Forecasters are warning motorists that a combination of powdery snow and strong winds could result in near zero visibility tonight and Thursday morning.A second storm is expected to arrive on Thursday morning, bringing more snow and strong winds to the Sierra.According to the National Weather Service, the storm warning remains in effect until noon Thursday. The heaviest snowfall at Lake Tahoe is expected through 8 p.m. today and 6-10 a.m. Thursday.Accumulations of 10-18 inches of snow is expected above 7,000 feet with up to a foot possible below that elevation.Winds tonight are expected to be 20-30 mph, gusting to 50 …