Avalanche Forecast
Issued: Jan 6th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Persistent Slabs.
TH,
Avalanche Canada
Forecasters remain very concerned about the potential for human triggering. The deep persistent slab problem in particular has shown its potential for long propagation and remote triggering. Keep the slope angle mellow and the slope size small.
Summary
Confidence
Moderate
Avalanche Summary
Sunshine Village reported a few natural size 2 slabs on nearby Mt Brett. Jasper national park reported a sz 2.5 running to valley bottom off of Mt Kitchener
Snowpack Summary
10-20cm of soft surface snow sits over a generally weak midpack. The December 17 surface hoar and facet persistent layer is down 25-60cm. The November 16th and November 25 deep persistent layers of facets, depth hoar, and/or crusts are found near the base of the snowpack. Both of these problem layers show moderate to hard snowpack test scores of a sudden character.
Weather Summary
Friday night SW winds 40-50km/h will continue in the alpine with a low of -15C at treeline. Saturday will see a high of -5-10C at treeline with alpine winds diminishing in the PM to 20-30kmk/h. Saturday night will see a low of -12C. Trace amounts of snow and mainly cloudy skies closer to the divide through the period.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
- Use careful route-finding and stick to moderate slope angles with low consequences.
Problems
Deep Persistent Slabs
The lower snowpack is very weak with the mid and upper snowpack forming an overlying slab in many areas treeline and above. This weak basal layer is uniform across most of the terrain and has shown the potential for long propagations and remote triggering. Unlike most of the BYK region we have seen slab properties below treeline in Little Yoho.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Slabs 25-60cm thick sit over the December 17 layer formed by the facets that were on the surface during the prolonged deep freeze. When initiated, these slabs have often stepped down to deeper layers. Unlike most of the BYK region we have seen slab properties below treeline in Little Yoho.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 7th, 2023 4:00PM
