Storms here do not so much arrive as pile up against the Palmer Divide, and the wettest, heaviest snow of the year often falls in March, when the rest of the country believes winter is finished. Advanced Concepts reads that ridge the way other people read a calendar. Plowing in Castle Rock means knowing which lots drift first, which north-facing walks will glaze over at four in the afternoon, and where to stack the piles so the melt runs off rather than back across the pavement. The hours are odd and the work is mostly unwitnessed. A parking lot that looks as though nothing happened at all is the finished product.