Yeah definitely polar vortices can span multiple continents, this 2022 one hit NA and EU.

As for the storms yeah I don’t think there’s anything limiting it to the US, the US is just a highly unique for meteorology. You have stuff like tornado alley which occurs due to cold, dry air heading southeast from the coast, down over and along the rocky mtns that meets warm, moist air from the Gulf of Mexico, leading to the most active tornado zone in the entire world.

So like a buffalo storm is unlikely unless you live somewhere near a ton of water that hasn’t yet frozen over.

But as for the severity of the average storm; they’ll get worse around the world. EU as well.

Those EU heat waves in the summer? Theyrw kind of the reciprocal of what NA got. Could easily be the other way around or a shitty summer AND winter in one year etc.