Past content this time of the year has discussed the possible role of Arctic-region sea ice changes and winter weather across parts of North America. Before we dig into current conditions, let’s review some statistics and the latest winter forecast.
The following image show temperature rankings for last winter (December through February). Note that most of the nation experienced either close-to-normal or above-normal temperatures.
However, if we look at the late winter period, in this case, February, we see a much colder pattern.
And here is this winter’s temperature outlook. Be sure to take notice of the unshaded area across much of the Midwest. This outlook calls for the potential for possible intrusions of unusually-cold air into the Northern Plains, Midwest, and Great Lakes regions.
You might remember the discussion on a possible relationship between changes in October Siberian snow cover and subsequent winter temperatures.
As a review, increases in October Siberian snow cover is a primary basis of some, but not all, long-range winter outlooks.
Scientists, including Dr. Judah Cohen, theorize that a low amount of late summer and early fall Arctic ice can result in increased Eurasia snow cover.
The extensive Siberian snow pack can serve as a source of cold air throughout the winter months. Seasonal wobbles of the PV can transport this cold air into parts of the U.S., especially the Northern Plains, Upper Midwest, and Great Lakes regions.
Note the currently-low extend of Arctic sea ice.
The latest Euroasian snow cover observations indicate above-normal coverage. According to the Siberian Snow Cover theory, this might point towards a colder-than-normal winter (especially over the Northern Plains, Upper Midwest, and Great Lakes) and support the NOAA Winter Outlook.
However, recent research indicates that unusual atmospheric circulations patterns simultaneously drive cold mid-latitude winter and mild Arctic conditions, with sea ice loss having minimal influence in severe mid-latitude winters.
Furthermore, this study finds that the same atmospheric circulation patterns that give rise to severe mid-latitude winter weather also serve to transport relatively mild air into parts of the Arctic, reducing ice cover.
Thus, the pattern bringing the unusually-cold weather into parts of the U.S. is also reducing sea ice, rather than the other way around.
Source: Nature Climate Change
And if the medium-range European model proves accurate, the middle of the month is looking very cold.
Current low Arctic sea ice (open water) and above-normal Euroasian snow cover could point towards harsh (especially late) winter temperatures over the Northern Plains, Upper Midwest, and Great Lakes.
However, a recent scientific study indicates that we should not put too much confidence in this (Siberian Sea Ice) theory quite yet with additional research warranted.