Earlier in day myself and partner skinned up and skied, twice, over part of slope that later slid and that is the subject of this report. Our high point was at tree groups at around 6100 ft which was just below the later crown. We saw no indications of instability today (until after the slide) or any signs of instability the two prior days at same area. A separate party of two was skinning up our track as we had descended our second run. We encountered them going up as we had already descended about 500 ft. Our runs were about 1000 ft vert. We put on skins to ascend for a third lap. About halfway up the skin track, we see an oncoming avalanche cloud and debris wave coming over the crest directly above us headed our way. Nightmare. I grabbed a nearby tree as tight as possible and lifted my legs/skis to allow debris to flow past. This strategy worked. One ski ended up somewhat buried. My partner was a few hundred feet away and was outside of the debris flow. We were ok. Knowing a party of two was above us we ascended 400 ft to check them. Upon seeing the size of the crown and debris, we put our beacons into search. Fortunately we found them both above the snow ok.
From debriefing with the other group, when the slide happened they were skinning up our prior uptrack and near our prior high point at the tree island. They said they did not feel any settlement but heard a whoomph and saw the slope come down. One of them grabbed a tree and snow slid over and around him, breaking one of his poles. The other fell in the sliding snow and was carried and buried, but their partner quickly unburied them.