Avalanche forecast

Sea To Sky

Apr 2 – 3, 2022Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

Heavy snowfall and strong winds are expected to quickly raise the danger to HIGH on Sunday. 

A solar-triggered avalanche cycle is also possible on Sunday afternoon if the sky clears and the sun is strong.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2.5

    Large cornices will continue to grow during the storm and may become weak on Sunday afternoon if the sun is out for extended periods. 

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–2.5

    Storm slabs are expected to become touchy and widespread as the storm progresses, especially in wind-loaded terrain. A natural avalanche cycle should be expected in areas which receive the most snowfall.  

    Solar-triggered storm slabs are also possible on sun-exposed slopes if the sun makes an appearance on Sunday afternoon.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Rain at lower elevations will destabilize the upper snowpack. Loose wet avalanches are most likely at elevations where rain soaks new snowfall overlying a hard melt-freeze crust. 

    If the sun makes an appearance Sunday afternoon, solar-triggered wet loose avalanches should be expected on sun-exposed slopes. 

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system. Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

Stormy conditions are expected between Saturday night and Monday night expect for a brief period late Sunday afternoon when a break between systems is expected. Snowfall amounts are uncertain with weather models showing substantial variability. 

Saturday Night: Snowfall 10-25 cm, strong SW wind, freezing level low around 1000 m. 

Sunday: Snowfall 20-35 cm, sunny breaks in the late-afternoon, strong SW wind easing in the afternoon, freezing level high around 1300 m. 

Sunday night and Monday: Snowfall 40-60 cm, strong to extreme SW wind, freezing level high around 1200 m. 

Tuesday: A mix of sun and cloud, moderate W wind easing in the afternoon, freezing level high around 1200 m.

Avalanche Summary

Early reports from Saturday include an explosive-controlled size 2 cornice which triggered a size 1 storm slab on the slope below. 

On Friday, explosives triggered a couple size 1-2 cornices. One of these cornices triggered a slab avalanche on a northwest aspect in the alpine which likely failed on the mid-March interface down 50 cm.

Snowpack Summary

The new storm snow will continue to bury a strong, supportive crust which extends to mountain top on solar aspects and to around 2200 m on northerly aspects. Strong southwest wind will be redistributing the new storm snow in exposed high elevation terrain forming touchy wind slabs.

Below the crust, the upper snowpack consists of a number of crust/facet/surface hoar interfaces buried in March that seem to have bonded well during the recent warm weather. 

The middle and lower snowpack are generally strong and well bonded. 

Terrain and Travel

  • Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
  • Even brief periods of direct sun could produce natural avalanches.
  • The more the snow feels like a slurpy, the more likely loose wet avalanches will become.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Regions covered