Not all precipitation is created equal, as springtime in California frequently reminds us.
A record March heatwave was the driving force behind a rapid snow melt in the high Sierra. It also led to sharp declines in the amount of liquid water contained in the snow.
Last weekend’s storm delivered 42 inches of snow at upper elevations, reports the UC Berkeley Central Sierra Snow Lab.
The snow pack in the central sierra was only 27 percent of normal as of April 13, according to the California Cooperative Snow Surveys Program.
Snow at higher elevations this week may help, but it probably won’t be nearly enough to make much of a difference.
The snow pack likely peaked in late February or early March and has dropped 40 percent since then, said Rachel Hallnan, a hydrologist with Yosemite National Park who is based in El Portal.
The Merced River appears to have reached its season peak on March 21, as measured at Pohono Bridge on the west end of Yosemite Valley.
If that remains the high point, it would be by far the earliest recorded peak on the Merced River in Yosemite Valley, surpassing a record set in 1939, a full month later.
“While small weather systems in early April offer some brief relief, the March heatwave, rapid snow pack loss and early runoff are exceptional in Yosemite’s historical record,” Hallnan said last week.
Yosemite National Park Superintendent Ray McPadden said the heat wave means visitor access to Glacier Point and Tioga Road could be two to three weeks ahead of schedule.
He declined to offer a specific date, but noted the general target date is Memorial Day on May 25.
“I think we’re going to be many weeks ahead of that this year,” McPadden said.
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