Snowball

One of my nieces was in London when it snowed recently - snowed a lot for London apparently. And she showed the locals how to make a snowman. They didn't know about rolling a small ball into a big ball in wet "packing" snow.

It made me reflect on the idiomatic verb, snowball:

Increase rapidly in size, intensity, or importance - the campaign was snowballing

The visual is of a snowball rolling along getting bigger and bigger.

But if you live somewhere warm
and have never seen a giant snowball form...
the metaphor will be lame,
its impact not the same.

On a tangent, the collected Calvin & Hobbes Snowman Strips.