Wind, snow, lightning forecast to hit the Sierra Nevada this week

A late-season storm is rolling through the Sierra Nevada this week, bringing snowfall, high winds and lightning.

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Although the storm system is expected to target the whole region, the most snow is likely to fall in the central and southern Sierra. From Tuesday through Thursday, up to about 8 inches could stick on the highest peaks, according to the National Weather Service office in Reno.

“Honestly through the end of this week, anyone backpacking, especially on the [Pacific Crest Trail] and the higher trails of the Sierras, should definitely keep in tune with the weather,” Chris Johnston, a National Weather Service meteorologist based in Reno, told SFGATE. “And they should probably stay off the eastern Sierra on Wednesday, Thursday and Friday, so they don’t get caught in this stuff.”

On Tuesday, Mammoth Mountain announced an extension to the season through June 7, celebrating the “cold temps, solid coverage and fresh snow in the forecast this week” in a social media post.

There’s about an 80% chance of at least light precipitation regionwide, as temperatures dip 15 to 20 degrees below the averages for late May. Snow levels could drop to 5,500 feet by Wednesday morning; hover between 6,500 and 7,500 feet from Wednesday through Thursday morning; and then rise up to 8,000 feet by Thursday afternoon.

In Lake Tahoe, forecasters expect a mix of rain and snow flurries. Mount Rose Summit, at 8,911 feet, could get up to 2 inches of snow, while most other main passes in the Tahoe region will get more like an inch.

On Tuesday afternoon, isolated lightning could also arrive as the probability of thunder increases to 30% from Lassen County to the Tahoe basin. Chances of lightning continue through Thursday.

“This is a closed upper low from western British Columbia that’s pretty much going to park itself right over the Reno area until about Friday, and then we’ll start to see warming,” Johnston explained. “It’s one of these lows that got cut off from the main jet stream farther south than it would normally for this time of year. It’s a colder event that’s out of the normal.”

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High-elevation snow can be a concern for hikers and mountain climbers in the Sierra Nevada. Search and rescue organizations warn that snow increases the difficulty of well-known hikes, including Mount Whitney. Over Memorial Day weekend, hikers encountered snow at high elevations in the Tahoe region. At one point, search and rescue responded to calls for help from a mountain biker near Freel Peak who was stranded and disoriented in the snow.

The late-season storm comes after the California Department of Water Resources determined this year’s April 1 snowpack was the second lowest on record. As of May 21, the U.S. Drought Monitor now classifies much of California as abnormally dry with the northernmost part of the state experiencing moderate drought.

“The biggest caveat with all this snow is that we’re in late May, so this stuff can melt pretty fast,” Johnston said.

Although the system will likely bring cooler weather to the Bay Area this week as well, the chances of a drizzle remain low, Roger Gass, a National Weather Service meteorologist based in San Francisco, told SFGATE. 

Julie Brown Davis contributed to this story.