Avalanche Forecast
Regions: Glacier.
The strong spring sunshine and rapidly warming temperatures will actively trigger avalanches in the upcoming days. Start your day early, and scale back your exposure as the temperatures rise.
Remote and step down triggering of large avalanches is still a concern, with a robust crust/facet combo lurking ~1m below the surface.
Confidence
Moderate
Avalanche Summary
A field team in the Bonney area Wednesday observed several loose snow avalanches up to size 2.5, from the steep solar slopes of Ross Peak and Mt. Green.
Early this week, wind spikes triggered numerous avalanches up to sz 3, believed to be running in the new storm snow or on the reloaded Feb 3 bed surface.
Last Thursday, we observed naturally-triggered size 3 slab avalanches from Catamount Mtn SE face and Mt. Leda NE face. These were both deep, likely failing on the Feb 3rd crust.
Snowpack Summary
30-40cm of recent storm snow has been blown into a slab by strong Southwest winds in exposed areas. This new snow rests on a variety old surfaces, most importantly a thin suncrust on South & West aspects.
80-140cm of settled snow sits atop a sugary facet layer. These facets are not bonding well to the widespread, very firm crust from Feb 3rd. This crust is a significant persistent weak layer and will be a significant layer of concern for the foreseeable future.
Weather Summary
A ridge builds over BC, resulting in clearing skies, slackening winds, and rising freezing levels (FZL).
Tonight: Clear periods. Alpine low -9°C. Freezing level (FZL) 500m. Light W ridgetop winds.
Thurs: Sun/cloud. Alpine high -3°C, FZL 1500m. Light W winds.
Fri: Sun/cloud, Low -2°C, High 4°C. Temperature inversion. Light N winds. FZL 2500m
Sat: Sun/cloud. Low 3°C, High 4°C. FZL 3200m. Light ridge winds.
Terrain and Travel Advice
- Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
- Avoid exposure to steep sun exposed slopes.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
- If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Loose Wet
With sunshine and rising freezing levels in the forecast, avalanche activity is expected to increase on solar aspects. Minimize your exposure to Southerly slopes, especially during the warmest part of the day.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2.5
Persistent Slabs
This crust-facet combo (Feb 3rd) was created by a rain event followed by an extended cold, clear period without snow earlier this month. 80-140cm now sits on the persistent weak layer. Human-triggered avalanches on this layer remain possible, and resulting avalanches could be very large in size.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 2 - 4
Storm Slabs
Storm snow was accompanied by gusty SW winds. This built reactive soft slabs in lee areas. If triggered, these slabs may provide enough mass to trigger the deeper Persistent Weak Layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1.5 - 2.5