How Will the Polar Vortex Impact Winter in Europe?

Winter is coming, but not anytime soon for Europeans. With an expected warm end to autumn, a warm start to winter is likely. The long-range temperature forecast shows higher than average temperatures across Europe.

The expected weaker La Niña implies that it would be less likely to result in conventional winter impacts, though predictable signals could still influence the forecast guidance.
 

 
However, some influence of a weak La Niña, SST and/or Arctic Sea ice forcing and a northward shifted frontal zone (implying a weaker than normal tropospheric jet stream) can lead to more frequent high latitude high pressure blockings in the eastern North Atlantic, which harbors the risk of colder spells at times including early season cold air outbreaks.

 

How the polar vortex will impact winter

Another crucial factor for boreal winter is the state of the stratospheric polar vortex (SPV). The graph below shows the SVP seems to be stabilizing after a bumpy start, with above-average strength from early November (on average).
 

 
The latter seems reasonable with a strongly positive (i.e., westerly) Quasi-Biennial Oscillation phase and a weaker or shifted Aleutian low. This is due to a retracted Pacific jet stream during La Niña resulting in lower wave activity fluxes into the Arctic stratosphere.

 

The disruption is up in the air for November and December

“Winter is coming, but not anytime soon for Europeans…”
Nevertheless, an increased risk of high latitude high pressure blockings could also increase wave activity fluxes from the well-known regions around the globe (e.g. Alaskan Ridge/far North Pacific or the Northeast Atlantic/Greenland region & northern Ural) high pressure blocks according to climatology, leading to a temporary weaker, or at least, wavier SPV (see graphic above).

On the other hand, a relatively undisturbed and stronger SPV could initiate downward propagation of the westerly wind momentum at some point. This means a greater chance of wetter and milder conditions across western and central Europe.

Parts of Europe are currently favored to have average or even drier than normal, mainly the southern portions of Europe. The U.K., at least northern and western parts of western and central Europe, parts of Scandinavia, far northeast and perhaps far eastern Europe have better chances for above-normal precipitation totals during the period.
 

 
The long-range winter forecast takes into consideration several other factors; the polar vortex is one variable.

The resulting weather patterns have significant implications across multiple sectors, most notably transportation and logistics companies and utilities balancing supply and demand.

 

Want to get additional weather insights? Watch our seasonal outlook series.

 

About the author

Dr. Jens Bonewitz

Dr. Jens Bonewitz is an experienced long-range energy meteorologist at DTN. He consults with utility and renewable energy clients to help plan and prepare for the impact of weather. He combines research and its practical applications to produce meaningful weather forecasts within the S2S range.