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Avalanche Forecast

Archived

Nov 26th, 2021–Nov 27th, 2021

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

Regions

North Rockies.

The break from storms may not be long enough to explore new terrain. Watch for new reactive slabs as the next wave arrives this afternoon.

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

The see-saw weather cycle continues. Clearer, colder, and calmer weather will shift to wet, warm, and windy this afternoon, and we'll do it all again next week.

FRIDAY NIGHT: Overcast. Freezing level falls to valley bottom. Strong southwest wind. No precipitation expected.

SATURDAY: Broken cloud cover with possible sunny periods. Freezing level starts at valley bottom and rises to 1500 m through the day. Alpine low -10. Moderate to strong southwest wind. 5-10 cm snow expected.

SUNDAY: Overcast. Freezing level 1600 m. Strong to extreme southwest winds. Weather models are varied on snowfall amounts, 0-25 cm

MONDAY: Clearing trend. Freezing level at valley bottom, rising to 500 m over the day. No precipitation expected. 

Avalanche Summary

There is evidence that an avalanche cycle occurred in the north of the region during the storm. Avalanches ranged from size 1 to size 2.5, with the majority starting around treeline.

If you are getting out in the mountains, we strongly encourage people to share observations on the Mountain Information Network.

Snowpack Summary

Storm slabs from the recent snowfall are settling, but remain sensitive to human triggers. 

The new snow and total snowpack are significantly deeper in the Pine Pass area than the rest of the region. Strong southwesterly winds and warm temperatures have made conditions quite variable depending on elevation and wind exposure.

Recent observations suggest treeline snow depths are around 80-140 cm with very little snow below 1400 m in much of the region except for the Pine Pass area which now has enough snow below treeline to avalanche.

A series of storms over the past few weeks delivered about 40-80 cm of snow, which sits above an early season crust(s). Reports indicate the snow has generally bonded well to the early season crusts. Exceptions may be shallow alpine slopes along the eastern side of the Rockies towards Jasper.

Terrain and Travel

  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Avoid freshly wind loaded terrain features.
  • Remember that the snowpack will be significantly different at higher elevations than lower down.
  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.