Avalanche Forecast
Issued: Jan 1st, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
ahanna,
Avalanche Canada
If venturing out in search of dry powder up high, avoid wind loaded features and stick to low angle terrain free of overhead exposure. The fresh storm slab will be especially sensitive to human triggering, as well as solar triggering if the sun comes out on Thursday.
Summary
Confidence
Weather Forecast
Wednesday night: Scattered flurries accumulating up to 5 cm, moderate wind from the west, alpine low temperature around -4 C, freezing level dropping to valley bottom.Thursday: Mix of sun and cloud with isolated flurries, moderate wind from the west, alpine temperature dropping to -7 C.Friday: Scattered flurries with trace accumulation, moderate wind from the southwest, alpine high temperature rising to +1 C, freezing level rising to 2200 m.
Saturday: 5-10 cm of snow, moderate wind from the southwest, alpine high temperature cooling to -4 C, freezing level dropping to valley bottom.
Avalanche Summary
Many large (size 2-3) storm slab avalanches, both natural and explosive triggered, were reported on Wednesday. Expect to see continued natural storm slab activity if the sun comes out on Thursday and with the rapid warming on Friday.
It's now been a week since a widespread cycle of very large deep persistent slab avalanches occurred in response to the storms prior to Christmas. This deep persistent weakness has since been trending toward dormancy. The new snow load and large avalanches on Wednesday were a great test. An absence of reports of storm slab avalanches stepping down to the deeper layers indicates that the deep persistent slab may not be a pertinent avalanche problem at this time.
Snowpack Summary
30 cm of new snow has fallen amid mild temperatures resulting in heavy, moist surface snow at lower elevations. Forecast moderate wind in the alpine is likely loading lee features in high, wind exposed areas. Below 1700 m a hard rain crust is becoming buried. Hard snow sits above weak snow and crusts near the bottom of the snowpack (100-170 cm deep).This weak snowpack structure resulted in very large avalanches prior to Christmas. This layer has since been trending toward dormancy.
Terrain and Travel
- Don't let the desire for deep powder pull you into high consequence terrain.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- Brief periods of sun could quickly initiate natural avalanche activity.
Problems
Storm Slabs
Recent snow combined with moderate winds will result in reactive storm slabs, sensitive to human triggering. Pay attention to steep south facing slopes if the sun comes out on Thursday. New snow is particularly sensitive to solar triggering when the first rays of sun hit.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 2nd, 2020 5:00PM
