Avalanche Forecast

Issued: Nov 29th, 2022 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs and Wind Slabs.

Avalanche Canada GS, Avalanche Canada

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The cold temperatures will persist all week, with a refresh of new snow coming on Wednesday, but the snowpack is weak and human triggering is likely in many areas while natural avalanche activity has slowed. This is a classic start to the Rockies' winter season: a shallow, weak snowpack prone to human triggering that is slow to change. Settle in for a conservative start to your winter.

Summary

Confidence

Moderate

Avalanche Summary

Nothing was reported on Tuesday, but on Monday a size 2 skier triggered avalanche failed on the ground adjacent Lake Louise ski area, along with a surface hoar avalanche near Sunshine and two size 2-2+ Na avalanches on the 93N that appear to have failed on the basal facets.

Snowpack Summary

25-30 cm of storm snow has accumulated over the past 7 days at treeline that has now settled into a slab overlying a mix of weak facets, surface hoar, or sun crust on steep south aspects (ie: very weak base). 40-80 cm of total snow exists at treeline throughout the region, with up to 120 cm in loaded alpine features.

Weather Summary

An arctic ridge of high pressure remains anchored in Alberta while a low-pressure system moves across BC starting Tuesday night and through the day on Wed. This will produce 5-10 cm of snow in most of the region by Wed while temperatures remain cold (-20ish) and winds light from the south. No warm-up is expected for at least another week.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.

Problems

Persistent Slabs

An icon showing Persistent Slabs

Likelihood

Possible - Likely

Expected Size

1 - 2.5

Recent snow and wind loading has created slabs over a persistent weak layer of facets, buried sun crusts, or isolated pockets of surface hoar. This slab has been sensitive to natural and human triggering and can result in full depth avalanches.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 1.5

Another 5-10 cm of low-density snow on Wednesday will create small windslabs in leeward areas. If triggered, these slabs could step down to the deeper facet layers and result in a larger than expected avalanche.

Aspects:

North, North East, East, South East, North West.

Elevations:

Alpine, Treeline.

Valid until: Nov 30th, 2022 4:00PM

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