Avalanche Canada dsaly, Avalanche Canada

South Rockies Avalanche Forecast

Mar 27th, 2020 5:00PM

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.

Steady winds continue to redistribute loose snow, the trend will continue as flurries accumulate through the weekend.

Summary

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

Friday night: Cloudy with isolated flurries, trace to 5 cm. Alpine low temperature -7 C. Moderate west wind. Freezing level 1500 m.

Saturday: Cloudy with scattered flurries, trace to 5 cm. Alpine high temperature -2 C. Moderate southwest wind. Freezing level 1700 m.

Sunday: Cloudy with scattered flurries, trace to 5 cm. Alpine high temperature -1 C. Moderate gusting to strong southwest wind. Freezing level 1800 m.

Monday: Flurries, 5-15 cm. Alpine high temperature -3 C. Moderate gusty southwest wind. Freezing level 1700 m and dropping.

Avalanche Summary

We have very limited field observations at this time. There have be no new avalanches reported in the region.

Snowpack Summary

15-25 cm recent snow is now wind affected and redistributed at treeline and above. A sun crust has formed on steep solar slopes and below treeline. Steady winds continue to impact loose surface snow. 

The recent new snow sits above a melt-freeze crust on sun-exposed slopes and on previously wind-affected snow in other areas, so new slabs may take some time to bond to these surfaces. A layer of faceted grains overly a melt-freeze crust from early February. This layer currently sits 40 to 80 cm below the surface. 

The base of the snowpack contains basal facets that are most prominent in shallow, rocky start zones.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Possible-Likely

Expected Size

1 - 2

Steady southwest winds are redistributing new flurries and loose surface snow building new wind slabs on leeward slopes, particularly near ridgetops and crossloaded terrain features.

Aspects:

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

Elevations:

Alpine, Treeline.

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Likelihood

Unlikely-Possible

Expected Size

2.5 - 3.5

Weak snow at the bottom of the snowpack hasn't gone away. Evidence of deep persistent slab avalanches has been focused in the Sparwood-Elkford area over the past month. Human triggering is most likely around steep, rocky terrain features or anywhere the snowpack is thin and weak. A failing cornice could initiate a deep persistent slab when it impacts the slope below.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Mar 28th, 2020 5:00PM