During a weekend that’s widely known as the unofficial start of summer in California, visitors who trekked to Lake Tahoe for Memorial Day were met with a flurry of snowflakes that turned the landscape into a winter wonderland in May. The storm responsible for the late-season snow in the Sierra Nevada town was one in a series of chilly spring systems that kept temperatures low following a marathon wet winter that filled reservoirs and streams and brought once-dry waterfalls back to life in the region.