Avalanche Canada cgarritty, Avalanche Canada

South Rockies Avalanche Forecast

Jan 9th, 2020 4:00PM

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

Our recent snow is on a positive stabilizing trend, but forecast strong winds will maintain elevated danger on Friday. Seek out sheltered low density snow for the best quality and safest skiing and riding.

Summary

Confidence

High -

Weather Forecast

Thursday night: Clear periods. Light northwest winds, increasing.

Friday: Increasing cloud with isolated flurries and a trace of new snow, continuing overnight. Moderate to strong southwest winds. Alpine high temperatures around -11.

Saturday: A mix of sun and cloud with cloud increasing and light flurries beginning overnight. Light southwest winds. Alpine high temperatures around -8.

Sunday: Mainly cloudy with isolated flurries and a trace to 5 cm of new snow, increasing overnight. Light to moderate south winds. Alpine temperatures cooling to around -15.

Avalanche Summary

Reports from the Castle area on Tuesday and Wednesday showed explosives control yielding storm slab and wind slab releases to size 2.5 (large). Most crown fracture depths were around 40 cm but some larger results were up to 80 cm deep.

Looking forward, the recent snow should begin to form a more reliable bond with the old surface as our slab problems become increasingly limited to wind-loaded areas.

Snowpack Summary

The recent storm brought about 25-40 cm of new snow to the region over the early part of this week. This snow has been redistributed by moderate to strong south and southwest winds in exposed areas at higher elevations.

The recent snow buried older wind slabs and other wind-affected surfaces in open areas at all elevations. This older, wind-affected snow forms the upper part of an increasingly consolidated mid-snowpack, which overlies our weak basal snowpack. 

The bottom 30-50 cm of the snowpack consists of weak facets and crusts. Although these layers have been unreactive in recent snowpack tests and have not produced avalanche activity recently, there is the potential for them to become reactive with large loads or significant warming.

Terrain and Travel

  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Keep your guard up at lower elevations. Wind slab formation has been extensive.
  • Avoid freshly wind loaded terrain features.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely

Expected Size

1 - 2

Recent winds have redistributed much of our new snow into reactive slabs at all elevations and on a wide range of aspects. Forecast southwest winds suggest north through east aspects will see the most aggressive slab formation on Friday. Keep avoiding thin or variable snowpack areas where a smaller wind slab could trigger a release on our weak basal snowpack.

Aspects:

All aspects.

Elevations:

All elevations.

Valid until: Jan 10th, 2020 5:00PM