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Avalanche Forecast

Archived

Mar 21st, 2023–Mar 22nd, 2023

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Below Threshold.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Below Threshold.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely.
Below Treeline
Below Threshold.

Regions

Yukon, Tutshi, Wheaton, White Pass East, White Pass West.

Watch for new snow and southwest winds building fresh thin wind slabs that may be reactive to skier traffic in north and east facing terrain through the day.

Confidence

Moderate

Avalanche Summary

No new avalanches were reported in the region on Monday. Backcountry users may see evidence of a large avalanche cycle from the weekend as they travel through the terrain. These avalanches may have occurred during last week's storm or due to solar input and elevated freezing levels through the weekend.

On Sunday, a suspected skier triggered avalanche was reported. This was a size 1 storm slab avalanche that likely occurred on Saturday.

If you head out in the backcountry, let us know what you are seeing by submitting a report to the Mountain Information Network.

Snowpack Summary

Warm temperatures and strong winds have redistributed 50 cm of storm snow creating hard wind affected surfaces in alpine and exposed treeline terrain. This overlies previously wind affected snow (sastrugi) in exposed areas and faceted snow in sheltered features.

A buried weak layer of surface hoar can be found about 80 cm deep in Powder Valley, Tutshi, and Paddy Peak areas, 150 to 200 cm around White Pass. This layer is most prominent on northerly slopes sheltered from the wind. On other aspects, this layer is a hard melt-freeze crust with weak facets around it. This layer has been most problematic in alpine terrain.

The remainder of the middle of the snowpack is consolidated and strong. Weak faceted grains are found near the base of the snowpack, particularly in thin snowpack areas.

Weather Summary

Tuesday Night

Mainly cloudy with scattered flurries, 3-10 cm accumulation. Strong southwest ridgetop winds. Alpine temperature low -8°C. Freezing levels valley bottom.

Wednesday

Mainly cloudy with isolated flurries, 2 cm accumulations. Strong south ridgetop winds. Alpine temperature high -6°C. Freezing levels 500 m.

Thursday

Partly cloudy with isolated flurries, 2 cm accumulations. Moderate southeast ridge winds. Alpine temperature high -5°C. Freezing levels 700 m.

Friday

Mainly cloudy with isolated flurries, trace cm accumulations. Light south ridge winds. Alpine temperature high -7°C. Freezing levels 600 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.