NEW YORK, Feb. 17 (Xinhua) -- Harsh weather moved west on Monday as a polar vortex was expected to grip the Rockies and the northern Plains after winter storms pummeled the eastern United States over the weekend, killing at least 10 people, including nine victims in Kentucky who died during flooding from heavy rains.
The National Weather Service warned of "life-threatening cold" into Tuesday, with temperatures in northeastern Montana predicted to dip as low as 45 degrees below zero (-42.78 degrees Celsius) with wind chills down to 60 degrees below zero (-51.11 degrees Celsius).
Dangerously cold wind chill temperatures as low as 50 degrees below zero (-45.56 degrees Celsius) were expected in most of North Dakota, which remained under an "extreme cold warning" along with large swaths of South Dakota and Minnesota, The Associated Press cited the weather service.
Meteorologists said several states would experience the 10th and coldest polar vortex event this season. Weather forces in the Arctic are combining to push the chilly air that usually stays near the North Pole into the United States and Europe.
