power pole and line damage to the area. Some downed branches and trees fell onto homes across the region. This storm also brought high winds along with snow and blizzard conditions to the region. This significant storm resulted in massive power outages, stranded motorists and closed roads.

Ice accumulations were significant across central and northeastern South Dakota with over an inch accumulation for some locations. High winds during this event increased the amount of power pole, line, and tree damage. Those who did not see freezing rain accumulations had to deal with ice as well. The ponding of the heavy rain froze overnight once much colder air moved in. Roads and walkways became treacherous ice rinks and remained as such for many days. There were numerous injuries from slips on the ice, as well as several vehicular accidents and flight cancellations. Livestock was also affected, though most made it through the storm. Dairy operations dealt with frozen drinking water tanks.

Precipitation amounts were very impressive for late December, as the system had near record levels of atmospheric moisture to work with. Rain or freezing rain was the predominant precipitation type for those roughly east of the Missouri River on the 25th. Some of the heaviest rainfall amounts include: 0.82 inches at Sisseton and Summit, 0.99 inches at Eureka, 1.05 inches at Miller, 1.11 inches at Leola, 1.14 inches at Victor, 1.28 inches at Aberdeen, 1.34 inches at Orient, 1.44 inches at Bath, 1.48 inches at Westport and 1.73 inches southwest of Stratford. From this rainfall, ice accumulation amounts ranged from a quarter inch to nearly an inch and a half in places. The highest measured ice accumulation was 1.37 inches about 2 miles east of Summit.

Daily precipitation records were set on the 25th for Mobridge with 1.52 inches, Pierre with 0.92 of an inch, Aberdeen with 1.28 inches, and Sisseton with 0.7 of an inch. Aberdeen and Mobridge also broke records for their wettest December day on record, while Pierre recording their 2nd wettest December day on record. Finally, Mobridge also broke their record for the wettest winter day (December through February) with Aberdeen recording their 3rd wettest winter day on record. In Aberdeen, the heavy rainfall combined with melting snow and ice to produce flooding across several streets, driveways, and garages. No doubt a remarkable amount of moisture for a late December winter storm system. Rare thunderstorms, more indicative of spring than winter, were also widely reported on both the rain and snow side of this system across the area on the 25th.

High winds gusting to over 70 mph impacted the entire region on the 25th and 26th. The combination of snow and ice and high winds snapped or otherwise damaged hundreds of power poles, downed several thousand miles of power lines, damaged several hundred transmission structures and brought many substations down. Many roads were blocked by power lines. Overall, more than one hundred lineman worked to bring the power back.

Twenty-one counties encompassing 30 communities and 3 Indian reservations were impacted. Entire communities, thousands of homes and businesses, and ultimately over 12,000 people went without power. For some, power was not restored for 10 days despite tireless efforts. All power was restored by January 4th, 2017. Water and sewer systems shut down for several days for some communities and emergency shelters were necessary. Deuel, Day, Marshall, Roberts and Grant counties were the hardest hit. County and city governments were overwhelmed by ice accumulations and blizzard conditions and struggled with maintaining accessibility even for emergency traffic. Road conditions deteriorated to the point where it took up to several hours for emergency officials to respond to 911 calls. The storm proved to be fatal when a Walworth County man fell, hit his head and succumbed to the elements on Christmas Day.

National Weather Service operations were impacted as well. The surface observing station in Aberdeen and Mobridge were adversely affected or went completely down during the storm. Additionally, the upper air shelter, which houses weather balloons, was frozen shut and thus inaccessible for the morning launch on the 26th.

Due to widespread significant impacts, the Governor of South Dakota declared a State of Emergency on the 26th which helped facilitate the movement of out-of-state crews to aid with power restoration. There was also a Presidential Disaster Declaration for damage to public property. The total estimated damage was near 8 million dollars for central and northeast South Dakota.