Several local snow professionals reported a huge and destructive deep, persistent slab avalanche at one of Washington’s busiest backcountry areas, Source Lake in the Alpental Valley.
Sometime between late Sunday afternoon and early Monday morning, an enormous avalanche released from the upper basin of Chair Peak. The slide descended more than 2000’, crossed Source Lake, overran a small knob, and traveled 300’ into the small trees beyond. Debris from this event covers numerous common travel routes and a very popular lunch spot. While this avalanche is impressive, the vegetation in the area shows it can produce even larger slides.
Many of our forecast zones continue to struggle with this same deep, persistent slab avalanche problem. Over the last week, we have received near-daily observations of slides with 8-10’ crowns that are hundreds of feet wide and/or that destroyed mature timber.
This particularly tricky avalanche problem has not gone away and continues to shape our terrain selection. Any large avalanche path should be suspect. Make sure to check your local forecast for the latest information on this potentially dangerous snowpack structure. Thank you to everyone in the community for submitting observations that help us track avalanches issues like this.
Chair Peak, NE-E-SE, 5800’ Crown >10’, HS-N-D3.5-R4-O