A Sierra storm packing winds gusting to nearly 100 mph over the ridge tops blew into western Nevada on Thursday, toppling power lines, snarling traffic at dark stoplights and stirring up dusty, air quality alerts in Reno and Sparks. The storm ahead of a cold front was expected to bring as much as a foot of snow to the upper elevations around Lake Tahoe by Friday morning, 2 to 4 inches at lake level and up to a couple of inches on the valley floors around Reno, the National Weather Service.