Avalanche Forecast
Issued: Dec 29th, 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.
jleblanc,
Avalanche Canada
Assess snow surface as you venture out. If you see any signs of instability, choose a low angle slope and pick a line where the snow is deepest.
Summary
Confidence
Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack.
Weather Forecast
A system, approaching from the north, is passing throughout Yukon Wednesday, with light amounts of snow but strong northerly winds. On Thursday, an arctic ridge of high pressure will re-establish itself, leading to another clear and cold day heading into Friday. The next round of snow is expected Saturday.
WEDNESDAY NIGHT: Lingering flurries / Moderate to strong north winds in the alpine / Low of -20
THURSDAY: Clear / Moderate northwest winds in the alpine / High of -18
FRIDAY: Flurries all day / Strong southwest winds in the alpine / High of -14
SATURDAY: Snow 10 cm / Strong southwest winds in the alpine / High of -12
Avalanche Summary
On Wednesday, the poor visibility restricted observations in the alpine.
No new avalanches have been reported in the last few days.Â
If you are out in the mountains, please consider filling out a Mountain Information Network repport.
Snowpack Summary
On Wednesday, the region received about 5Â cm of new snow along with southwest winds. This new snow has covered hard surfaces such as sastrugi, old wind slabs or recently scoured slopes in the alpine.Â
At treeline, the wind also affected the surface, but pockets of powder can be found. All this snow will get redistributed with the incoming northerly winds, creating cross-loading.Â
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.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
Freshly formed wind slabs will likely not bond to the old hard slab and faceted surfaces below. Sensitivity to triggering will be greatest near ridge crests. Shifting winds are prone to form wind slabs on cross-loaded features on various slopes.
Aspects: North, North East, 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 30th, 2021 4:00PM
