Avalanche Forecast
Issued: Dec 26th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Dry and Deep Persistent Slabs.
Garth Lemke,
Happy Holidays to everyone from Jasper Visitor Safety team!
Summary
Weather Forecast
Monday will be a mix of sun and cloud, no new snow, -22C and Westerly light winds. Tuesday will bring sun and flurries, -30 to -20 C, and light Northerly ridge winds. Wednesday will be similar to Tuesday.
Snowpack Summary
35cm of snow arrived Dec 22-23 with moderate to strong SW winds. Wind slab developed in the alpine and on exposed terrain features at treeline. The winds have shifted Northerly so expect reverse loading. The mid-pack is supportive with an exception of a weak rain crust 30-40 cm down found up to 1950m. Cold temperatures will accelerate faceting.
Avalanche Summary
Friday's avalanche control produced numerous 30cm thick wind slabs up to size 2 on wind loaded open tree line features. One result buried the road 2m deep for a 100m. Surprisingly, explosives did not trigger the deeper instabilities. Numerous loose dry explosive triggered and natural activity also occurred up to size 1.5. No patrols since 24th.
Confidence
Due to the number of field observations
Problems
Wind Slabs
Up to 35cm of new snow Dec 22-23rd with moderate to strong winds created wind slabs on lee and cross loaded features. Winds have shifted Northerly so expect reverse loading patterns. A rain crust 30cm down is a suspect weak layer in BTL.
- Watch for stiffer feeling snow. Avoid areas that appear wind loaded.
- Use caution in lee and cross-loaded terrain near ridge crests.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Dry
A Dry loose problem persists with 35cm of new snow from Dec 23rd and ongoing accumulations from flurries. Extra vigilance is warranted in steep terrain, ice climbs, and gully terrain traps where small avalanches can build into significant volumes.
- Be careful of loose dry power sluffing in steep, confined or exposed terrain.
- Avoid travelling on ledges and cliffs where sluffing may have severe consequences.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
This problem, although stubborn, persists in isolated alpine terrain and may initiate with a large trigger or rapid loading. Use extra caution in thin areas were humans are most likely to trigger this high consequence layer.
- Use caution in thin snowpack areas.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 27th, 2021 4:00PM
