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.
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Avalanche Canada
Unusual weather makes for unusual avalanche conditions: around 50cm of dry pow is on the ground ready to be picked up by the wind. If the wind strikes for even a few hours expect fat pillows of fresh windslab. An unusual "reverse loading" pattern will result form the north wind.
Summary
Confidence
Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.
Weather Forecast
Monday Night: Wind increasing to strong northwest. Treeline temperatures around -10 to -15 C. Light snow (north) or flurries (south) with up to 5 cm by morning.
Tuesday: Mix of sun and clouds, some of those clouds are low so good chance of sun at higher elevations.. Modrate to strong northwest wind. Treeline temperatures around -10 C. No snow.
Wednesday: Mostly sunny with increasing cloud in the afternoon. Strong northwest wind. Treeline temperatures around -10 C. No snow.
Thursday: Up to 5 cm with a short lived band of moisture blowing through on a strong northwest wind. Temperatures around -10 C.
Avalanche Summary
From the few reports we've received the upper snowpack is unconsolidated so loose dry avalanches (sluffs) have been the primary concern. This will change Tuesday with strong wind forecast: widespread and potentially deep windslabs are expected.
Snowpack Summary
With plenty of soft, light snow available for transport, expect wind slab formation at upper elevations Tuesday morning. A northwesterly wind direction means atypical cross-loading and reverse loading patterns.
20-40 cm now sits over a freezing rain crust below 1500 m and above this elevation it may rest on a layer of large surface hoar crystals. Our field team reported easy shears on this layer in their MIN report last week. You can see photos of the surface hoar prior to being buried by the storm in these MIN reports from Elk Mountain on Monday and Mt Kitchener on Tuesday.
The mid- and lower snowpack are generally well settled.
Terrain and Travel
- Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
- Avoid freshly wind loaded terrain features.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- Sheltered slopes at lower elevations will offer the best riding.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Wind Slabs
With plenty of soft, light snow available for wind transport, we expect to see wind slab formation in the alpine and open areas near treeline. A north or northwest wind means atypical cross-loading and reverse loading patterns.
Aspects: North East, East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 28th, 2021 4:00PM
