Transcript for Mountain West Preparing for 1st Snowstorm of Season
That first major blizzard set to hit, and the snowstorm already turning deadly. A difficult come mute on the roads in Wyoming. Nine states, in fact, from Utah to Minnesota, in the storm's path, as the system moves east. At least one person killed in this pileup on interstate 70 near Denver. And it was near Denver, temperatures dropped from 80 degrees one day to the 20s and 30s the next. ABC's Clayton Sandell from Colorado. Reporter: Tonight, this winter storm is moving fast, but drivers are not. In Wyoming, cars spinning, sliding and stalling in dangerously heavy snow that's bringing branches down on power lines. In the mountains west of Denver, state troopers are investigating deadly crashes on snowy roads. E major pileup of cars and trucks clogging the interstate. Chains are now mandatory. It's pretty slippery. And it's pretty dangerous out here. Reporter: The storm is now shoving aside an unusually warm fall. It was golfing weather yesterday in Lincoln, Nebraska. Yesterday, Denver was record hot, 08 degrees. But today, it's only 34 degrees. A 46-degree drop in just 24 hours. In Denver, the snow is arriving about a month later than Normal. And Dave, we're standing in the middle of interstate 70, just west of Denver here. We understand there's a 20-car pileup just ahead, but right now, this major interstate is completely shut down. David? Wow, the pictures bring it back and quickly. Clayton, thank you. Let's get right to ginger zee, live along the west side highway tonight who is tracking the system. Danger? Reporter: David, chilly and breezy here, but this is down right tropical compared to what's happening in the rockies and northern plains. Let's look at the maps. Winter storm warnings and advisories. That blizzard warning in north Dakota and South Dakota, that means not just snow, in the order of six-plus inches, but wind. 40 to 50-mile-per-hour gusts will come along with this. They are asking that you do not travel. And the real crunch time is the next 24 hours. So, let's pay attention then to how cold it gets behind. You mentioned so many of the item fra sure drops. Dodge city was 87 yesterday. 20 is what it will feel like by tomorrow morning. David? Incredible swing. Ginger zee, thanks. We move on now, to those
This transcript has been automatically generated and may not be 100% accurate.