In North America, for the first half of this year’s winter, the big news was warm temperatures and lack of snow. Ski resorts were covered in bare dirt, while January temperatures in southern California topped July highs!
Then, out of the blue, Europe got clobbered: Over the past two weeks, temperatures in Eastern Europe have nose-dived to -30 degrees Celsius (-22 degrees Fahrenheit). Blizzards and the bone-chilling cold have resulted in the deaths of over 550 people so far, with rooftop-high snow drifts trapping tens of thousands of villagers in their homes and cutting off access to entire towns. It has even snowed as far south as North Africa. 
NASA climatologist Bill Patzert of the Jet Propulsion Laboratory explains what happened: “A couple of weeks ago, Mother Nature did an about face. The tight polar vortex that had bottled up the cold arctic air in the beginning of winter suddenly weakened. Cold air swept out of Siberia and invaded Europe and the Far East.” Now the vortex is weakening.
With “the AO (Click here for information about Arctic Oscillation) Index going negative,” as an expert or weather-nerd might put it, cold air escapes from that whirlpool and heads southward, resulting in the killing extremes now plaguing the other half of the planet.
