The storm begin during the AM rush hour, and hit hard. Plenty of people were already on the road, and plenty more figured they would get where they were going before things got bad.

Also, the storm was late. It was supposed to be overnight, and when it was late I'd bet people figured the weather report was just wrong and there wasn't going to be much snow after all. I know that was my thought when I first woke up in the AM and looked out my window, before I actually checked the weather.

Also, 6-12 inches in 6 hours is a pretty major storm for the DC area. Roads went from wet to impassable in a hurry. The sheer number of accidents combined with the traffic load meant it took a long time for crews to even get to the wrecks, let alone clear them.

And people are morons. They don't check the weather report. They don't believe what they read even when they do. They don't know how to drive in bad weather, and figure their s**t is just more important than everyone else's.