Avalanche Canada cgarritty, Avalanche Canada

South Rockies Avalanche Forecast

Jan 10th, 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.

Strong winds are maintaining elevated avalanche danger at all elevations. Tune in to local wind loading patterns and seek out sheltered low density snow for the best, safest skiing and riding.

Summary

Confidence

High -

Weather Forecast

Friday night: Cloudy with isolated flurries and a trace of new snow. Moderate to strong southwest winds, easing into the morning.

Saturday: Cloudy with isolated flurries and a trace of new snow, increasing a bit overnight. Light southwest winds. Alpine high temperatures around -8.

Sunday: Cloudy with continuing flurries bringing up to 5 cm of new snow, continuing overnight. Light to moderate south winds. Alpine temperatures cooling to around -20.

Monday: Mainly cloudy with isolated flurries and a trace of new snow. Light southwest winds, becoming moderate or strong at ridgetop.

Avalanche Summary

A few more large (size 2.5) wind slabs were controlled with explosives in the Castle area on Thursday. 

Another notable report came from a observers witnessing a skier trigger a small windslab that managed to step down to the basal snowpack to produce a very large (size 3) deep persistent slab. This occurred in a shallow, rocky gully in the Castle area. Its crown fracture was 30-100 cm deep.

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

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 a generally weak basal snowpack.

The bottom 10-20 cm of the snowpack consists of facets and deteriorating crusts. This basal layer has gradually been gaining strength, but potential still exists for large triggers in thin, rocky areas to trigger avalanches at this depth.

Terrain and Travel

  • Keep your guard up at lower elevations. Wind slab formation has been extensive.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Avoid freshly wind loaded terrain features.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible-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. Strong southwest winds promoted 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:

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

Elevations:

All elevations.

Valid until: Jan 11th, 2020 5:00PM