Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
A series of storms will affect the region starting Saturday evening. Although recent models have backed off the forecast snowfall amounts, the avalanche hazard will rise into Sunday and may increase further into the start of the week.
If more snow arrives than has been forecast expect the hazard to increase rapidly.
Confidence
Moderate
Avalanche Summary
Another close call to the north of Golden occurred Friday. Skiers triggered a sz 2 slab at 2150m 30cm deep and 30m wide on a west aspect that buried one skier.
A fatal avalanche occurred south of Golden on Monday. A small windslab on a north aspect at 2300 m carried one person a long way (1000 m) down a steep, confined gully with many terrain obstacles.
We are anticipating an avalanche cycle starting Saturday night with the incoming storms.
Snowpack Summary
The new snow will bury a significant drought layer. Surface faceting is the dominant condition with extensive wind effect found in the alpine. Sun crusts have formed on steep solar slopes and surface hoar has developed in sheltered areas.
The mid-pack is generally weak facets, while depth hoar over a crust forms an even weaker base. The snowpack is the weakest in eastern areas where snow depths are low. In these areas, the basal weaknesses should be carefully considered.
Weather Summary
A warm front will pass over the region late Saturday afternoon. We expect 5-15cm overnight with continued strong SW winds in the alpine. Freezing levels will drop from near 2000m to valley bottom.
Sunday morning a cold front will pass. Up to another 5cm of snow is expected by mid day as freezing levels return to around 2000m.
The next system arrives Sunday night with another 5-10cm of snowfall forecast.
Terrain and Travel Advice
- Be careful as you transition into wind-affected terrain.
- Loose avalanches may start small, but they can grow and push you into dangerous terrain.
- Make conservative terrain choices and avoid overhead hazard.
Avalanche Problems
Wind Slabs
A combination of older stubborn wind slabs and newly forming slabs overlie a heavily faceted snowpack. As new snow accumulates and strong winds continue, we expect this issue to become more reactive.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2.5
Loose Dry
Wind speeds are expected to stay in the strong range into Sunday. We anticipate this will trigger the heavily faceted upper snowpack, leading to loose dry avalanche activity in steep terrain. Expect loose wet activity at low elevations.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2
Deep Persistent Slabs
As a natural cycle begins with wind slabs and loose dry avalanches occurring more frequently, this moving snow may step down into the weak midpack and basal layers resulting in larger avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3