Avalanche Forecast
Issued: Mar 17th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Wet and Deep Persistent Slabs.
wlewis,
Avalanche Canada
Watch for reactive slabs in wind loaded terrain. A layer of buried surface hoar is increasing reactivity and propagation.
Monitor snow conditions on sun baked slopes, wet avalanches become more likely in the afternoon as daytime temperatures rise and sun effect increases.
Summary
Confidence
Avalanche Summary
Slab avalanches were reported over the past few days, being triggered naturally, by riders, and by large loads like cornice falls and vehicles. The avalanches were small to large (size 1.5 to 2.5) and releasing within the 25 cm of recent storm snow in terrain at higher elevations, mostly around ridgelines. Most avalanches were thought to occur on the buried surface hoar layer.
Natural and rider triggered loose wet avalanches were also observed to size 1 from rising temperatures and sunshine.
Snowpack Summary
Around 15 to 25 cm of recent snow overlies large surface hoar crystals in terrain sheltered from the wind and sun, wind-affected snow in wind exposed terrain, and a hard melt-freeze crust on sun-affected slopes.
Southwest winds have created deeper and more reactive deposits on north to east facing terrain features near ridges. Warmer weather and sunny skies may moisten the snow surface on sun-exposed slopes and at low elevations.
The middle of the snowpack is strong and contains numerous hard crusts.
The lower snowpack is composed of weak basal facets. The layer has not produced recent avalanche activity, however it may become active again with any rapid change to the snowpack, such as rapid loading (heavy snowfall or rain) or prolonged and extensive warming. Avoiding thin and rocky slopes is still recommended. Cornices are also very large and a cornice failure could trigger this basal layer.
Weather Summary
Friday Night
Mostly clear skies as freezing levels drop to valley bottom. Moderate southerly winds.
Saturday
Sunny with moderate southerly winds. Freezing levels rise to 1500 m. Alpine high temperature -3 °C.
Sunday
Mostly cloudy with up to 2 cm of snow. Moderate to strong southeast winds. Freezing levels rise to 1000 m.
Monday
Light snowfall continues with cloudy skies and moderate southeasterly winds Freezing levels around 1000 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
Wind slabs may be found at higher elevations, particularly around ridgelines. Slabs may be particularly touchy where they sit on a weak layer of surface hoar crystals.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Rising freezing levels and sunny periods will create moist surface snow at low elevations and on sun affected slopes. Avoid steep sun-exposed slopes during the heat of the day, especially around rocks where warming will be amplified. Cornices may also weaken with daytime warming.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Weak, sugary faceted grains exist near the base of the snowpack. Riders are most likely to trigger this layer on steep, rocky slopes where the snowpack is shallow. The likelihood of avalanche activity on this layer will increase during periods of rapid change to the snowpack, such as heavy snowfall, rain, or rapid warming. Cornices are also very large at this time of year and a cornice failure could trigger this layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 18th, 2023 4:00PM
