Avalanche Forecast
Issued: Nov 20th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
Tereza Turecka,
Strong west to south-west winds expected to add load to the recently formed wind slabs and persistent slab as there is still a lot of snow available for transport.
Summary
Weather Forecast
Sunday: Cloudy with isolated flurries. Precip: Trace. Alp temperature: High -7 C. Ridge wind southwest: 20-35 km/h.Monday: Snow: 9 cm. Alpine temperature: Low -10 C, High -5 C. Wind southwest: 20-40 km/h. FL: 1400 metres.Tuesday: Cloudy with scattered flurries: 4 cm. Alp temp: Low -13 C, High -7 C. Wind west: 15 km/h gusting to 45 km/h.
Snowpack Summary
Surface hoar of up to 4mm observed on all aspects up into alpine prior to the current strong W- SW winds. The storm snow has now formed persistent slab particularly in wind loaded features. A 2cm thick crust 80cm down is found up to 2500m or higher. Weak facets below the crust result in sudden collapse test results.
Avalanche Summary
Friday's team observed two size 2 persistent slab avalanches on windloaded features in the alpine and treeline. On Wednesday numerous avalanches up to size 3.5, generally from steep alpine features, were noted. They occurred during or at the end of the Nov 13-15th storm. One 800m wide avalanche was caused by explosives at tree-line on Tuesday.
Confidence
Problems
Persistent Slabs
60-80cm of storm snow from Nov 13-15th has settled into a persistent slab condition. Field tests are showing sudden collapse on a crust down 50-80cm over weak facets. The snowpack is still at its infancy and the prudent thing to do is be cautious.
- Use caution on open slopes and convex rolls
- Avoid thin rocky or unsupported terrain features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Watch for wind loading at ridge tops and in the alpine with recent West and SW winds. Strong winds are expected to persist into Monday with a lot of snow still available for transport.
- Use caution in lee areas. Recent wind loading have created wind slabs.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 21st, 2021 4:00PM
