Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
The Mt. Field and Mt. Stephen avalanche closure zones are CLOSED on Wednesday, January 31, 2024 for avalanche control.
A natural avalanche cycle is ongoing with many avalanches up to size 2.5 in the last 48 hrs. Freezing levels climb again Wednesday keeping the avalanche danger high. Avoid avalanche terrain until things cool down.
Confidence
High
Avalanche Summary
Widespread avalanche activity has occurred over the past 48 hrs. Natural wet loose avalanches up to size 2 have been observed on all aspects below treeline and on some steep solar aspects at higher elevations. Natural and explosive triggered avalanches up to size 2.5 have been observed on all aspects at treeline and in the alpine failing on a variety of facet, crust and basal facet weak layers found in the snowpack. We expect this avalanche activity to continue on Wednesday.
Snowpack Summary
Rain and warm temperatures have soaked the snowpack up to 2200 m with moist surface snow even higher. Strong SW winds are creating wind slabs in alpine/treeline areas. Jan 19 facets from the cold snap are 10-30 cm deep, with the Dec 31 surface hoar/sun crust 30-50 cm deep. Two deteriorating crusts (Dec 22nd and Dec 5th) exist in the mid-pack up to 2300 m. The lower snowpack is comprised of weak facets and depth hoar in most areas. Treeline snow depths range from 70 -120 cm.
Weather Summary
After a cooling trend and some light flurries possible on Tuesday night, freezing levels are expected to climb as high as 2700 m by Wednesday afternoon with strong winds out of the SW. A mix of sun cloud will accompany the warm weather with sunny breaks increasing the effect of the warm weather on the snowpack.
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Terrain and Travel Advice
- Avoid areas where the snow feels stiff and/or slabby.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Avalanche Problems
Loose Wet
Rain to 2200 m and warm temperatures have saturated the snowpack below treeline. This has resulted in widespread wet loose avalanches happening in steep terrain and gullies. The snowpack below treeline will remain weak and saturated until temperatures cool.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2
Persistent Slabs
Recently formed slabs sit on facets produced during the January cold snap, as well as surface hoar/suncrust found below these facets. This is an unstable combination and we've seen evidence of multiple avalanches on this layer over the last week. Avoid steep, open slopes until it cools off again.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2.5
Deep Persistent Slabs
The base of the snowpack consists of weak facets and depth hoar, and the overlying midpack and crusts continue to break down. Human and natural triggering of these basal facets in steep terrain, large planar slopes, and thin to thick areas remains likely.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1.5 - 2.5