Avalanche forecast

South Rockies

Mar 8 – 9, 2015Avalanche Canada
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Avalanche danger

Tue
Wed
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Use increased caution on sun-exposed slopes during the afternoon heat. Deep weaknesses have the potential to wake-up with the strong warming.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–2
    Ongoing variable winds continue to build thin wind slabs in exposed leeward terrain features at higher elevations. Afternoon sun and warming may increase the sensitivity of triggering these wind slabs.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3–6
    Deeper weaknesses still exist and remain a concern in shallow rocky areas or anywhere the thick near-surface crust is weakening or non-existent, specially north aspects above 2200m.

Confidence

Fair - Due to the number of field observations

Weather Forecast

The ridge of high pressure will be the prominent feature for Monday and Tuesday before a weak coastal storm system pushes cloud into the region on Wednesday. On Monday, mainly sunny conditions are expected with freezing levels as high as 2300m. Alpine winds are expected to be moderate-to-strong from the W-NW. On Tuesday, a mix of sun and cloud is expected with freezing levels reaching around 2500m. Alpine winds are forecast to be moderate from the SW-W. On Wednesday, cloudy conditions are expected and light snowfall/rain is possible.

Avalanche Summary

On Sunday in Kananaskis Country, a skier-trigger slab released on a weak layer near the ground. On Saturday, wet sluffing was reported from steep sun exposed slopes in the Lizard range.  Similar activity is still possible on Monday as the heat and sun continues.  Human-triggering of old wind slabs also remains possible in isolated areas.

Snowpack Summary

Variable snow surface consists of wind-affected snow or wind-scoured crusts in exposed alpine areas, moist snow or sun crust on sun-exposed slopes, or 5-10cm of dry snow overlying an old crust in shady and sheltered areas. At higher elevations, ongoing winds may be continuing to build thin wind slabs in leeward features. Lower elevations are undergoing daily springtime melt-freeze cycles. The most prominent snowpack feature is a thick supportive crust 10-30cm below the surface. It extends up to around 2200m elevation. Below this elevation the crust is effectively capping the snowpack, preventing riders from stressing deeper persistent weak layers. In alpine areas where the crust is not present or is less thick, dormant persistent weak layers may still be lingering and could wake-up with heavy loading or strong warming.

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