Avalanche Forecast
Issued: Nov 26th, 2020 4:02PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
Ian Jackson,
Good skiing exists in sheltered areas along the divide. The hazard may be higher than forecasted in eastern areas where winds and temperatures are forecasted to be highest
Summary
Weather Forecast
A big wind event Friday dominates the weather. Chinook conditions east of the divide with warm temperatures and strong westerly winds. Temperatures will stay cooler along the divide, but expect wind. Friday night and saturday we may see up to 15 cm of new snow with higher amounts to the north and winds easing slightly. Sunday looks cold and drier
Snowpack Summary
10-20cm of new snow, along with strong W-SW winds has created windslabs at treeline and above. The Nov 5 facet/crust combo is down 50-80 cm and producing variable test results from easy to hard, but 'sudden' in fracture character. The Nov crust extends up to 2500 m on N aspects and higher on solar aspects. Snow depths at treeline are 70-130 cm.
Avalanche Summary
New windslabs were particularly reactive in the Sunshine area with ski patrol triggering avalanches to size 2.5 with explosives. None of these stepped down to the Nov. 5th crust, but some impressive propagations in the new snow.
Lake Louise area saw less reactivity, although windslabs were widespread in the alpine.
Confidence
Wind effect is extremely variable
Problems
Wind Slabs
Continued strong Westerly winds have created windslabs in the alpine and at treeline. Results in the Sunshine area on Thursday showed the potential for wide propagations.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The deeper Nov.5 crust has facets growing above and below it, and exists up to 2500m on shady aspects and higher on solar aspects. New load from recent winds may make this layer more sensitive
- Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
- Be aware of thin areas that may propogate to deeper instabilites.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 27th, 2020 4:00PM
