By Paula Peterson
SOUTH LAKE TAHOE, Calif. – Snow avalanches kill more people in National Forests than any other natural hazard. Each winter, 25 to 30 people die in avalanches in the United States, and nearly all of these deaths involve recreation on National Forest land.
The high number of avalanche deaths in a seven-day period was just recorded with 14 people dying in an avalanche. This was the deadliest people since the U.S. Forest Service’s (USFS) National Avalanche Center started tracking deaths, according to Karl Birkeland, the center’s director.
While there have been no deaths from avalanches in the Lake Tahoe area this season, activity recorded with the Sierra Avalanche Center (SAC) show February has been a very active period. There have been 33 observations of avalanches between Donner Summit and Blue Lakes since February 12 (see list of snowpack and avalanche observations here). The forecast for the next two days in the region is for moderate avalanche danger. Gusty winds will keep a wind slab avalanche problem possible in near and above treeline areas and wet loose avalanches will become possible with daytime warming. Recent rain crusts could make for challenging travel conditions along the Sierra Crest with potential fall hazards.
On Friday, February 12, a South Lake Tahoe man was skiing in the backcountry with a friend in the Upper Blue Lakes area when he found himself in the middle of an avalanche. He was carried 100 feet over a cliff according to Alpine County Undersheriff Tom Minder. His department’s Search and Rescue team responded along with Lake Valley Fire and they were able to get to the man and Careflight provided transport to Renown Medical Center in Reno.
“This guy got lucky,” said Minder.
There have been other avalanches that have involved people in the Sierra during the 2020/21 winter.
There is no “normal” when describing annual avalanche activity, according to Andy Anderson, a forecaster with SAC.
“Each winter is different, each avalanche is different,” said Anderson.
The wind, rain, snow, temperatures all play a part in avalanches, so every winter is different in the terms of avalanche probability and activity.
Anderson said wind slab and storm slab avalanches are more common in the Sierra. The wind slab is when a cohesive slab of snow is formed when wind deposits snow onto leeward terrain. They are often smooth and rounded, and sometimes hollow. The storm slab is release of a soft cohesive layer (a slab) of new snow that breaks within the storm snow or on the old snow surface. Storm slabs are most dangerous on slopes with terrain traps, such as timber, gullies, over cliffs, or terrain features that make it difficult for a rider to escape off the side. Temperatures change during a storm, as does the rate of snowfall, sometimes creating a heavier layer of snow on top of a lighter layer.
Wind slabs are on more open areas, storm flabs in sheltered areas, explained Anderson.
“Know the slabs where you are going and where to avoid,” said Anderson.
If heading out into the backcountry it is very important to know the snow conditions, and SAC is a valuable resource for all winter recreationists, including the forecast from scattered weather stations. While this website is important, having all tools available is best.
“Give yourself the tools to make the best decisions,” said Anderson. “Take a class, have the right equipment, check forecast, and visit the SAC site.”
Together all of these gives one the skills, knowledge, equipment to make the best decision in the snow.
Lake Tahoe Community College is one of several local providers for avalanche nd rescue education (see list here).
Avalanche Centers produce and distribute safety messaging designed to inform the public on current and upcoming avalanche conditions. Sierra Avalanche Center (SAC) in Truckee is one of 15 centers associated with USFS in the country. There are also six non-profit avalanche centers and one operated by a state.