Avalanche Forecast
Issued: Dec 27th, 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
Make conservative decisions and avoid wind loaded features. The new wind slab likely won't bond well to the surfaces below.
Summary
Confidence
Weather Forecast
Monday night: no new snow expected. Low of -14 at 1200m with moderate to strong northwest winds. Possibility of temperature inversion with colder temperatures in the valley bottom.
Tuesday: skies clearing in late afternoon and no new snow expected. winds will be moderate from the northwest with a high of -15 at 1200m.
Wednesday: A mix of sun and cloud with the possibility of some light flurries. Strong northwest wind. High of -10 at 1200m.
Thursday: clear with no new snow expected. Moderate northwest winds with a high of -18 at 1200m.
Avalanche Summary
We suspect that some natural wind slab avalanches would have released on Monday morning.
On Wednesday our field team observed several natural avalanches up to size 2 on Log Cabin and above Fraser Chutes. These avalanches were on cross-loaded east and south east facing slopes above treeline.
Snowpack Summary
up to 15cm of new snow has formed wind slab on south and east aspects. These new wind slabs overlie old faceted hard slab. We suspect the new wind slab will not bond well to these surfaces. North and west aspects are generally scoured.
Surface hoar may exist just below the surface 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.
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 28th, 2021 4:00PM
