How a freak diversion of the jet stream is paralysing the globe with freezing conditions

Daily Mail
"Changes in the jet stream's path can cause massive changes in weather conditions across the globe and may be why Australians are now shivering their way through summer and the current freezing conditions in California. ....And Australians expecting to bask in early summer sun this Christmas are instead shivering as icy gusts sweeping up from the Southern Ocean have blanketed parts of east coast states New South Wales and Victoria with up to four inches of snow. ....Other weather patterns are also causing havoc across the may also be affecting the weather, such as the current in the tropical Pacific Ocean, called La Nina, which is disturbing the jetstream over the north Pacific and North America."