I got the picture that this is rare (as in once every couple of decades sort of thing), but not unprecedented.
(And that media is being a bit clickbaity in their "record-setting" claims, as this is generally not breaking any "all-time" records, just the last two or three decades.)
Even though these things are impossible to predict, we know the overall mechanism of
how they occur. The Wikipedia articles on the
polar vortex (which keeps cold arctic air "confined" when strong, and "leaks" cold air south when weak) and
Rossby waves (the polar jet stream being at the boundary of the polar vortex, and is a type of Rossby wave) describe the structure of the phenomenon, with the article on the (polar)
jet stream providing interesting information on the polar jet stream itself, like it being surprisingly high in the atmosphere, at 9 - 12 km high, basically
above the cloud layers.
Still, the complexity is in the details. For example, when a "droplet" of cold air "detaches" from the polar vortex, it is very difficult to predict where it will collide with warmer wetter air causing snowfall. Even in Finland, it is possible (but rare) that the very southernmost Finland has
more snow than the northernmost parts, almost 1000 km north.
The funkiest region weather-wise in Finland is the 100 km or so north from the
Bothnian Bay, where the weather changes from "central Finland" to "northern Finland" (for geographical reasons). I take a roadtrip north-south across Finland a few times each year, and in this region, the difference/change in weather tends to be the biggest.
The funkiest region weather/biome-wise in Fennoscandia, in my opinion, is the trip from Kilpisjärvi (in northwesternmost tip of Finland) northwest to Skibotn in Norway, on the coast of Arctic ocean; only some 50 km or so, but also dropping some 500m in altitude. The Finnish side is decidedly arctic, with few stunted trees and scattered shrubbery (actually dwarf birch, betula nana); with the Norwegian side, quickly tending to lush green forests. It's amazing in the late spring: like literally coming from wintery tundra to summer within the span of an hour. The Google Street View of
traversing E8 northwest towards Norway captures some of it, in case you're into that sort of thing.