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Avalanche Forecast

Archived

Jan 25th, 2023–Jan 26th, 2023

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

Regions

Pine Pass.

There is uncertainty with the reactivity of deeply buried weak layers with recent warming and new snow. It is best to manage this uncertainty by sticking to lower angle terrain away from any overhead hazard.

Read more in our latest forecaster blog.

Confidence

Moderate

Avalanche Summary

Recent reports indicate explosives controlled wind slab avalanches to size 2.5 running on east and southeast aspects in the alpine.

Reactive wind slabs will continue to form, but concern for step-down and large natural and human-triggered deep persistent slab avalanches is at the forefront of our minds. Check out this video on incremental loading to learn more.

Please continue to send in your observations through the MIN.

Snowpack Summary

Recent new snow accompanied by strong northwest winds continues to build wind slabs in lee terrain.

Snowpack depths are shallower than normal, and several buried weak layers have been a concern over the past few weeks. Surface hoar or crust layers in the mid-snowpack may exist in this region, but field observations suggest these mid-snowpack weaknesses are less prominent here than in areas further south.

The most concerning layer in this area is at the base of the snowpack. Large, weak facets buried in November are widespread. This layer is most likely to be problematic in steep, rocky alpine terrain, where shallower wind slab avalanches can scrub down to these basal facets.

Weather Summary

Wednesday Night

Cloudy with clear breaks and isolated flurries. Ridge wind northwest 50-80 km/h. Alpine temperature -3 C. Freezing level 1400 m.

Thursday

Cloudy with sunny breaks. Ridge wind northwest 40-80 km/h. Alpine temperature -4 C. Freezing level 1500 m.

Friday

Mainly cloudy with flurries. Ridge wind northwest 15-40 km/h. Alpine temperature -8 C. Freezing level valley bottom.

Saturday

Mainly sunny. Ridge wind northeast 45 km/h. Alpine temperature -15 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • Uncertainty is best managed through conservative terrain choices at this time.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.