Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
Things have changed, and temperatures have warmed up!
With warming comes the potential for increased sensitivity to triggering.
Watch for newly formed wind slabs and the potential for initiating the deep persistent problem in thin to thick areas.
Confidence
Moderate
Avalanche Summary
Lake Louise reported a couple of size 2 explosive results on wind slab stepping down to the ground on Jan 20.
On Jan 19 Sunshine reported explosive results on the basal facets up to size 3 specifically on an alpine southerly facing feature called Jaws (out of bounds)
Additionally, wind slabs have been reactive to skier traffic and explosives up to size 2.
Within the last 24-72h there have also been several avalanches out of extreme terrain to size 1.5, loose dry and wind slabs.
Snowpack Summary
10-20 cm of recent snow has formed windslab and widespread wind effect in the alpine and exposed areas at treeline. 30-50 cm overlies the Dec. 31 surface hoar/sun crust. Below this, in the mid-pack, two crusts (Dec. 22 and Dec. 5) exist as high as 2350m and have been providing the primary support for skiing. The base of the snowpack remains weak with depth hoar and facets.
Banff Visitor Safety dug a snow profile around Sunshine Ski Hill (Jan 19) for more details.
Weather Summary
Sat night: M winds from the southwest will continue overnight with alp temp lows of -8 . Up to 5cm of precip.
Sun: L to M winds from the southwest with alp temps around -8. Cloudy with scattered flurries of trace amounts of snow.
Mon-Tues: Cloudy with 30 percent chance of flurries. Temps just below freezing at TL. Trace amounts of snow with light winds from the SW
For more information, click here for the Mountain Wx Fx.
Terrain and Travel Advice
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Wind Slabs
Moderate to strong winds for the past several days have produced widespread wind effects and intermittent wind slabs in the alpine and exposed treeline. This includes a hard slab with the potential for wide propagation.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Loose Dry
Increased southwest winds may result in dry loose avalanches out of steep alpine terrain. Avalanches likely will be small but will be a concern if funneled into a terrain trap or gully.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 1.5
Deep Persistent Slabs
The base of the snowpack consists of weak facets, depth hoar, and the overlying crust continues to break down. Use caution in steep terrain, areas with wind slabs (step-down potential), large planar slopes, and thin to thick areas.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 3