Avalanche Forecast
Issued: Dec 28th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
TRettie,
Avalanche Canada
Avoid wind loaded pockets at all elevations and seek out sheltered terrain where good riding could still be found. Wind slabs will still be sensitive to rider triggering.
Summary
Confidence
Weather Forecast
Tuesday night: temperature inversion with -7 at 1200m and a low of -20 at valley bottom. wind in the alpine will be light to moderate from the southwest. No new snow expected.
Wednesday: Moderate to strong northwest winds in the alpine with 5cm of new snow. Temperatures around -8.
Thursday: clear with no new snow expected. Another temperature inversion is possible, -12 at 1500m and -20 at valley bottom. Light winds.
Friday: strong southwest winds with light snow all day. High of -10 at 1500m.
Avalanche Summary
No new avalanches have been reported in the last few days. If you are out in the mountains please consider filling out a Mountain Information Network repport.
Snowpack Summary
Wind slab can be found at all elevations on east and south aspects. North and west aspects are generally scoured but periods of southwest winds could create wind slab on cross loaded features.
Surface hoar may exist down 20cm at 1300m and below. It is likely only a problem where wind slab has formed above it.
The lower snowpack is made up of weak sugary snow. An avalanche at this interface is most likely to be triggered in shallow areas or with a large impact like a cornice fall or surface avalanche.
Terrain and Travel
- Keep your guard up at lower elevations. Wind slab formation has been extensive.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Problems
Wind Slabs
New wind slabs on south and east aspects will likely not bond to the old hard slab and faceted surfaces below. Sensitivity to triggering will be greatest near ridge crests and isolated areas where slabs have formed over surface hoar in the treeline. Periods of south west winds could have created wind slab on cross loaded features on north and west aspects.
Aspects: East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Although the crust associated with this layer has largely decomposed, the weak sugary crystals at the base of the snowpack remain. The bridging affect of the wind hammered upper snowpack is making it harder to trigger this layer but now is not the time to become complacent. When managing hard slab on top of facets, try to think in terms of consequences just in case of a surprise. "If I trigger an avalanche here, what are the consequences? Will the avalanche be large? Are there terrain traps?"
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 29th, 2021 4:00PM
