Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Mar 2nd, 2021–Mar 3rd, 2021

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

Purcells.

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.

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

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.