Avalanche Forecast
Issued: Mar 2nd, 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.
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Avalanche Canada
Sunshine and wind loading will be the main contributors to avalanche danger. In the northern Purcells there remains a concern about triggering large persistent slab avalanches.
Summary
Confidence
Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.
Weather Forecast
TUESDAY NIGHT: Mostly cloudy, moderate southwest wind, treeline temperatures drop to -8 C.
WEDNESDAY: Mix of sun and cloud, moderate southwest wind, freezing level climbs to 1700 m with treeline temperatures around -3 C.
THURSDAY: Sunny, light south wind, freezing level climbs to 1900 m with treeline temperatures around -1 C.
FRIDAY: Sunny, light south wind, freezing level climbs to 1900 m with treeline temperatures around -1 C.
Avalanche Summary
Avalanche activity has been on decline over the past week, with a few reports of size 1-2 storm and/or wind slabs each day. On Monday reports were limited to small (size 1) wind slab avalanches on north and east aspects.
However, there have still been a few notable avalanches in the northern Purcells over this period including a large human-triggered persistent slab avalanche in the east Quartz Creek on Saturday (MIN report can be viewed here) and a few remotely triggered avalanches on Wednesday that likely failed on the recently buried persistent weak layer (MIN report can be viewed here). Recent persistent slab activity appears to be isolated to the northern end of the Purcells.
Snowpack Summary
Strong southwest wind has likely formed wind slabs in open terrain, while sheltered terrain has 15-40 cm of settling powder. This recent snow sits on a layer of facets that formed during the last cold snap, which could develop into a weak layer in the future. Surfaces are likely starting to melt and freeze on southern slopes and at lower elevations.
Persistent weak layers have been most active in the northern end of the Purcells where a buried layer of surface hoar that formed in late January is 40-80 cm deep and an older surface hoar layer is 60-120 cm deep at treeline. These layers may exist as a combination of facets or crusts at other elevations. Recent observations suggest these layers have been less problematic as you move further south.
Additional weak layers may exist near the base of the snowpack in steep rocky areas where the snowpack is thin.
Terrain and Travel
- Be especially cautious as you transition into wind affected terrain.
- Minimize exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
Strong southwest wind has likely left reactive slabs in steep open terrain at alpine and treeline elevations, especially on north and east aspects.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Persistent slab avalanches are most likely in the northern Purcells where there has been recent avalanche activity on a 40-80 cm deep layer of surface hoar, facets, and/or crusts.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 3rd, 2021 4:00PM
