You left out the higher entity that takes away a significant portion of the snow that was accumulated at regular intervals. It doesn't need to ruin the metapho

You left out the higher entity that takes away a significant portion of the snow that was accumulated at regular intervals. It doesn't need to ruin the metaphor, though: The sun could do that job. It could also explain the fact that the portion that's taken differs depending on where on earth you are creating the snowball.