Avalanche Forecast
Issued: Feb 3rd, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
wlewis,
Avalanche Canada
Wind slabs continue to be a concern at higher elevations.
Approach steep open slopes at treeline and below with caution. A buried surface hoar layer may become may be reactive to human triggers. Watch for signs of instability as you travel.
Summary
Confidence
Moderate - We are confident about the possible sizes of avalanches, should one release; what is less certain is the likelihood of triggering. Uncertainty is due to the extreme variability of wind effect on the snowpack.
Weather Forecast
Light snowfall is forecast for Friday. Temperatures rise and skies clear for the weekend.
THURSDAY NIGHT: Mostly cloudy. Moderate westerly winds. Freezing level at valley bottom. Isolated flurries possible.Â
FRIDAY: Cloudy with flurries deliver less than 5 cm by the end of the day. Strong westerly winds. Freezing level rises to around 1000 m. Alpine high of -5.
SATURDAY: Mostly clear with moderate westerly winds. Freezing levels rise around 1500 m, with alpine highs of -3. Moderate westerly winds.Â
SUNDAY: Mostly clear with moderate westerly winds. Freezing levels rise to 2000 m with a high of 0.Â
Avalanche Summary
Loose dry activity has been noted over the last few days, to size 1 and 1.5. Natural slab activity was last observed on Monday to size 2. Small storm slabs were also triggered by ski cutting and explosives on Monday.
Shooting cracks and whumpfing have been reported by industry operators and in several MIN reports in specific areas. While the surface hoar is only found in specific areas, it is sensitive to human triggers.
Snowpack Summary
At lower elevations 20-40 cm of storm snow sits over a melt freeze crust observed to 2000 m. In sheltered terrain, a layer of large surface hoar crystals may sit immediately above the crust, sensitive to human triggers.
At higher elevations the storm snow has been redistributed into pockets of wind slab by strong westerly winds. A thin melt freeze crust extends into the alpine on solar aspects. This crust may sit on the surface in exposed terrain, or below wind deposited snow in sheltered areas increasing reactivity.
The early December crust/facet persistent weak layer is now 100-200 cm deep. This layer produced numerous very large avalanches in January, and is now considered dormant. We will continue to track this layer of concern and expect it will wake up again with major warming or a large storm event. This recent forecaster blog goes into more details on the layer.
Terrain and Travel
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be alert to conditions that change with elevation and wind exposure.
Problems
Persistent Slabs
Fresh snow sits over a large and sensitive surface hoar. On south facing aspects this may sit on a crust. Treat open slopes at treeline and below with caution - they may be more reactive and produce larger avalanches than you expect. Shooting cracks or whumpfing are clear signs to keep terrain choice conservative.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Wind Slabs
Fresh wind slabs may build with continued strong westerly winds and new snow. Expect reactivity where they overly a smooth crust, or a weak surface hoar layer in sheltered terrain features.
Look for wind loading in unusual places, as direction has varied from northwest to southwest and stronger wind speeds may load mid slope features.
Aspects: North, North East, East, South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 4th, 2022 4:00PM
