Intense snowfall and high avalanche hazard prevented the forecast team from conducting a site investigation. The following report is directly from party Involved.
Not clear if we remotely triggered this avalanche or if it released naturally from intense wind loading, but it struck us.
Left the trailhead at around noon intending to ski 30 degree trees in the Mammoth Rock area. We did our beacon checks thankfully and as we headed up the fire road and then broke off into the trees we saw two other skiers and a snowboarder. The winds had picked up and it had been snowing wet heavy snow but a skin track was still available most of the time. During the times there wasn’t a skin track available a pit was not needed to ascertain that there was almost a foot of heavy snow covered. We discussed the snowpack without digging a pit. You could clearly see it was upside down with I would say about a foot of heavy on about five inches of lighter snow. We continued skinning up until about 9000 when my spidey senses started firing. I was not seeing ahead of me anymore and definitely not above me at all. We were on a NE aspect on the leeward side of the ridge and the winds had increased. I couldn’t see much above me and the trees below and to the side of me did not show signs of avalanches but I was not comfortable. We ripped skins and prepared to ski down. I had not made a turn yet when a large avalanche from above knocked me over suddenly headfirst into the trees. I swam and felt like it wouldn’t be a significant burial but while fighting felt another heavy wave of snow push me further through the trees headfirst. When I was stopping I immediately started moving my face and my body as best as I could hoping to form an escape or face pocket. Except for my left arm, I was completely buried headfirst down the mountain. I had no idea where my partner was and started to use the left arm to dig out what seemed like a foot of snow above my head. It was becoming impossible because the snow had no where to go but I knew that was the only way I was going to survive. I worked to control my breathing so I wasn’t breathing in panic and wasting resources. Relief came when I could hear a voice above me and it took a minute to figure out where my head was but I was able to be recovered. My partner was also hit by the avalanche and carried a distance. He pulled his avy bag, and felt that it helped, and he was able to hold onto a tree. He lost his skis in this process. When the avalanche stopped, he pulled out his beacon and miraculously was able to uncover my airway within about five minutes. When he turned his beacon to search it read 33, he followed it downhill and was prepared to start probing when he saw my hand. I’ve been skiing in the backcountry for approximately 12 years and this was the first burial I’ve been involved in. I feel like this wouldn’t have happened if I turned around when I started feeling uncomfortable and I also wouldn’t be alive if my partner hadn’t been able to escape and quickly rescue me. I did lose both my gloves and my poles, and my partner never found one of his skis.
With close to 20” of snow falling overnight, (focused on the Mammoth area), and potentially a lot more snow on tap for today, be aware of new soft storm slab throughout the zone. Consider ALL ASPECTS at ALL ELEVATIONS for this problem as snowfall is expected to be rapid and intense. Travel in avalanche terrain is not recommended as this rapid snowfall will be sensitive and reactive to human trigger, especially in steeper 35+ degree terrain. Shooting cracks, audible whumpfing, and fresh fat looking slopes are signs of building storm slab. Overnight snowfall was less, but not insignificant in other parts of the forecast zone ranging from 6-9” in sheltered mid-elevation weather plots from Virginia Lakes down to Big Pine.
The intense snowfall, extreme winds, and rapid loading will test the weak old snow that resides at the base of the snowpack throughout the forecast zone. This moisture laden storm with heavy water content will add a lot of weight to underlying weak snow and avalanches could “step down” into old weak snow layers creating large and destructive slides. Areas of most concern are from around 9200ft to 10000ft in sheltered Northerly-Easterly terrain within trees. Weak old snow does exist widely and the condition should be considered on most aspects W-NW-N-NE-E-SE. Although we have found strengthening conditions at the interface between the old autumnal snow and last weeks big storm, this new additional load has the possibility of providing the trigger in exceptionally weak spots such as steep boulder strewn terrain with lots of cavities or convex roll overs.