Avalanche Forecast
Regions: Banff Yoho Kootenay.
The avalanche hazard will increase over the day as forecasted winds intensify, watch for fresh wind slab.
Uncertainty exists around the persistent layers in the snowpack, as some deep releases have occurred recently and lowered our confidence.
Weather Forecast
A mix of sun and cloud for the majority of Friday as 5-10cm of snow is forecasted for late Friday afternoon into Saturday morning. Winds are expected to be 30-75km/hr from the South West. Freezing levels will reach 1400m. Clearing trend for early next week.
Snowpack Summary
10-20cm of snow in the past 24hrs now buries a crust up to 1800m, higher on steep solar aspects. New wind slab growth in the alpine down into tree line. Several persistent layers exist in the mid to lower snowpack and have been responsible for several large avalanches. These layers will remain a concern for some time due to their uncertainty.
Avalanche Summary
A loose dry avalanche cycle occurred during the intense flurries on Thursday. Several cornice failures and small slab releases digging down and triggering deep releases up to size 3.5 over the last 4 days (Des Poilus, Vulture Pk, Lake Louise area, etc.). A nearly, full burial occurred on Wednesday in alpine terrain around Lake Agnes, no injuries.
Confidence
Avalanche Problems
Wind Slabs
Thursdays storm brought 10-20cm of new snow with moderate South West winds. Strong winds are forecasted on Friday and will likely form new wind slab in alpine and open tree line terrain.
- Be careful with wind loaded pockets, especially in steep confined alpine terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Persistent Slabs
Several deeper releases occurred over the past 4 days (see avalanche table). There is a lot of uncertainty as to which layers within the snowpack these slid on. We will be monitoring this in the coming days to see if it continues.
- Pay attention to overhead hazards like cornices which could trigger persistent slabs.
- Pockets of persistent slabs linger on alpine lee features.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3.5
Loose Dry
Anticipate loose dry activity in steep alpine terrain, especially in confined or exposed terrain features where even a small sluff can have severe consequences.
- Be careful of loose dry power sluffing in steep, confined or exposed terrain.
- If triggered dry loose point releases can form deeper deposits in terrain traps.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Likely
Expected Size: 1 - 1.5