YOSEMITE NATIONAL PARK, Calif. – The calendar still says summer, but winter is coming early to parts of California’s Sierra Nevada this week, including Yosemite National Park.A trough of low pressure off the Pacific Northwest will swing southeast through Northern and Central California from late Sunday into Monday, bringing a pool of cool air and moisture along for the ride.Snow levels will drop to 8,000 feet, likely bringing measurable snow to parts of the Sierra Nevada. A Winter Weather Advisory is in effect for a swath of the mountains, including those inside Yosemite National Park.Tioga Pass and Tuolumne Meadows could see up to 3 inches of snow, with even some measurable snow as low Yosemite’s Badger Pass by Monday afternoon, according to the National Weather Service in Hanford, California. Cooler temperatures and scattered rain showers will push into the lower elevations, bringing a respite from what has been a relentlessly hot summer in the San Joaquin Valley. Highs are expected to drop below 90 degrees.While this initial dollop of mountain snow will taper off by late Monday, another trough of low pressure may bring another blanket of mountain snow in the middle of the week.