Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1.5–3
This layer has been most reactive around treeline, particularly in areas that have not seen significant skier traffic.
Strong SW winds and rising temperatures will elevate danger levels in the Alpine, and potentially Treeline as well if wind values exceed the forecast.
This layer has been most reactive around treeline, particularly in areas that have not seen significant skier traffic.
Low density storm snow, moderate/strong ridge-top winds, and rising freezing levels will form soft slabs on variable wind-affected surfaces. Sensitivity to triggering will increase as the day progresses.
Recently, a large cornice-triggered natural avalanche stepped down to this basal layer near Grizzly Peak. Watch for steep, thin rocky areas where this layer could be activated.
No new avalanche activity observed in the hwy corridor Wed.
Several human-triggered sz 1-1.5 avalanches were reported over the weekend on Avalanche Crest, Hermit Slide path, and Swiss Couloir.
A natural cornice failure triggered a size 3 deep persistent slab on the SE slope of Grizzly Peak on Saturday.
25-30cm of low-density storm snow sits atop old wind-affected surfaces in the alpine and treeline.
The early Jan surface hoar is buried 50-80cm and is most prevalent at treeline. The November 17th facet weakness can still be found near the base of the snowpack in many areas.
Strong SW winds and warming on Thurs/Fri will elevate the danger levels in the short term.
Thurs: mix of sun and cloud, Alp high -6*C, 1100m FZL, mod/strong SW winds
Fri: mainly cloudy, scattered flurries, 5cm, Alp high -5*C, 1400m FZL, moderate/strong gusty SW winds