Avalanche Forecast
Issued: Feb 18th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Persistent Slabs and Deep Persistent Slabs.
jsmith,
Avalanche Canada
Forecast snow and wind on Sunday will build reactive storm slabs. Large, natural avalanches may occur at upper elevations and human-triggered avalanches are expected at all elevations.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
Summary
Confidence
Avalanche Summary
Forecast snow and wind on Sunday will build reactive storm slabs. Large, natural avalanches may occur at upper elevations and human-triggered avalanches are expected at all elevations.
On Friday, a naturally triggered size 2 persistent slab that likely failed on a crust down around 100 cm was reported on a west aspect below treeline near Joss mountain.
Additionally, natural and human triggered wind slabs were reported up to size 2.5
Snowpack Summary
5-15 cm of new snow on Friday night brings recent snowfall totals to 40-60 cm. The recent snow is settling into storm slabs that will be most reactive where either wind has stiffened the snow or they overlie a layer of recently buried surface hoar.
Forecast snow and wind on Sunday will build reactive storm slabs. Large, natural avalanches may occur at upper elevations and human-triggered avalanches will be likely at all elevations.
The mid-pack is generally well consolidated with a few operations reporting continued snowpack results on a spotty surface hoar layer down roughly 80 cm. Reports of large avalanches involving various layers of surface hoar/crusts and facets within the mid-pack depth are sporadic but are a reminder of the complicated snowpack across this region.
In the lower snowpack, a layer of large and weak facets from November near the base of the snowpack is slowly gaining strength but there continues to be low confidence in this layer. Large destructive avalanches are the result of this layer being triggered.
Weather Summary
Saturday night
Snow; 5 to 10 cm / Moderate west ridgetop wind / Low -10 °C / Freezing level valley bottom.
Sunday
Snow; 10-25 cm; another 10-20 cm Sunday night / Strong west ridgetop wind / High -2 °C / Freezing level 1000 m.
Monday
Cloudy with flurries; 3-5 cm / Light northwest ridgetop wind / High of -3 °C / Freezing level 800 m.
Tuesday
Cloudy with flurries; 5-10 cm / Light southeast ridgetop wind / High of -10 °C / Freezing level valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
- Avoid all avalanche terrain during periods of heavy snowfall.
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Use small low consequence slopes to test the bond of the new snow.
Problems
Storm Slabs
Forecast snow and wind on Sunday will build reactive storm slabs. Large, natural avalanches may occur at upper elevations and human-triggered avalanches are expected at all elevations.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Problematic weak layers are becoming spotty across the region, however recent large persistent slab avalanche observations continue to trickle in reminding us that these layers remain a concern in this region. Recent avalanches have been triggered by a mix of large loads like cornices.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. This layer continues on a sporadic basis to produce very large avalanches that can travel far. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain, or by triggering a smaller avalanche that could step down to this layer. Cornices will continue to grow with new snow and wind and could be the large load needed to trigger deep persistent weak layers. Your best defense is to stay diligent in choosing low-consequence terrain away from overhead exposure.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 19th, 2023 4:00PM
