More than half of US population awaits Christmas weekend under wind chill alerts

And the snowiest part is yet to come as the perilous winter storm barrels east across the nation.

A developing «bomb cyclone» is set to unload heavy snow and blizzard conditions especially in the Midwest on Thursday and Friday.

The cold air and storm are affecting nearly every state in some way: More than 200 million people coast-to-coast were under winter-weather alerts for snow or icy conditions Thursday evening, the weather service said.

Wind chill alerts are impacting people from the Canadian border to the Mexican border and from Washington state to Florida, with below-zero wind chills recorded as far south as Texas on Thursday morning and expected in the Southeast by Friday.

«Life-threatening wind chills over the Great Plains (will) overspread the eastern half of the nation by Friday,» the Weather Prediction Center said – and wind chills below minus 50 degrees already have been reported in the past two days in parts of Montana, South Dakota and Wyoming.

Some low temperature records were set Thursday morning in the West and South, and in some cases they dropped this week with record-breaking speed: Denver International Airport saw a 37-degree plunge over one hour Wednesday, preliminarily the biggest one-hour drop recorded there, according to the National Weather Service.

The storm is expected to become a «bomb cyclone» – a rapidly strengthening storm that drops a certain amount of pressure within 24 hours – Thursday evening into Friday, reaching the pressure equivalent of a Category 2 hurricane as it moves into the Great Lakes. This could be «a once in a generation type of event,» a forecaster in the weather service’s Buffalo office wrote Tuesday, after noting that kind of strengthening doesn’t often happen in the lower Great Lakes.

Photo: www.bbc.com