It's a little bit of bittersweet nostalgia. It's a brief, happy, holiday themed strip with the main essence of the comic inside, but also a sort of a sad reminder that the main entirety of Moonstuck is actually over and done with.
Now that I think about it, It's a little poetic that the subject itself is snow. It's kinda like the first snow fall of the winter: it's beautiful and exciting and innocent and fills the heart with a sense of remembrance for all the good times of winters past. But then, after a while, the snow begins to fade and melt away, leaving only the memories of what once were behind. It's kinda sad, but at the same time unavoidable. Nothing can ever really last forever.