Avalanche Forecast
Issued: Feb 22nd, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
shorton,
Avalanche Canada
Human triggered avalanches are possible at all elevations, watch for signs of instability and gather information before exposing yourself to avalanche terrain.
Summary
Confidence
Weather Forecast
A few days of cool dry weather.
MONDAY NIGHT: Scattered flurries with 5-10 cm of snow, strong west wind at ridgetops, treeline temperatures drop to -10 C.
TUESDAY: Mix of sun and cloud, light wind with some moderate gusts from the west, treeline temperatures around -8 C.
WEDNESDAY: Sunny, light wind, treeline temperatures around -8 C.
THURSDAY: Scattered flurries with 5-10 cm of snow, moderate southwest wind, treeline temperatures around -8 C.
Avalanche Summary
Steady pulses of snow between Wednesday and Saturday resulted in surprisingly little avalanche activity, but by Sunday there were several reports of size 1-1.5 storm and wind slab avalanches. These avalanches were mostly 20-30 cm thick and were triggered both naturally and by humans. Explosive control produced a few larger (size 2) avalanches.
There were many reports of human triggered persistent slab avalanches during the first two weeks of February. These avalanches failed on a surface hoar layer that is now 50-100 cm deep and is most prevalent at treeline elevations. There were also two very large explosive triggered avalanches in the Bonningtons in the past month that stepped down to the early December crust (most recently on Feb 9). These deeper instabilities have been trending towards being unreactive, however occasional snowpack tests suggest they may still be possible to trigger in some areas.
Snowpack Summary
25-50 cm of recent snow is likely heavily wind affected in open terrain while in sheltered terrain it could either be low density powder or heavy and slabby. The main persistent layer of concern is a combination of surface hoar, facet, and crust layers that formed in January that are now buried 50-100 cm deep. An early season crust near the bottom of the snowpack has periodically produced avalanches in thinner snowpack areas. These persistent layers have appeared to gone dormant in the past week, but steep open slopes should still be assessed carefully.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
Problems
Storm Slabs
25-50 cm of recent snow, along with strong southwest wind, has likely left reactive slabs on steep and wind loaded slopes.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A persistent weak layer 50-100 cm deep continues to show reactivity in snowpack tests, despite not producing avalanches in the past week. This surface hoar/crust interface may remain human triggerable in steep convex features at treeline and potentially steep alpine features where it presents as a crust.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 23rd, 2021 4:00PM
