Avalanche forecast

Lizard-Flathead

Mar 18 – 19, 2019Avalanche Canada
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Archived · expired 8 years ago

Avalanche danger

Wed
Thu
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

This is a good time to avoid avalanche terrain.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1.5–3
    The weak layers present in our snowpack are undergoing a stress test that increases with each day of warm temperatures and weak overnight cooling. The deeply buried surface hoar layer from mid January is a primary concern at lower elevations.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2.5
    Sunshine and warm temperatures will peel away layers or recent snow on sunny slopes as loose wet slides, weaken cornices, and possibly re-energize wind slabs. Expect loose wet avalanche activity to expand to shaded aspects under sustained warming.

Confidence

High -

Weather Forecast

Monday night: Clear. Light northeast winds. Freezing levels rising to 2800 metres.Tuesday: Sunny. Light variable winds. Alpine high temperatures around +7 with freezing levels rising to 3100 metres and remaining elevated overnight.Wednesday: Sunny. Light southeast winds. Alpine high temperatures around +9 with freezing levels around 3200 metres, dropping slightly overnight.Thursday: Sunny. Light southwest winds. Aline high temperatures around +7 with freezing levels around 3000 metres, dropping slightly overnight.

Avalanche Summary

Reports from Sunday showed a continuation of natural loose wet avalanche activity focused on sun exposed aspects, with some releases reaching size 2.5 as they gouged into the snowpack to entrain more mass.Saturday's reports are of significant warming but only small loose wet avalanches. Neighbouring regions (for example Kananaskis Country) where the snowpack is thinner and weaker entered a natural avalanche cycle involving most aspects, most elevations, and most snowpack layers.On Thursday, a group of riders remotely triggered a size 1.5 persistent slab from 100 metres away. See the MIN report for more details. This is an important piece of data when considering the effect of forecast strong sunshine and warming on persistent slab problems that developed earlier in the season.Looking forward, the type of activity shown above can be expected to continue, expand to all aspects, and perhaps intensify as temperatures remain elevated and overnight cooling remains weak.

Snowpack Summary

Upper snowpack: Getting warm and moist during the day, maybe forming ephemeral crusts overnight. On sunny aspects there may be buried crusts serving as sliding layers. On lee slopes there may be buried hard layers of wind effected snow (buried wind slabs). There might even be some good old soft snow (powder hiding out on high elevation shadier places). Mid pack: The mid-snowpack consists of sugary faceted grains (facets) of different hardness. Two older layers of surface hoar still exist down 55-80 and down 95-150 around 1600-1900m. See Avalanche Activity section below for why this is relevant!Lower pack: Was reportedly strong in deep snowpack regions, but I have doubts in shallower areas where the long February cold weakened even the deep layers. Now add a bunch of heat and sun ... the snowpack won't be feelin' the love. Forecasting how many sunny days and warm nights it's going to take to wake up deeper layers is tough; however, I can say with confidence it's a good time to stand aside, watch from afar, let the mountains shed their coat, and come back to the game when things return to normal after the temperatures cool.

Regions covered