Avalanche Forecast
Issued: Feb 26th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
cgarritty,
Avalanche Canada
Continuous snowfall and strong to extreme winds will maintain dangerous avalanche conditions in the region over the weekend. Stick to low angle, low consequence slopes and avoid exposure to overhead avalanche terrain.
Summary
Confidence
Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.
Weather Forecast
FRIDAY NIGHT: Becoming cloudy with isolated flurries and a trace of new snow, increasing in the morning. Winds becoming strong southwest.
SATURDAY: Cloudy with continuing flurries bringing up to 5 cm of new snow, continuing overnight. Strong to extreme southwest winds, continuing overnight. Alpine high temperatures around -7.
SUNDAY: Cloudy with continuing flurries bringing 5-10 cm of new and 2-day snow totals to 10-20 cm, continuing but easing overnight. Strong southwest winds, easing over the day. Alpine high temperatures around -10.
MONDAY: Cloudy with continuing flurries bringing about another 5 cm of new snow and 3-day totals to 15-25 cm, continuing again overnight. Strong to extreme southwest winds. Alpine high temperatures around -11.
Avalanche Summary
Evidence of a recent storm slab avalanche cycle to size 2 has been observed in the days since last weekend's storm. Heightened avalanche danger has been maintained through the week by subsequent bouts of elevated southwest wind. Slopes that have not avalanched remain a serious concern for human triggering potential, particularly where wind loaded.
This MIN report outlines conditions at the end of last weekend.Â
Snowpack Summary
60+ cm of snow from last weekend's storm rests on heavily wind affected and faceted snow in exposed terrain and perhaps a weak layer of surface hoar in sheltered areas, as reported here and here.Â
Although our best weather stations in the region are currently down, we have observations from Wednesday and again on Thursday night that describe a mix of strong southwest and northeast winds have been redistributing our aging storm snow into new wind slabs in exposed terrain. More strong to extreme southwest winds are forecast for Saturday.
The lower snowpack is strong around White Pass, but inland areas like the Wheaton Valley likely have a thinner and weaker structure.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
Problems
Wind Slabs
Elevated winds from both the northeast and the southwest have been observed transporting loose snow in the region through Thursday and Friday, with even more wind on tap for Friday night. Expect to find reactive new wind slabs on a wide range of aspects as you approach wind-exposed terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
60+ cm of aging storm snow rests on hard wind-affected snow, weak facets, and perhaps weak surface hoar in sheltered areas. This snow needs time to settle and stabilize before we can begin to trust it.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 27th, 2021 4:00PM
