Recent avalanche activity
Whumpfing sounds or cracks
Sat, Feb 13, 2021 - 4:30 PM
Avalanche Activity Caught, Buried, or Injured Person
Ski or Snowboard
Reporting on presumed natural slide conditions as well as a skier triggered slab on NE aspect of Tumalo that resulted in a partial burial of a party member who had already skied at the bottom of the slope.
Party of 7 consisting of 4 locals and 3 visitors. Extensive experience between the party members, avalanche education, extensive travel in multiple ranges, and each with average of 20 years backcountry experience although some more active and current than others.
Party left TH (Dutchmans) around 13:00 and was on top around 14:00. Small crown (~12") and debris below noted upon arrival in the area of the skier/sled boundary line mid-face. Visibility ok but not great, could see trees at the bottom of bowl but snow surface itself difficult to make out. Couldn't make out any ski tracks and thus presumed crown/debris to be naturally occurring.
After some discussion we decided to put in a ski cut with the hopes of skiing. Ski cut was put in roughly from the top of the rocks in the middle of the face, southerly to the bed surface of the previous slide. Nothing moved and the snow felt stable underneath. Proceeded to ski down and the rest of the party followed, all skiing just skiers left of the initially observed path. Collection point on a small ridge above a depression at the bottom of the bowl. Opted to ski another lap so headed back up. Debris noted along far skiers left margin of bowl as well while we were hiking up ridgeline to top, appeared to be small cornice failure induced.
Dropped in to second lap, skiers left of previous line, just skiers right of the rocks, around 15:15. 6 of the 7 skiers stayed right of the rocks. May or may not be relevant but 7th skier skied within the rocks but far right hand side, skier may have helped undercut and unsupport the slope above. Same/similar collection point. Opted for one more lap so went up again.
At this point we had made a fairly significant impact on the slope. The first three skiers opted to ski the terrain already tracked with the remaining 4 skiers intending to ski fresh snow slightly left of the one line that had been skied through the rocks. Three skiers below in the same/similar collection point. First skier (snowboarder) to start the new line triggered slab with roughly 20" crown. Rider stopped upon trigger at the top of the crown and was verbalizing what he could see but remaining skiers up top could not see the slide itself although we could see the people below. Rider articulated that it was significant but also didn't seem terribly concerned. At some point he began to yell to party below at which point remaining skiers did as well. Visibility was still poor, from above we could tell there was a cloud of snow but could not tell where it was. It did clear and it appeared as though we could see all party members below. Rider proceeded to bottom of hill. The next two skiers each cut off a small amount of the unsupported crown and skied the bed surface for the first half of the run. Final skier didn't get anything to move. Everyone collected at the bottom.
The snow ran all the way through the collected party at the bottom. One person, skis on and poles in hand, was unaffected and mobile. One person with one ski on but one ski off and poles in snow had enough snow come in on top of them that they had to excavate their ski a bit to become mobile. This persons removed ski and poles became buried. The third person had skis on but poles planted off to the side and was in the most direct path of the snow and was buried to the point of incapacitation and needed to be uncovered by the remaining two skiers. The partially buried person also lost a pole but was uncovered by the time the rider who triggered the slide was down. The missing ski was thankfully recovered but the three poles were not. Additionally, while searching for the ski and poles, a significant whumph was heard by most in the party. Due to impending darkness we didn't spend long looking for the poles.
There was another party of three who did one run in the bowl far skiers left side more or less concurrently with this incident, to our knowledge unaware of any of this happening. We did not see any other evidence of skier traffic in the bowl although it was snowing heavily and wind transport was significant so easily could have filled in any prior lines.
Plenty of take aways or potential take aways depending on your perspective or risk tolerance. After debriefing as a party, the primary thing that we should/would have done differently was the point of collection. We thought that it was far enough in the flats and somewhat protected by the depression but this did not prove to be true. The remaining skiers on top would have also ideally had a better vantage of the line being skied although this is difficult in the area being discussed as it rolls over quickly. We also discussed not being in a state of transition while others are skiing above. Even the skier who was not transitioning, however, and had eyes on upslope, could not tell that snow was moving until it was almost upon them. The snow risk itself was discussed and conscious decisions were made. It was not necessarily surprising that the slab went although it did go bigger and longer than any of us expected. The risks seemed calculated and manageable although we were still caught surprised by the extent of the slide and very lucky that we got off as lightly as we did. We were pushing darkness too closely and there was undoubtedly some slope comfort based on familiarity. Even if we thought we were managing our own risks for ourselves, there was also another party skiing elsewhere that just as easily could have kicked something off in the area that we had not evaluated for ourselves but which we had to cross beneath to hike back out.