Avalanche Forecast
Issued: Feb 1st, 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
Treat open slopes at treeline and below as suspect, new snow sits on a weak surface hoar layer. Watch for signs of instability like shooting cracks and whumpfing.
Wind slabs will continue to form at higher elevations as westerly winds strengthen.
Summary
Confidence
Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.
Weather Forecast
Arctic air brings cold temperatures, wind and little chance of snow until Friday.
TUESDAY NIGHT: Scattered flurries continue. Light to moderate N winds. Freezing level at valley bottom.Â
WEDNESDAY: A mix of sun and cloud. Moderate W winds. Freezing level at valley bottom. Alpine high of -15.
THURSDAY: A mix of sun and cloudy. Moderate W winds with strong gusts. Freezing level at valley bottom. Alpine high of -7.
FRIDAY: Cloudy. Moderate W winds with strong gusts. Freezing level at valley bottom. Alpine high of -4. Scattered flurries.Â
Avalanche Summary
The recent storm produced a natural avalanche cycle to size 2. Small storm slabs and loose dry avalanches were also triggered by ski cutting and explosives on Monday.Â
Shooting cracks and whumpfing were reported in the storm snow yesterday, indicating sensitivity in the buried surface hoar to human triggers. A Lizard-Flathead MIN report noted shooting cracks and whumpfing as well during their travel.
Snowpack Summary
At lower elevations up to 30cm of storm snow sits over a thick melt freeze crust, present up to 2000m. In sheltered terrain, a widespread layer of large surface hoar crystals sits immediately above the crust.
At higher elevations the storm snow is being redistributed by moderate to strong westerly winds, over a snow surface that was previously heavily wind affected. A thin melt freeze crust extends into the alpine on solar aspects. This crust may sit on the surface or below wind deposited snow.Â
The early December crust/facet persistent weak layer is now 100-200 cm deep. This layer produced numerous very large avalanches during the third week of January but is now considered dormant after a week of cold, dry weather. While this layer is not currently considered a front page avalanche problem, we continue to track it 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
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Wind slabs may be poorly bonded to the underlying crust.
Problems
Persistent Slabs
Fresh snow sits over a large and sensitive surface hoar layer. Treat open slopes at treeline and below with caution - they may be more reactive and produce larger avalanches than you expect.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Wind Slabs
Fresh reactive slabs may form over a smooth crust, and on a weak surface hoar layer in sheltered terrain features.
The snow came with southwest winds, and winds have now shifted to the northwest - expect wind slabs on most aspects.
Aspects: North, North East, East, South East, South, South West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 2nd, 2022 4:00PM
