Larry Skane writes from Catonsville to ask: "How does depth of snow compare to depth of water?" The rule of thumb is 10-to-1. That is, a storm wet enough to drop an inch of rain would make 10 inches of snow. But winter storms aren't all alike. From an inch of liquid, a heavy, wet snow may produce just 4 or 5 inches, while dry, powdery snow could pile up 15 inches from the same moisture. Our Feb. 5-6 storm had an 11-to-1 snow-to-liquid ratio. The second storm was 20-to-1.