Two regional issues:
1.) With small storms, a 10% change in QPF makes a big difference. <0.1" QPF was forecast but around 0.15 - 0.2" fell so snow was "worse" on the road. We've studied this for about 7 years and found most of the big accident days occur when <6" of snow falls. Some of our fire and DOT folks think that if drivers can still kind of see lane markers, they think the roads are fine and don't adjust their driving habits. But once you get 6"+ the roads and grass are covered and it clicks in people's heads. There was a pivot table buried somewhere on my work PC that shows the number of accident calls in our 911 call center and the snowfall LSR from Sterling over time. Once the 5", 6", 7" reports starting coming in, accidents dropped off fast. We thought it had to do with the time of day, but then realized that we were seeing 7" reports during the height of rush hour.
2.) A lot of DOTs were prepping for the weekend event and lost sight of what was in front of them. Some jurisdictions were focused on prepping for big plowing operations so the trucks that normally would support the brine treatment were swapped over to V-blade or large capacity plows.