The Snow Pack
Despite a fluctuating snow level that at times soared to nearly 9,000 feet, Sierra ski resorts now can boast they have some of the best snow pack conditions in the nation.
--Palisades Tahoe has more than 6 feet of snow on its upper mountain.
--Sugar Bowl's base is nearly 8 feet deep.
--Mammoth Mountain's pack doubled from 6 feet to 12 feet between Christmas and New Years. On New Year's Day, Mammoth picked up 55 inches in just 24 hours, an impressive dose but still well shy of the Sierra, 24-hour snowfall record of 67 inches set in January 1982 at Echo Summit.
--Kirkwood's snow pack is now approaching 14 feet deep; the resort has received nearly 24 feet of snow so far this season.

If you're wondering why Tahoe skiers now routinely expect plenty of snow early in the season, out of the top ten wettest Decembers in San Francisco since 1849, three of them have occurred since 2001. And this does not include 2004 which was very wet and snowy in the mountains but failed to make the top-ten ranking in San Francisco. In short, four of our last five winters have started early and we here have become used to it in spite of history to the contrary.

Avalanche Danger
With the fresh snow come cautions. According to the Sierra Avalanche Center, the risk of avalanches near and above the tree line is "MODERATE" today, Jan. 3, with areas of "CONSIDERABLE" risk on recently wind-loaded NW-NE-SE mountainsides steeper than 34 degrees. Below the tree line, avalanche danger is "LOW" with isolated pockets of "MODERATE" in open areas steeper than 35 degrees.

Winds and recent snow accumulations have heightened the risk of wind slabs in backcountry areas between Yuba and Sonora passes. According to the Center: "Yesterday (Jan. 2) there were widespread reports of instability in the form of shooting cracks in recently wind-loaded areas. There were also easy shears from layer-bonding tests in the top 20cm of the snow pack. Light winds in the past 24 hours have left lots of snow available for wind transport, despite the end of significant precipitation. Boot penetration observed yesterday ranged from 1 - 3 feet. This is the snow that is still available for transport to lee areas."

Wind slabs will continue to be sensitive in areas underneath cornices where the greatest snow pack instability has been observed. Slide-causing shears may become more active if they are buried below the level of ski, snowboard, and snowmobile penetration. Human triggering of slab avalanches ranging from 1 - 4 feet deep is probable today (Jan. 3) in lee (down wind) areas beneath cornices. Natural avalanches in these same areas are also in the realm of possibility.

Resorts use explosives to reduce avalanche hazards on their slopes. However, even after precautions, a large slide at Palisades Tahoe on Dec. 29, 2005, nearly caught four skiers. This provides living proof that dangerous avalanches can occur anywhere. At Squaw the slide path, which was 250 feet long by 200 feet wide, was caused by an abrupt temperature change. Between 11 a.m. and 2 p.m. on Dec.29 the temperature plummeted 20 degrees!

Mark McLaughlin is a weather historian who lives on the North Shore of Lake Tahoe.