Avalanche Forecast
Issued: Feb 2nd, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Persistent Slabs and Deep Persistent Slabs.
swerner,
Avalanche Canada
Strong winds combined with recent storm snow are creating dangerous avalanche conditions. Reactive storm slabs are widespread and sit above a complex snowpack, increasing the likelihood of triggering large and destructive avalanches.
Summary
Confidence
Moderate
Avalanche Summary
Avalanche activity will likely continue through Friday as the temperatures slightly rise and the winds ramp up redistributing and consolidating the 60-80 cm of recent storm snow.
On Wednesday, numerous natural and rider-triggered storm slabs and dry loose avalanches were reported up to size 1.5.
Last weekend, several very large (size 3 to 4) avalanches were triggered naturally on the basal facets. The avalanches were on all aspects and generally in alpine terrain between 1700 and 2900 m. See here for a video of a rider-triggered avalanche near Renshaw and another example here near Clearwater.
See more on the potential of triggering deeper weak layers Forecasters' Blog.
Snowpack Summary
60-80 cm of recent low-density storm snow has blanketed the region. The new snow accompanied by strong gusty winds overnight Thursday into Friday will likely form reactive storm slabs and wind slabs in lee terrain features. They will overly previously wind-affected snow from recent northeast wind, surface hoar in sheltered areas and faceted snow.
In the upper metre of the snowpack sits two layers of surface hoar crystals and/or a melt-freeze crust. The surface hoar is most likely found around treeline and lower alpine elevations. The melt-freeze crust is found up to 1800 m on all aspects and into the alpine on sun-exposed slopes.
Large and weak facets from November are near the base of the snowpack, which continue to produce very large avalanches in the region.
Weather Summary
Thursday Night
Cloudy with snow 5-10 cm. Ridgetop winds 30-80 km/h from the southwest. Treeline temperature -8 °C.
Friday
Cloudy with possible sunny breaks. Ridgetop wind 35 km/h and gusting to 70 km/h from the southwest. Treeline temperature -5 °C and freezing level 1300m.
SaturdayCloudy with light snow 5-10 cm. Ridgetop wind 15-30 km/h from the South. Treeline temperatures near -7 °C and freezing level 1200 m.
SundayCloudy with sunny periods and isolated flurries. Ridgetop wind mostly light with some strong 45 km/h gusts from the southwest. Treeline temperatures warming to -6 °C and freezing level 1500 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
- Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Problems
Storm Slabs
New snow combined with the strong southwesterly wind has formed reactive storm slabs, especially on leeward slopes that may see more loading from the wind. Dry loose avalanches and sluffing will likely be seen from steeper slopes and terrain features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Two surface hoar layers found in the upper 100 cm of the snowpack have been reactive in scattered areas around the region. Be especially cautious around steep openings within and near treeline elevations, especially where the recent storm snow has been wind affected.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. In the past week, this layer has produced very large avalanches that can travel far. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain, or by triggering a smaller avalanche that could step down to this layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 3rd, 2023 4:00PM
