Avalanche Forecast

Issued: May 1st, 2021 2:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is below threshold. Known problems include Wind Slabs, Cornices and Loose Wet.

Avalanche Canada mconlan, Avalanche Canada

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Avalanche conditions likely vary with elevation. Wind slabs may linger in the alpine and loose wet activity is possible at lower elevations.

Summary

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

SATURDAY NIGHT: alpine -4C, wind south 10 km/hr, mostly cloudy, trace precipitation

SUNDAY: alpine low -5C high -2C, wind south 15 km/h, mix of sun and cloud, trace precipitation

MONDAY: alpine low -3C high -1C, wind southeast 15 km/h, mostly cloudy, light precipitation, 1 to 3 cm accumulation

TUESDAY: alpine low -3C high -1C, wind south 30 km/h, mostly cloudy, light precipition, 2 to 5 cm accumulation

Avalanche Summary

Large (size 2) wet loose avalanches have been observed throughout the region, particularly during periods of rain or with warm air temperature.

Snowpack Summary

Above 1400 m, around 20 cm of dry snow may be found, which overlies a hard melt-freeze crust or other hard surfaces. Below 1400 m, the upper snowpack is wet from recent rain and warm air. The snowpack is isothermal near highway elevations, meaning it is generally unsupportive to human traffic.

The lower snowpack in White Pass is deep for this time of year with no layers of concern. Areas further inland, such as the Wheaton Valley, may have a shallower and weaker snowpack.

Cornices are still very large. Recent cold temperatures have kept cornice failures to a minimum but they should always be treated with respect in the spring, especially when the air temperature rises.

Terrain and Travel

  • Carefully evaluate steep lines for wind slabs.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
  • Avoid terrain traps where the consequence of any avalanche could be serious.

Problems

Wind Slabs

An icon showing Wind Slabs

20 cm or more of dry snow may be found above around 1400 m. Recent strong southwest wind may have blown this snow into wind slabs in lee terrain features. Assess for slab properties before committing to steep wind-loaded alpine terrain.

Aspects: North, North East, East, South East, North West.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Cornices

An icon showing Cornices

Cornices are large at this time of season. Best practice is to stay well-back from them on ridgelines and limit your exposure travelling beneath them.

Aspects: North, North East, East, North West.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Loose Wet

An icon showing Loose Wet

Assess for the wetness of the snow surface as you travel, particularly as you transition from treeline to alpine elevations. Use caution in very steep terrain if the snow surface is wet, and limit your overhead exposure of steep slopes.

Aspects: All aspects.

Elevations: Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: May 3rd, 2021 4:00PM