For drivers, the rare Seattle snowstorm can quickly escalate to a frozen hell, a cruel reminder that our city is built on a series of steep hills and sits at a latitude north of Quebec City. But the same forces that send SUVs spinning into parked Priuses offer a rare opportunity for anyone with a pair of skis or a snowboard and some initiative to engage in urban downhill skiing (and snowboarding). It doesn?t happen often, but when a big storm dips low enough to cover us in a blanket of white, the true potential of all those hills cursed by cyclists and pedestrians can be realized. My home ?slope? is the Counterbalance, a bat-out-of-hell dash down Queen Anne Avenue from Galer down to Roy Street (and beyond). It averages out to a blue run?nothing more than a green at a reasonable pace, but a black for those with a need for speed, as crashes generally involve the cars parked on either side of the street. Assuming you make it to the bottom in one piece, the only downside is a big one: trudging back up the hill in ski boots, just to do it all over again. MICHAEL MAHONEY