Avalanche forecast

South Rockies

Mar 11 – 12, 2012Avalanche Canada
View on map
Archived · expired 15 years ago

Avalanche danger

Tue
Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
Open full map

Highlights

Conditions are tricky. There is real potential to trigger surprisingly large avalanches. Traveling in avalanche terrain right now requires an advanced skill-set.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–6
    Wind slabs can be found behind ridges and terrain breaks.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–7
    A persistent weak layer around 1m deep has the potential to produce large and dangerous avalanches. It could be triggered by the weight of a person, remotely or in surprisingly mellow terrain. It is tricky to manage this problem, so be conservative.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–6
    Storm slabs may be found in any steep terrain. Storm slabs could step down to a persistent weak layer, creating destructive avalanches.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Monday: Cloudy with flurries turning to snow late in the day. Mild temperatures continuing, with the freezing level around 1500m. 8-15cm overnight. Strong south-westerly winds.Tuesday: Continuing snow and moderate south-westerly winds. A little bit cooler.Wednesday: Mainly cloudy with light flurries and possible sunny breaks. Light winds.

Avalanche Summary

A widespread natural avalanche cycle occurred up to size 3 in response to very warm temperatures and loading of start zones by strong winds on Friday and Saturday. Video footage here: https://bit.ly/yR4E8r . On Saturday, a snowmobiler was killed in a size 3 slab on a south-west aspect at treeline in the Corbin Creek area. Over the last week, there were several reports from in or near the region of near misses, including a snowmobiler who triggered an avalanche and was buried for around 30 minutes, remote-triggered avalanches, and slab avalanches running into unusually low-angled terrain.

Snowpack Summary

Recent storm snow has become moist on solar aspects, and on all aspects at low elevations. The mid February surface hoar layer is now down between 40 & 100cm and is more prevalent in the west and south of the region, particularly in the Flathead. Recent snowpack tests as well as a rider-triggered avalanche on this weak layer indicate that it still has the potential to be triggered in many areas and if it is triggered, a large avalanche could result. Remote-triggering, triggering from below and triggering on low-angled terrain are also concerns. Lingering concern remains for basal facets, particularly in shallower snowpack areas with steep, rocky start zones. Cornices have grown large and threaten slopes below.

Regions covered