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Avalanche Forecast

Archived

Jan 13th, 2025–Jan 14th, 2025

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Glacier.

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.

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

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.