Avalanche Forecast

Archived

Mar 9th, 2023–Mar 10th, 2023

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Jasper, Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Maligne, Marmot, Miette Lake, Pyramid.

Solar radiation has an effect on the snowpack mid day through mid afternoon on steep sun affected slopes. Even though proper spring is yet to arrive, significant diurnal swings of up to 20 °C between the morning and afternoon are stressing the already weak snowpack.Ice climbers should be especially careful in sun exposed low elevation gullies as even a small slide could have serious consequences.

Thin to thick areas are most suspect spots to trigger the deeper instabilities.

Confidence

Moderate

Avalanche Summary

Avalanche control on Hwy 93N with the use of large explosives resulted in few wind slab and numerous loose dry avalanches up to size 2 on Wednesday.

Natural activity has tapered off but the snowpack has proven sensitive to small inputs of new snow, loading, temperature change, and potentially solar effect. Careful evaluation of these inputs is essential.

Don't forget to post avalanche observations to the MIN.

Snowpack Summary

In sheltered areas the top 20 to 40cm is comprised of low density facetted crystals. There is extensive wind effect at tree line and above from previous SW winds. Sun crust is forming on steep solar slopes at tree line and below.

This is sitting on top of a generally weak mid and lower snowpack. Facets and depth hoar linger at the base of the snowpack with the height of snow varying from 60 to 160cm.

Weather Summary

The surface ridge of high pressure will remain in place until Friday. Clear skies, variable light wind, and temperatures slightly below seasonal are expected. Freezing level forecast to remain at or near valley bottom. An upper low may bring some flurries Friday and Saturday.

Detailed weather forecasts from Avalanche Canada: https://avalanche.ca/weather/forecast

Terrain and Travel Advice

If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.