NewsNation meteorologist Dave Fraser predicted up to a foot of snow in the higher foothills and parts of the Colorado mountains. Early Tuesday morning, live video captured snow already starting to fall across Denver.
In the Black Hills of South Dakota, snow could be seen Monday night and into Tuesday morning at Terry Peak Ski Resort near Lead, South Dakota.
The storm will likely break some records in the Mount Rushmore state, according to NewsNation meteorologist Brian Karstens.
Accumulations of 6-12 inches were forecast for higher elevations in the Black Hills.
The Associated Press contributed to this report.