CINCINNATI -- If this recent cold spell left you shivering, just think: It could've been much worse.
Much, much worse.
We're not talking about the winters of 1977 and 1978, either.
No, let's go back to Nov. 11, 1911. In a single day, temperatures plunged from a high of 70 degrees to a bone-chilling 17 degrees, as a strong cold front moved across huge swaths of the central United States.
For people in Oklahoma City, the dip was even more dramatic: the date's record high of 83 and low of 17 were set the same day. They haven't been broken since.
"In Chicago, one man was overcome by heat and two others froze to death within a 24-hour period," according to the National Weather Service.
The dramatic cold snap came to be known as The Great Blue Norther of 1911.
It also brought several tornadoes and blizzard-like conditions across the nation.
The most intense was an F4 tornado in Janesville, Wisconsin, on Nov. 11. Nine people died. It struck not longer before blizzard conditions later that night.
That phenomenon -- a tornado, then snow -- repeated itself in many other places around the Midwest.
So how'd it happen?
The National Weather Service office in Norman, Oklahoma explains:
"It began with a Canadian high pressure system that began to build over Alberta as early as November 9th. A low pressure system began to organize over the Rockies on the 10th and moved east into Iowa and Missouri on the 11th. Unseasonably warm air was drawn northward ahead of the low on the 11th, while in its wake, cold air plunged south across the entire central United States.
"The unseasonably cold air eventually overspread the entire eastern United States as well, routinely dropping temperatures 30 to 70 degrees in a matter of hours."
While "Blue Norther" is the name given to this system, frigid winds blowing south across the Plains are sometimes known as "the Barber" and "the Arctic Screamer."