As snow falls in some parts of the country, it's creating dangerous conditions.
A new video shows a massive avalanche in Utah slamming into a group of snow mobiles.
Thankfully everyone survived. But, in the last week 15 people have been killed in avalanches.
The most in one week in more than a century.
Experts say avalanches are happening more often because the underlying snow that fell a few months ago is really weak now, making it easier to trigger an avalanche.