Avalanche Forecast

Issued: Nov 18th, 2019 4:00PM

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

Parks Canada aaron beardmore, Parks Canada

Email

Heavy loads (explosives) producing size 2 avalanches on the October crust. Keep on the look out for wind-slabs at your local level.

Summary

Weather Forecast

Light precip (7-10cm) followed by a cooling trend is expected Tuesday. Winds will also abate, however wind velocity will rise and fall from the moderate range to calm over the next few days. Clearing expected early Thursday.

Snowpack Summary

Yesterday, 5-10 cm of new snow with warm temps and strong SW winds was loaded in lee areas and built cornices. 10-25 cm of settled snow sits over the Nov 8 crust. Faceting observed near the ground and Oct crust, resulting in easy test results in some areas. Treeline snow depths range from 50-80 cm, with up to 110 cm in wind loaded alpine areas.

Avalanche Summary

Lake Louise ski area was reporting that explosive control was producing wind-slabs that would step down to the Oct crust producing numerous size 2 avalanches.

Confidence

Wind effect is extremely variable on Monday

Problems

Wind Slabs

An icon showing Wind Slabs

Small amounts of new snow and recent strong SW wind on Monday have created new wind-slabs in lee areas in the alpine. The wind was strong enough to move snow around at treeline but slab development was less prominent at this elevation band.

  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

The basal facets and Oct crust have been most reactive in the Lake Louise area, but it is likely that similar pockets exist throughout the forecast area. Keep watching for weak areas at the base of the snowpack, especially in steep or convex terrain.

  • Convex features and steep unsupported slopes will be most prone to triggering.
  • Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Nov 19th, 2019 4:00PM