Observation: Public
Observation Details
Name:
Enji CooperObservation Date:
March 18, 2023Submitted:
March 19, 2023Zone or Region:
West NorthActivity:
XC Skiing/SnowshoeingLocation:
Ruby Mt via Happy Creek drainageTriggered Avalanches
Did you trigger any avalanches?
YesWas it intentional?
NoAvalanche Type:
Dry Loose (Sluff)Size:
Size 1: Relatively harmless to peopleElevation:
ATL (5.5k'+)Aspect:
NEComments:
Was triggering lots of small/localized sluffing on descent when hopping through the snowpack in my snowshoes.Observed Avalanches
Did you observe any avalanches?
YesAvalanche Type:
OtherSize:
Size 2: Could bury, injure, or kill a personElevation:
Aspect:
EComments:
Observed D2-sized avalanches off E/SE facing cliff coming off north arm of Ruby at ~(48.70189, -121.04715). Slides seen around 11~12 and led into the Happy Creek drainage. Cliffs were well in excess of 50°, but the trigger was from near the top of the ridge.Signs of Unstable Snow
Did you see shooting cracks?
Yes, IsolatedDid you experience collapsing or whumpfing?
Yes, IsolatedObservations
Conditions yesterday were very early/mid-spring-like (late March~mid-April). Day started above freezing at the Ross Lake TH (~37° at 6:30am) and ended at 44° (6:00pm). The snowpack BTL was mostly zipper crust over a couple inches of facets, then became slightly more supportive above 3k' under the trees. Areas out in the open had drier powdery snow (small facets) and slightly deeper snowshoe penetration than under the trees (1"~2" vs 3"~5").
I was snowshoeing up the skin track without disrupting it successfully up to NTL, but it was late enough in the day around ATL (~5.75k') that I hopped off the skin track and started breaking my own trail. Trailbreaking provided interesting observations (soft wind slabs cracking) and I started noting some localized collapsing of ~3" when stepping and putting weight on my snowshoes. I did a bit of digging and found some larger sugary facets (no consolidation) above ~1.5' of deep consolidated fetch (felt like 4F+/1F pressure compaction). Did some HSTs along the way and observed mixed qualitative results, but the overall theme was that the stronger consolidated layer was not bonded at all to the facets and was very prone to sliding if hit at the right angle/depth (sudden planar break). My guess is that this was the layer that hit so many riders this past week around the Baker portion of the zone.
Trying to play it a bit safer due to uncertainty, I limited my time around terrain traps (convexities/cols) and limited my exposure by taking more aggressive uphill tracks cutting the switchbacks of the skin track set by skiers and boarders. I waited at the summit for at least 45 minutes to 1 hour watching riders drop into the col that led into the Happy Creek drainage so I could better assess the surface layer instabilities in the snowpack. There weren't any apparent instabilities triggered by the riders. Playing it safe still since I was concerned about sharks below the surface, I stuck to more shaded sections of the ridge and tried to give myself enough buffer around steeper convexities which lead into shallow drainages/cols. I didn't want to get carried downhill and buried -- especially since the riders were heading skier's left and I was heading skier's right, and the likelihood of potential rescue was lower the way I went down.
The snow continued to be dry up to 4.5k', but then got a lot wetter/sloppier (close to light smashed potatoes). Tree bombs were going off in the late afternoon when I took a break at 3.5k'.
Media
