Avalanche Forecast
Issued: Apr 14th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Deep Persistent Slabs and Loose Wet.
TH,
Avalanche Canada
Freezing levels will be on the rise through the weekend as a weather system threatens showers for Sunday.
Despite the recent natural avalanche cycle slowing down, expect avalanche hazard to increase through the weekend and keep the deep persistent slab problem at front of mind.
Summary
Confidence
Avalanche Summary
We have just come out of an avalanche cycle to size 4 which had many full-depth avalanches running full path.
Avalanche control Thursday on Mt. Bosworth produced storm slabs up to size 2.5 and on Mt Bourgeau produced several deep persistent slabs to sz 3.
On Wednesday avalanche control in Kootenay produced slides to size 3.5 with very wide propagations.
Snowpack Summary
Recent storm snow has settled to around 30cm above 2300m. This overlies sun crusts up to ridge top and faceted layers on shady aspects. Below 2300m, shallowly buried crusts lie over a previously isothermal snowpack following recent rain. New sun crusts are forming.
Several buried crusts are in the top 50-70 cm on solar aspects. The bottom of the snowpack remains facetted and weak.
Weather Summary
Clearing skies overnight Friday should bring a good freeze. SW winds will build to 30-40 km/h.
Saturday, scattered flurries will begin. Freezing levels will rise to 2000m plus and return to valley bottom overnight.
Sunday, winds increase to strong, 5-10cm of snow (rain?) is likely with freezing levels as high as 2500m.
Terrain and Travel Advice
- Keep in mind that human triggering potential persists as natural avalanching tapers off.
- If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
Problems
Storm Slabs
30-40cm of storm snow fell this past week forming widespread slabs in alpine and treeline areas. While these have started to settle out, expect human triggering in steep terrain especially with increasing temperatures, rain, or solar heating.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The basal facets, as well as mid-pack facets and crusts, remain a significant concern. Many large avalanches in the recent cycle initiated on, or stepped down to, these layers demonstrating the problem is both widespread and possible to trigger.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Freezing levels are on the rise through the weekend and while solar inputs may diminish on Saturday as the weather approaches, the potential for rain at lower elevations on Sunday, when the system arrives, is of equal concern.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Apr 15th, 2023 4:00PM
