Biggest Sierra snow span in more than a half-century

The unending bumper crop of winter snow is now bumping up against safety and the snowpack could pack a punch for spring flooding. We haven't seen his kind of snow since Nixon was in the White House.

Around 7 p.m. Tuesday, a huge, 200-foot wide, 25-foot tall avalanche hit a three-story apartment building in Olympic Valley near Palisades Ski Resort. It buried two floors.  Fortunately, there were no casualties.

Maz Szabo was in the building next door. 

"It slid down the mountain on the other side of the Palisades Lodge or the Squaw Valley Lodge. There are a bunch of condos back there and older apartments," said Szabo. 

"We've had high avalanche danger for the past several days and today's forecast is 'considerable' which is a step below," said David Reichel, director of the Sierra Avalanche Center.

At the Sugar Bowl resort, a picture of a wall of snow 20 feet deep spoke a thousand words. 

"I had to slide down a slide to get to the door. There was a little air hole there, then dug it out and got in," said Sugar Bowl Marketing Director Jon Slaughter.

PREVIOUS COVERAGE: Avalanche strikes Northern California's Olympic Valley

UC Berkeley's Sierra Snow Lab reports that California is experiencing the snowiest October through February since 1970, more than a half-century ago.

"Going forward it just looks like those numbers are going to increase and that's going to help us, not only with short-term drought but hopefully, with the long-term drought as well,"  said Andrew Schwartz, director of the UC Berkeley Snow Lab near Donner Summit.

The Department of Water Resources remote sensor network, reporting from 100 locations, is made of large, high-tech electronic scales which report 24/7. 

As of March 1, the network shows the Sierra snowpack in northern California is 150% of normal for this date, 191% in the central zone, and a whopping 224% in the southern zone. 

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That 40 feet of snow already up there, will melt into a most 4 feet of water. More is coming.  Early warm weather or warm rain could cause floods.

But so far, temperatures there have been very low keeping it mostly frozen. 

"Up here at the Snow Lab, we've seen temperatures, on average, during the day in the low to mid-twenties recently," said Schwartz.

On New Year's Day, the state's six largest mega reservoirs were 36% full.  Two wet months later there are 61% full; an enormous positive gain, but not the 86% it was previously.

"It's unlikely that we're going to completely end the drought with a single good season. We're going to need two of three of these consecutive years with above-average conditions," said Schwartz.

Recharging the underground aquifers-the majority of our supply-will take at least that long.