TRUCKEE (CBS SF) — Mother Nature continued her wintry onslaught on the Sierra Wednesday, dumping a foot and half of new snow at the Homewood ski resort over a 24-hour period and triggering a backcountry avalanche watch for the entire Lake Tahoe basin.

The National Weather Service said Kirkwood had gotten 16 inches of snow, Sugar Bowl 15 inches, Sierra-At-Tahoe 13 inches and Squaw 12 inches or more over the last 24 hours.

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The storm was the second of three that will roar through the area this week and the heavy snowfall was contributing to what were already dangerous conditions.

It was just two weeks ago that a pair of avalanches walloped two ski resorts in as many days, fortunately no one was killed.

The Mono County Sheriff’s department said three people were partially buried in an avalanche at Southern California’s Mammoth Mountain ski resort while five people were swept up by an avalanche at Squaw Valley.

Three people were uninjured, one was treated for minor injuries but the fifth was hospitalized with a serious lower body injury.

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In another freak accident, a San Francisco woman and her young son were killed when snow fell from the roof of a ski condo, burying them as they returned home from the slopes.

The Alpine County Sheriff’s Department said 50-year-old Olga Perkovic and her son were about 30 feet from their front door when a chunk of snow about the size of a trailer fell on them.

Their bodies were found under 3 feet of snow.

Wednesday’s stormy weather triggered a backcountry avalanche watch with the Sierra Avalanche Center issuing a warning that there was a considerable danger for a snow slide.

The National Weather Service had issued a winter storm warning for the Lake Tahoe region until 11 p.m. Wednesday above 4,000 feet. Blowing snow was making travel hazardous on I-80 and Highway 50 with chains required in the higher passes.

Above 7,000 feet, forecasters said, an additional accumulation of 6 to 9 inches was expected with as much as a foot in some localized areas.

For Thursday afternoon through early Saturday, the weather service, additional snow accumulations of 12 to 20 inches were predicted at lake level with 2 to 3 feet above 7,000 feet.

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Another winter storm warning was scheduled to go into effect from 5 p.m. Thursday to 5 a.m. Saturday.