Minnesotan here. This is about the 4th time that this has happened.

They have crews that climb up on top and brush shit off. But, after 20"+, it becomes kind of a futile attempt.

They have heating coils to help melt the snow, but it was so cold and there was just too much of it that it didn't work. Apparently, this was part of the problem, as it mainly heated up the dome and it became more flexible than normal, so it started to bend and hit a tipping point.