We have a 'tin' roof over our back porch but at a very low angle - something like 3/12 - so in the winter when we have some warm days, the snow will slide a bit. When it slides, it 'bends' over the edge before it breaks off and comes crashing down on the stunted plants below. This is about average before it breaks off, though have seen it a bit further along if it gets real cold after a warm day. Yes, it does make a big thud when it hits

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