usual worm flows winter route from marble mountain. having crossed chocolate falls, and following the trail markers, we had ascended the left (climbers left) worm flow per the most direct route.
Feb. 19, 2017, 1 p.m. PST
Weather: heavy snowfall, not too wet.
Snowpack: layers felt well consolidated other than the next snow that was occurring.
Area Description: South face of Helens.
Avalanches: On worm flows route following the left worm ("bad worm") we triggered a moderate wet slow moving avalanche at ~4600-4800 ft (I think, I forgot to check my altimeter) while climbing on skis/skins. Occurred as we were traversing from the windward side of the rocks (leward side had a cornice and visibility was very poor so we had moved to windward side for safety). Avalanche occurred as we neared the top of the rock ridge/worm flow and were traversing climbers left in to the basin. We could see a 4-6 inch crown where the avalanche started 10 feet above and climbers left of us originating from the leward side of the ridge left of us, but it extended up out of site (white out) and rightward (northeast) in to the flat "headwall" that connects that left ridge and the worm flow ridge just before you pop out on to the higher plateau, so it may have been larger higher up and out of site. I say this because there was enough snow to bury me to my waist, and my partner to his armpits. Of course this was in the heavy snowfall that was occurring on sunday. we knew there was some risk, were carrying transceivers and gear, but thought we were far enough on to the windward slope that slides were unlikely. However, of note we were seeing 6 inch long cracks forming under the skies in the new layer even on windward slopes. We had not dug a pit on any of the slopes.
Did you see any avalanches? Yes
Did you trigger any avalanches? Yes
Was anyone caught in an Avalanche? Yes