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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.
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

South Rockies, St. Mary, Bull, Elkford East, Elkford West.

Diligently maintain a conservative mindset. You may not see signs of instability on the surface however the deep persistent weak layer remains a major concern at the bottom of the snowpack.

Avoid shallow rocky terrain where the snowpack transitions from thick to thin and triggering the deep persistent layer is more likely.

Confidence

Moderate

Avalanche Summary

No recent avalanches have been reported in this region.

On Tuesday, a deep persistent slab avalanche was triggered by a cornice or solar input in extreme, rocky terrain in the Elkford area. See the MIN for a photo.

Snowpack Summary

Flurries accumulate over 40-50 cm of wind-affected snow in the alpine and open treeline. On solar slopes, they overlie a thin sun crust.

In the Purcells several weak layers from Jan and Feb can be found down 50 to 120 cm however they are showing signs of strengthening. The mid-snowpack is generally well settled.

The lower snowpack is made up of a widespread layer of large, weak basal facets and depth hoar in some areas. this weakness has been responsible for a number of recent very large, destructive avalanches and will continue to be a concern.

Weather Summary

Thursday Night

Increasing cloud through the evening. Southeast winds 15-25 km/h. Treeline temperature low of -12.

Friday

Cloudy with scattered flurries, 2-6 cm accumulation. Southeast ridgetop winds 25-40 km/h. Treeline temperature high of -9.

Overnight flurries continue 1-3 cm accumulation. Winds switch to the west 20 km/h.

Saturday

Cloudy with sunny periods and isolated flurries, trace accumulation. Southwest ridgetop winds 20 km/h. Treeline temperature high of -5.

Sunday

Cloudy with sunny periods and isolated flurries, trace accumulation. Southwest ridgetop winds 20 km/h. Treeline temperature high of -3. Freezing levels rise to 1400 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid areas with a thin or variable snowpack.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
  • Avalanche hazard may have improved, but be mindful that deep instabilities are still present.

Problems

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.