Avalanche Forecast
Regions: Pine Pass.
Dangerous avalanche conditions exist in this region. Wind and warming will continue to test a fragile snowpack. Read more in our latest forecaster blog.
Confidence
Low
Avalanche Summary
On Sunday, numerous natural wind slabs (size 2-3) were observed. These slabs initiated as wind slabs but scrubbed down to basal facets, gaining mass and running far.
This week, 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. Westerly winds redistributing surface snow in conjunction with warming temperatures continue to add load to a shallow, weak snowpack. It is uncertain when the "tipping point" for large destructive avalanches will be reached, and this uncertainty demands conservative and low-consequence terrain selection. Check out this video on incremental loading to learn more.
Please continue to send in your observations through the MIN.
Snowpack Summary
A light amount of new snow accompanied by strong northwest winds continues to affect wind-exposed terrain and redistributed the surface snow into fresh wind slabs in lee areas. Below the new snow, a sun crust may be found on steep solar aspects. Below 1200 m, a rain crust exists down 20- 40 cm.
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
Tuesday night
Cloudy with isolated flurries, less than 5 cm accumulation. Alpine temperatures rise to -2 C. Ridge wind northwest 45-70 km/h. Freezing level rises to 1300 m.
Wednesday
Cloudy with isolated flurries. Alpine temperatures rise to -1 C. Ridge wind northwest 40-70 km/h. Freezing level rises to 1600 m.
Thursday
A mix of sun and cloud. Alpine temperatures remain elevated around -2 C. ridge wind northwest 45-60 km/h. Freezing level 1500 m.
Friday
A mix of sun and cloud. Alpine temperatures drop to -6 C. Ridge wind northwest 25-40 km/h. Freezing level 500 m.
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.
Avalanche Problems
Wind Slabs
Strong to extreme northwesterly winds will continue to transport surface snow and form fresh, reactive wind slabs in the alpine and treeline.
With a shallow and weak snowpack, be aware that wind slabs can easily scrub down to the basal weakness creating large and consequential avalanches.
Aspects: North, North East, East, South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood: Likely - Very Likely
Expected Size: 1.5 - 2.5
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. This layer has most recently been problematic in upper treeline/lower alpine elevations.
Avoid thin and rocky start zones where weak layers sit closer to the surface, riders are most likely to trigger an avalanche on this layer in steep, shallow previously undisturbed terrain or by first triggering a layer further up in the snowpack.
Remote triggering is a concern for this layer, avoid travelling below steep slopes.
The likelihood of avalanches will increase as wind and warming add load to a fragile snowpack.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 2 - 3.5