Avalanche Forecast
Regions: Little Yoho.
Major warming event for Tuesday - freezing levels to 3500m under sunny skies. Climbers and skiers should avoid avalanche terrain. Avalanche control is planned for the Bosworth, Stephen and Mt. Field paths - no access to these areas on Tuesday.
Weather Forecast
The most significant warming event of the winter will occur on Tuesday, as freezing levels are forecast to reach 3500 m and temperatures in the high alpine could reach +5 - warmer in sheltered areas when combined with clear skies and sunshine. Strong west winds (50 km/hr) in alpine areas.
Snowpack Summary
A 50-100 cm slab now overlies the January 6 weak layer of surface hoar, facets and sun crust and snowpack tests indicate an unstable bond between the two. Extreme warming and sunshine forecast for Tuesday will provide the necessary trigger, and slab avalanches are likely in many locations along with cornice failures and wet sluffs in gullies.
Avalanche Summary
The past 48 hours saw a widespread avalanche cycle of natural and human triggered avalanches up to size 3. Evidence of recent avalanches exists in many avalanche paths - most are slabs that failed 50-70 cm deep on the Jan 6 weak layer. Today we observed one fresh size 2 on Mt Whymper on a south facing, windloaded slope at 2400 (crown depth ~100 cm)
Confidence
Freezing levels are uncertain on Tuesday
Avalanche Problems
Persistent Slabs
Expect this problem to produce avalanches on Tuesday, and avoid exposure to avalanche terrain as these will be large avalanches with potentially significant consequences.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible - Likely
Expected Size: 2 - 3
Loose Wet
Expect wet snow sluffs and rockfall due to the wet snow - most problematic in low elevation gullies and all south and west facing terrain. Ice climbers should be particularly alert for this.
- Avoid ice climbs exposed to steep rocky terrain on solar aspects during the middle of the day.
Aspects: North, North East, East, South East.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2
Cornices
The big warmup will weaken cornices and they can be expected to fall off spontaneously. Avoid overhead exposure to any cornices, but if you must then consider the runout distance and minimize your exposure time.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Possible - Likely
Expected Size: 1 - 3