By Tyler Hamilton
Yahoo! News
Severe winter weather left nearly three million customers without power in the U.S., particularly in Texas where a winter storm is bringing heavy snow and freezing temperatures. Oil refineries in the state were forced to shut down and for the first time in history, every single region in Texas was issued a winter storm warning on Sunday.
Cold air associated with the polar vortex is tracking south across North America and is the trigger for this active weather. Some states in the South, including Texas and Oklahoma, are in for some of the coldest weather in several decades and a number of cities could see the lowest temperatures in over a century. Take Oklahoma City for example—temperatures are expected to plunge near -25°C, which would make this the chilliest cold snap in over 100 years.