Extreme weather threat predicted for US following deadly tornadoes

"Another historical weather day is forecast on Wednesday with two never before seen outlooks issued," the National Weather Service (NWS) tweeted. 

"The Central US has never seen a December storm like this," tweeted Meteorologist Bill Karins. 

"Multi-hazard, life-threatening weather on Wednesday." 

From New Mexico to Michigan, more than 36 million people are under high-wind warnings. The winds, which have already reached 70 to 100-plus mph, are expected to damage structures, topple trees and cause many thousands of power outages, according to The Washington Post. 

The system that has already been responsible for several feet of snow, as well as hurricane-force wind gusts in the West, now has its sights set on the Plains and Upper Midwest. More than 20 million people could experience severe weather, reported CNN. 

The threat of severe thunderstorms is historically high in the zone from central Iowa to southeast Minnesota. The NWS Storm Prediction Center has declared a level 4 out of 5 risk for severe storms, and it warns of the possibility of "at least a few tornadoes." 

The Weather Service has never issued such a risk forecast at this level in this area during December. If tornadoes strike Minnesota and parts of northern Iowa, it will be a first. 

"The threat appears to be unprecedented for this region this late in the year," the Center wrote. 

Widespread wind gusts of 60-75 mph and tornadoes are forecast. A derecho, or widespread damaging wind event, is possible this afternoon and evening with "embedded gusts of 80-100 mph," the prediction center warned. 

The most dangerous time frame will occur from late Wednesday afternoon through sunset and could include nighttime tornadoes. Like the tornado outbreak on Friday and Saturday of last week, much of the activity is expected after dark, when tornadoes are 2.5 times more deadly, Xinhua news agency reported. 

Last weekend, over 30 tornadoes ripped through six states in the central part of the US, killing 90 people so far, mostly in Kentucky.