Dangerous avalanche conditions exist as the snowpack experiences very high freezing levels. Read more in the Forecasters' Blog.

Summary

Confidence

Moderate

Avalanche Summary

An avalanche cycle of large to very large (size 2 to 4) wet loose and slab avalanches, cornice failures, and deep persistent slab avalanches continues over much of the region. We expect this cycle will continue over the coming days.

Snowpack Summary

A moist snow surface is expected.

The intense addition of heat to the snowpack is reawakening dormant weak layers, including weak snow above crusts buried in late March (50 to 100 cm deep) and the weak basal facets found at the bottom of the snowpack. The timing of when and where persistent slabs will reawaken is uncertain, but will increase with each day of warming.

The snowpack is diminishing below treeline, but persistent and deep persistent slab avalanches could release at higher elevations and run into valley bottoms.

Weather Summary

A ridge of high pressure is in place, bringing a mix of sun and cloud with freezing levels near 3400 m for Friday. No overnight refreeze is expected. The ridge is expected to break down on the weekend, with a freezing level decline and incoming precipitation.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Avoid steep slopes when air temperatures are warm, or solar radiation is strong.
  • Minimize exposure to overhead avalanche terrain, large avalanches may reach the end of runout zones.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
  • The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Expect very large avalanches to release on buried weak layers as intense warming destabilizes the snowpack. Layers of concern include weak snow above hard crusts buried about 50 to 100 cm deep and weak facets near the bottom of the snowpack.

Human triggered avalanches are most likely in steep, shallow, and rocky terrain, where the snowpack is relatively thin.

Naturally triggered avalanches could occur without warning and are most likely on days when there isn't a good overnight refreeze. Resulting avalanches could travel far and even into snow-free valleys. For this reason, recognizing and avoiding areas with large overhead avalanche slopes, even if they are out of sight, is very important.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2.5 - 4

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, with activity ramping up as the sun starts shining on steep slopes.

Wet slabs are also possible, particularly on sun-exposed slopes where a buried melt-freeze crust exists in the upper snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1.5 - 2.5

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, North West.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Valid until: May 5th, 2023 4:00PM

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