Avalanche Forecast
Issued: May 5th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Storm Slabs and Cornices.
mconlan,
Avalanche Canada
Cariboos, Kootenay Boundary, Lizard-Flathead, North Columbia, North Rockies, Purcells, South Columbia, South Rockies, Blue River, Clearwater, McBride, Premier, Quesnel, Sugarbowl, Clemina, Esplanade, Jordan, North Monashee, North Selkirk, Shuswap, Badshot-Battle, Central Selkirk, Goat, Gold, Kokanee, North Okanagan, Retallack, Valhalla, Whatshan, Dogtooth, East Purcell, Moyie, St. Mary, West Purcell, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, South Okanagan, Ymir, Akamina, Flathead, Lizard, Bull, Crowsnest North, Crowsnest South, Elkford East, Elkford West, Kakwa, McGregor, Pine Pass, Renshaw, Robson, Tumbler, Glacier.
The snowpack needs time to adjust to last week's intense warming. Be aware of the various avalanche problems that still exist.
Summary
Confidence
Moderate
Avalanche Summary
An avalanche cycle of large to very large (size 2 to 4) wet loose and slab avalanches, cornice failures, and deep persistent slab avalanches occurred over much of the region within the past two weeks. The likelihood of triggering may decrease while the snowpack experiences lower freezing levels and cloudy skies.
Snowpack Summary
A moist snow surface is expected below the rain-snow line, which will freeze into a melt-freeze crust overnight. Any snow that accumulates in the high alpine will build onto a hard melt-freeze crust.
The intense heat from the past two weeks moistened the snowpack. The warming reawakened weak layers, including weak snow above crusts buried in late March (50 to 100 cm deep) and the weak basal facets found at the bottom of the snowpack.
The snowpack is quickly diminishing below treeline, but large avalanches could release at higher elevations and run into valley bottoms.
Weather Summary
Saturday sees a freezing level decline to around 2500 m by late afternoon with mostly cloudy skies and periods of light rain. Sunday and Monday's freezing level is between 2000 m and 2500 m with mostly cloudy skies and periods of rain or snow in the high alpine.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Watch for fresh storm slabs building throughout the day.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Avoid steep slopes when air temperatures are warm, it is raining, or solar radiation is strong.
- Minimize exposure to overhead avalanche terrain, large avalanches may reach the end of runout zones.
Problems
Deep Persistent Slabs
Layers of concern include weak snow above hard crusts buried about 50 to 100 cm deep and weak facets near the bottom of the snowpack. Human triggered avalanches are most likely in steep, shallow, and rocky terrain, where the snowpack is relatively thin.
Resulting avalanches could travel far and even into snow-free valleys. For this reason, recognizing and avoiding areas with large overhead avalanche slopes, even if they are out of sight, is very important.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
New slabs may form in the alpine over the weekend. Use caution if you find more than 15 cm of recent snow.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Cornices
Cornices are large at this time of year and will become more prone to fail as they warm up with spring weather. Stay well back from them when on ridgelines and limit your exposure when travelling on slopes below them, as their release is unpredictable. Cornice falls could trigger very large slab avalanches on slopes below them.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: May 6th, 2023 4:00PM
