Avalanche Forecast
Issued: Jan 7th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Deep Persistent Slabs and Wind Slabs.
wlewis,
Avalanche Canada
Danger ratings have dropped but conditions are still tricky with low confidence in buried weak layers.
Avoid terrain features where the snowpack varies from thick to thin, weak layers are more easily triggered here. Check out the new Forecasters' Blog for more details on managing this seasons challenging snowpack.
Summary
Confidence
Moderate
Avalanche Summary
Significant avalanche activity was reported throughout the Columbia's and Western Purcells from Monday January 1st to Thursday the 5th. Persistent and deep persistent slabs were naturally and human triggered up to size 3, failing on the weak layers described in the Snowpack Summary from 70-200 cm deep. Avalanches occurred on all aspects, and mostly between 1800 and 2500 m in elevation.
Avalanche activity has tapered off in recent days, a promising trend, however these layers are likely still reactive to human triggers and capable of producing large avalanches. Check out these MIN reports from Joss Mountain, & North McCrea Mountain for an idea of recent conditions and features of concern.
Small slabs in wind loaded features have also been triggered by riders, which have the potential of stepping down to these deeper weak layers.
Snowpack Summary
The upper snowpack consists of up to 50 cm of settling snow, with a small surface hoar layer found up to 10 cm deep. A crust may exist on sun affected slopes. Consistent southerly winds are redistributing snow into wind loaded features at higher elevations. New wind slabs may sit over the layer of surface hoar and/or crust.
The upper snowpack is generally settled and well-bonded, however buried weak layers in the mid and lower snowpack continue to be a concern although avalanche activity appears to be tapering off:
A layer of crust, facets and/or surface hoar buried around Christmas sits 40-70 cm deep.
A layer of large and weak facets from mid November sits near the ground.
This year's snowpack is weaker than usual, as described in our Forecasters' blog.
Weather Summary
Saturday Night
Cloudy with flurries possible. Moderate to strong southerly winds. Freezing level around 500 m.
Sunday
Cloudy with light snowfall, accumulations up to 2 cm. Moderate southerly wind. Alpine high of -3 °C. Freezing levels 800-1000 m.
Monday
Cloudy with light snowfall, accumulations of 5-10 cm. Moderate southerly wind. Alpine high of -3 °C. Freezing levels 800-1000 m.
Tuesday
Clearing skies. Freezing levels reach 600 m, alpine highs of -4 °C. Light southerly winds.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Persistent Slabs
A layer of surface hoar, facets and/or a crust sits 40 to 70 cm deep, which is a prime depth for human triggering. This layer has been most problematic around treeline and lower alpine elevations and has produced large avalanches.
Keep terrain selection conservative in these elevation bands and practice good travel habits to reduce your exposure.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. This layer has most recently been problematic in lower alpine elevations.
Avoid thin and rocky start zones where weak layers sit closer to the surface, riders are most likely to trigger an avalanche on this layer in terrain with shallow or variable snow depths.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Wind slabs can be found in west through east facing terrain - loaded by the southerly winds. Wind loading may sit over a layer of crust or surface, increasing reactivity.
Avalanches triggered in wind-loaded terrain have the potential to step down to deeper weak layers, creating larger than expected avalanches.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 8th, 2023 4:00PM
