Northern Ontario, Minnesota, and some other northern states have experienced previews of winter recently. Temperatures are thankfully recovering to above seasonal levels this weekend, but are likely to return to near average for the next week. After this? Well, it’s the time of the year when predictions for the coming winter are easy to find.
An El Niño for this winter remains elusive. As readers know, warmer than average water in the tropical Pacific Ocean can have a pronounced effect on winter conditions in western and central North , in spite of the vast distance. Generally, the warmer that surface water is, there is less snowfall and temperatures are warmer in this part of the world. Before you start cheering – here is the latest: “The chance of El Niño developing in 2012 has been reduced over the past few weeks. Most models “favour the continuation of borderline ENSO-neutral/ weak El Niño conditions in the Northern Hemisphere for winter 2012-13, with the possibility of strengthening during the next few months”. This translates into – little or no influence from this source. It is important to note that El Niño and La Niña are not the only factors that drive global climate patterns.
My thinking is that the record ice melt in the Arctic will have some carry over into jet stream positioning soon and through much of the winter. Compared to average ice cover in the 1980s, there is an “extra” 4 million square km of open water now. This will add a huge amount of heat to the atmosphere as it freezes. Positions of jet streams are influenced by the temperature difference between the Arctic and areas to the south. Jet streams steer day-to-day weather systems and an “interesting” winter is likely in the offing.