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Archived

Avalanche Forecast

Dec 18th, 2019–Dec 19th, 2019
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Banff Yoho Kootenay.

Recent SW winds have stripped the alpine, and loaded lee features with wind slabs.  Good skiing can be found in sheltered areas. 

Weather Forecast

Thursday - expect light flurries, moderate SW wind, and mild temperatures in the -5 to -10 range

Friday - the next storm begins elevating the avalanche hazard as it brings warmer temps (freezing levels at 1600 m), strong SW wind, and snow (15-30 cm depending on the weather model)

Saturday -  expect another 10-15 cm

Snowpack Summary

Strong winds have formed new wind slabs at alpine and tree line. The distribution of this new load is uncertain. Beneath the recent 40-60 cm of storm snow, the snowpack structure is generally weak, consisting of facets and depth hoar. The Nov crust is present up to 2500m and ~30 cm up from ground. Snowpack depths at treeline range from 80-160 cm.

Avalanche Summary

On Tuesday there was a Skier involvement in a size 2 windslab avalanche triggered on a convex roll at treeline (Paget Peak) and a natural size 2 windslab on a S alpine aspect of Noseum Peak.  Local ski hills continue to report small wind slabs reactive to ski cuts, although slightly less reactive compared to Tuesday

Confidence

Intensity of incoming weather systems is uncertain on Friday

Avalanche Problems

Wind Slabs

48 hrs of moderate to strong  winds have formed new wind slabs at alpine and tree line elevations. The distribution of the new load is uncertain. Where it is present you can expect the new load to be reactive in the short term.

  • Use caution in lee areas. Recent wind loading has created slabs over weaker snow.
  • Caution on open steep slopes at treeline that have been exposed to wind loading.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Deep Persistent Slabs

The recent snow sits over weak facet and crust layers. As time goes on the chance of triggering is becoming less likely, but there is lots of uncertainty as to where you could trigger an avalanche and what it will take to get it moving.

  • Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3