It was undergoing what's called "bombogenesis", on Wednesday afternoon - which means its central pressure has dropped at least 24 millibars in 24 hours.
On March 13 the cyclone began to unleash its fury in Colorado, where some locations saw up to a foot and a half of snow.
The storm system is expected to weaken by Thursday as it moves over the Tennessee River Valley, bringing mostly rain from MI southward to the Gulf Coast and some remaining snow only in the far northern parts of the country, the weather service said.
Travel: The National Weather Service for Salt Lake City said on Wednesday it might be better to wait until Thursday to start traveling. The powerful winds have left over 200,000 Denver area residents without power while Colorado Gov. Jared Polis has activated the Colorado National Guard for search and rescue operations for stranded drivers in the blizzard. Southwest, Frontier and United have canceled flights and more cancellations and delays are possible, DIA said.
The storm will also bring heavy rain to areas of eastern Nebraska, Iowa, Wisconsin and Minnesota that already have a good deal of snow on the ground, the NWS said.
Utility company Xcel Energy said about 130,000 commercial and residential customers in Colorado were without power due to high winds and wet heavy snow. According to Flight Aware, there have been more than 1,000 flight delays within the US and more than 1,400 flights have been canceled.
According to the Weather Prediction Center blizzard warnings cover parts of seven states.
The latest update from the Cheyenne Office of the National Weather Service is now calling for up to two feet of snow in some areas, along with unsafe winds and risky travel conditions.
The snow wasn't falling as much at about 3:40 p.m. but the high winds were creating major visibility problems. CBS Denver reporter Jamie Leary documented how the wind almost blew her - as well as her selfie stick - away when she exited her news van.