Avalanche Forecast
Issued: Jan 13th, 2025 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs.
Parks Canada,
Avalanche Canada
Hey y'all! There's a persistent weakness (surface hoar) buried 30-50cm below the snow surface. It is primed to fail under the weight of a person if the slab has enough stiffness to propagate.
Consider cooling your jets, everyone, and maybe leave the big, bold lines alone until you're sure this problem has been flushed away.
Summary
Confidence
Moderate
Avalanche Summary
Skier triggered sz 3 in Lone Pine today, ran ~1000m and accumulated significant mass. Heads up, folks!
The natural cycle has slowed, human triggering remains possible to likely where the new snow overlays surface hoar and has stiffened into a surface slab. There have been several reports of rider triggered avalanches up to size 1 in terrain adjacent to Glacier National Park.
Snowpack Summary
We've received ~50cm of new snow since Jan 7th. This new snow buries a weak interface, which consists of widespread surface hoar on all aspects into the high alpine, and a thin suncrust on steep S to W aspects. Moderate southerly winds have redistributed this new snow in wind exposed terrain. Where the new snow is stiff enough, it has been reactive in tests, indicating high propagation potential.
Overall the mid and lower snowpack is strong and well settled.
Weather Summary
Slight temp inversion the next 2 days, then a minor pulse of snow on Thurs.
Tonight Mainly cloudy. Alpine low -8°C. Wind W-15km/hr. Freezing level (FZL) at valley bottom.
Tues Mainly cloudy. Alpine high -2 °C. Wind W-25km/hr. FZL 1400m.
Wed Cloudy with sunny periods. Alpine high -1°C. Wind SW 30-40km/hr. FZL 1700m.
Thurs Flurries. 10cm. Alp high -6°C. Gusty winds, W 25 to 75km/h. FZL 900m.
Terrain and Travel Advice
- Be especially cautious as you transition into wind-affected terrain.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks, or recent avalanches.
- Avoid areas where the snow feels stiff and/or slabby.
Problems
Persistent Slabs
Up to 50cm of new snow this week is settling into a slab, even where sheltered from the wind. This slab is reactive in tests at Treeline and above, and shows a potential for significant propagation. It was likely the culprit in the skier-triggered, size 3 avalanche on Lone Pine today.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 14th, 2025 4:00PM
