Avalanche Forecast
Issued: Mar 8th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Cornices.
astclair,
Avalanche Canada
Lingering wind slabs are the primary concern. Watch for denser, deeper drifts near ridge-crests and rollovers and give cornices a wide berth from above and below.
Summary
Confidence
Weather Forecast
Dry conditions and diurnal cycles for the next few days
Monday night: Mostly clear, light to moderate southeast wind, freezing level dropping to valley bottom.
Tuesday: Mix of sun and cloud, isolated convective flurries with trace accumulations, light south wind, freezing level rising to 1300 m and dropping to valley bottom.
Wednesday: Mix of sun and cloud, light southwest wind, freezing level rising to 1100 m and dropping to valley bottom.
Thursday: Mainly sunny, light variable wind, freezing level rising to 1100 m and dropping to valley bottom.
Avalanche Summary
On Sunday, small pockets of wind slab were reported releasing naturally and with ski cuts, primarily on northerly aspects near and above 1900 m. Small loose dry sluffs were also observed in steep terrain.
Explosive mitigation on Saturday produced numerous large cornice and storm slab avalanches, with 50-100 cm crown depths. Explosives also released a very large (size 3) wind slab avalanche on a northeast aspect above 2000 m.
Reports indicate that a natural avalanche cycle occurred during the storm on Friday, with small to large (size 1-2.5) avalanches releasing in the storm snow across aspects and elevations. See this MIN and this MIN for examples near Rainbow Mountain.
Snowpack Summary
50-100 cm of snow accumulated over the weekend that has been settling rapidly. The recent snowfall was accompanied by strong south winds, forming wind slabs on leeward slopes that remain possible to trigger. Massive cornices exist on ridgelines, which can act as triggers on slopes below.
The mid and lower snowpack is well settled and strong in most areas. A weak layer of facets buried in mid-February may still be found but has been gaining strength.
Terrain and Travel
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Cornice failure may trigger large avalanches.
Problems
Wind Slabs
Strong south winds have had ample snow to drift into reactive wind slabs on lee features at upper elevations. Pay attention to the pattern of wind-drifting in the terrain where you are traveling and watch for cracking or changes in snow stiffness. Triggering large wind slabs on specific features remains possible.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices have seen substantial growth since the last storm, and they may release naturally with the impact of solar radiation. Cornice falls can act as triggers on slopes below.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 9th, 2021 4:00PM
