Urban people on the highway, and you have icing and a blizzard where normally not, and it it a very bad thing.
Being a countryside Icelander, I've seen just about everything in the terms of bad weather. I managed to burn down a car engine on a distance less then a mile, since the snow input filled the engine room, melted, froze, and ripped the fan belt! In that weather, the only thing you could have done was to dig in.
In 2000 (february or march) we had a volcanic eruption close to the capital. The weather was dicey, but just about any idiot on wheels decided to have a look. The result was a catastrophy, if I recall correctly there were 1.400 abandoned cars on a certain (bad) leg of the main road. Due to the incredible effort of the resque squads, nobody died.
1.400 cars out of maybe 100.000 on the whole island is....well, 1.4%