The polar vortex, explained
https://www.youtube.com/watch?v=dvHTFNuwa8U&feature=emb_title
Temperatures in the Midwest are nearing all-time record lows as a powerful polar vortex drives a deep freeze across the eastern half of the United States. The bitter cold will bring below-zero temperatures to a quarter of the continental USA. In fact, it is predicted that Chicago will be colder than Antartica, Siberia, and Mount Everest. Extreme cold, big snowstorms – and even unwelcome invasions from the polar vortex – will continue to hit the U.S., even as humans continue to warm the planet. As he has several times in the past, President Trump again tweeted about global warming during a cold snap: Late Monday, he tweeted that "in the beautiful Midwest, windchill temperatures are reaching minus 60 degrees, the coldest ever recorded...What the hell is going on with Global Warming? Please come back fast, we need you!" However, no matter how much humans have warmed the planet, we still didn't kill winter: Trump's own federal agency – the National Oceanic and Atmospheric Administration – corrected the president on Tuesday, noting that "winter storms don't prove that global warming isn't happening."
How a warmer Arctic could intensify extreme weather
https://www.youtube.com/watch?v=yQliow4ghtU
Some prominent climate researchers think so. That’s because warming temperatures in the Arctic are altering the behavior of the polar jet stream, a high-altitude river of air that drives weather patterns across the globe. As the winds that propel the jet stream weaken, storms, droughts, and extreme heat and cold move over continents at slower rates, meaning bad weather can stick around for longer. Eli Kintisch reports aboard the Norwegian research vessel Helmer Hanssen about how changing conditions at the top of the world could be impacting weather far away.