Avalanche forecast

South Coast

Mar 28 – 29, 2016Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Substantial warming and sun exposure on Tuesday will destabilize the upper snowpack. Extra caution is required around and below cornices, in recently wind loaded areas, and on steep sun exposed slopes.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Wind slabs should be expected in immediate leeward features on all aspects in exposed terrain.  Wind loading was from the south over the weekend but switched to north on Monday causing reverse loading.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Large cornices are expected to get weak with warming and sun exposure, and natural cornice releases are possible in the afternoon.  They can be destructive by themselves, and may also become the trigger for a slab avalanche on the slope below.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Loose wet sluffing is expected on sun exposed slopes during the heat of the afternoon.  Rising freezing levels may increase the size and run length of natural sluffing.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

A blocking ridge of high pressure is the dominant feature for the week.  Dry and clear conditions are expected for Tuesday through Thursday.  Freezing levels are expected to climb to around 2500m on Tuesday afternoon and should be around 3000m on both Wednesday and Thursday afternoon, with cooling during the overnight periods.  Moderate outflow winds are expected on Tuesday in exposed terrain.  Light to moderate outflow winds are forecast for Wednesday and light outflow winds for Thursday. 

Avalanche Summary

No new avalanches were reported on Sunday.  On Saturday, wind slab activity up to size 1.5 was reported as well as loose wet avalanches up to size 1.5. As things heat up on Tuesday, natural cornice releases and solar triggered sluffing are both expected. Cornices have the potential to trigger lingering storm slabs on the slopes below, especially on north aspects. Wet slabs may be possible on steep south facing terrain.

Snowpack Summary

10-20cm of new snow accumulated over the weekend in sheltered areas. Over the weekend, southerly winds were loading north aspect leeward slopes. However, outflow winds on Monday are reported to be loading south aspects in the alpine while exposed north aspect slopes are being wind pressed and scoured. Large cornices are lingering and are expected to become very weak this week. Below the surface problems, the mid snowpack is generally well-settled throughout with no notable persistent weaknesses. On Monday, a sun crust is expected to have formed on south aspects. Melt-freeze conditions are expected to be widespread this week with very high freezing levels.

Regions covered