A rather robust low pressure storm system will slam into the West Coast this Thursday, bringing heavy rain and snow in addition to gusty winds of 40+ mph to parts of the region. Our main focus will be on California, not only because that’s where the low will make “landfall” but because there is the concern for flash flooding and landslides where the burn scars are from some of the more recent wildfires. That includes in Northern California where the most deadly and destructive Camp Fire occurred. While the rain is needed, too much may cause issues.
This morning, bands of moderate to heavy rain have been swinging onshore into parts of California, Oregon, and Nevada. These on and off rounds of rain will persist through the evening hours of Thursday as the precipitation expands into Southwest and parts of the Rocky Mountains. Rainfall will be elevation dependent, ranging from less than 1 inch in the valleys while over 4 inches may fall in the higher elevations.
Meanwhile in many of the mountains, the precipitation will transition from rain to snow Thursday morning across much of the Sierra Nevada. This snow will be heavy but also very welcome, aiding in the snow pack the state relies on during the drier months. The best risk for heavy snow will be Thursday afternoon and evening before the storm starts to weaken as it runs into the mountains of the West, bringing a round of snow to much of the region. Snow will also be possible in Southern California Thursday night as cooler air allows for snow to fall with levels down to 6000 feet. Several feet of snow is forecast to accumulate in the Sierra, and some locations may even receive over 4 feet.
Beyond this storm, a second but weaker storm will move in Friday into Saturday, the thankfully the precipitation will be lighter.