Avalanche Forecast

Issued: Apr 28th, 2023 4:00PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is high. Known problems include Deep Persistent Slabs, Cornices and Loose Wet.

Avalanche Canada mconlan, Avalanche Canada

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A high freezing level will destabilize the snowpack, potentially triggering numerous different avalanche problems. Check out the latest Forecasters' Blog for more information.

Summary

Confidence

Moderate

Avalanche Summary

Riders should expect wet loose or slab avalanches and cornice failures during periods of warm air, with associated sunny skies or rain. Avoiding steep slopes when the snow feels sloppy and avoiding cornice exposure are good travel habits.

The likelihood of triggering very large avalanches releasing on the buried weak layers described in the Snowpack Summary will increase with each day of warming with this spring weather. This is particularly true for days without an overnight surface refreeze. Humans are most likely to trigger these layer in steep and rocky slopes where the snowpack is relatively thin.

Snowpack Summary

A moist snow surface is expected with a high freezing level, which may or may not freeze into a melt-freeze crust overnight.

Various layers of surface hoar, facets, and crusts may be found around 50 to 150 cm deep in coastal areas and 30 to 50 cm in shallower snowpack areas in the north and east of the region.

Weak faceted grains may exist near the base of the snowpack, particularly in shallower snowpack areas.

Cornices are large and looming at this time of year and will weaken with daytime warming.

Weather Summary

The freezing level will peak at 3300 m Friday night before slowly declining to 2500 m for Saturday with associated sunny skies. Sunday will see light rain or high alpine snow with a freezing level around 2200 m. A mix of sun and cloud with a rising freezing level to 2500 m is expected for Monday.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.
  • The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • Cornice failures could trigger very large and destructive avalanches.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Weak layers may be found in the middle and near the base of the snowpack, which are likely to reawaken with the variety of weather we receive during the spring. Small avalanches and cornice falls have the potential to trigger these deeper layers. Human triggered avalanches are most likely in steep, shallow, and rocky terrain where the snowpack is relatively thin.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2.5 - 4

Cornices

An icon showing Cornices

Cornices are large at this time of year and will become more prone to fail as they warm up with spring weather. Stay well back from them when on ridgelines and limit your exposure when travelling on slopes below them, as their release is unpredictable. Cornice falls could trigger very large slab avalanches on slopes below them.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Loose Wet

An icon showing Loose Wet

Wet loose avalanche activity is expected with daytime warming and during periods of strong sun. This problem can quickly change over the day. Stable conditions in the morning can turn very unstable during the heat of the day. Limit your exposure to steep terrain when the snow feels sloppy.

Wet slabs are also possible within the recent storm snow, particularly where it overlies a hard melt-freeze crust.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Valid until: Apr 29th, 2023 4:00PM