Ignoring other climatic factors, like the current La Niña episode (which is weaker than last year’s), there is good reason to assume the US will not have as many outbreaks of cold air and suffer less blizzard conditions during the coming winter months, compared to the winters of recent years.

Recent Nature Geoscience publication shows correlation between sunspot cycle and the AO and NAO index. This in turn influences northern hemisphere temperature distribution. Current NASA observations meanwhile show the 2008-2010 sunspot minimum has come to an end – shown NASA forecast predicts new peak around the year 2013. It is important to note that for the US outbreaks of cold air from the north are also quite strongly related to ENSO – a factor not taken into account here. Full resolution infographic.

The reason Arctic air is less likely to reach the US is because the northern regions are less likely to develop high pressure systems – as a monitored increase in solar activity favours depressions over the pole (which would improve thermal isolation there).

Recent cold US winters occurred during solar minimum

Judging by recently published research this only changes temperature distribution – and does not lead to a net warming. Whereas temperatures in the US should be higher on average than they were last year, especially the northern regions of Canada (and the entire Arctic) should be colder. This may in turn even lead to some extra recovery of Arctic sea ice over the coming winter months.

Research by a group of British scientists, led by the UK Met Office and recently published in Nature Geoscience confirms a (previously suggested) strong connection between solar activity and especially European winter weather – as both climate models and empirical evidence show westerlies around the northern hemisphere decrease when there a few sunspots.

This allows for the formation of high pressure systems to develop over Arctic regions and for cold air outbreaks towards Europe or the USA. At the point where such cold air meets warmer air further south heavy snow storms may develop.

Some Arctic sea ice recovery?

But as recent NASA observations show the number of sunspots is actually rapidly increasing – and working towards a forecast new solar maximum, as can be seen in the infographic. Therefore we seem in for a different scenario for the coming winter – and perhaps as many as 6 consecutive years in total: Arctic depressions. These prevent outbreaks of cold air over land towards the south, which may in turn keep the Arctic itself refrigerated. As a result also large parts of northern Canada and Alaska may experience lower winter temperatures than they have in recent years – and judging by this one factor last winter’s lowest sea ice extent may survive as a record for at least a year [depending on how a positive AO influences the normal winter Arctic thermal inversion].

© Rolf Schuttenhelm | www.bitsofscience.org