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Avalanche Forecast

Archived

Apr 22nd, 2025–Apr 23rd, 2025

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

Haines Pass.

New slabs may form with snow and strong wind. It also remains possible to trigger large avalanches failing on buried weak layers in northerly alpine terrain.

Confidence

Moderate

Avalanche Summary

We've received a few reports of some recent large avalanches that likely released on buried weak layers (here and here). Most of the avalanches released on northerly alpine terrain.

Looking forward, new small avalanches may form from new snow that rests on surface hoar crystals. It will also remain possible to trigger large avalanches on northerly alpine terrain.

Please continue to share your observations via the Mountain Information Network. Thank you!

Snowpack Summary

5 to 10 cm of new snow will fall onto surface hoar crystals on shaded aspects and a melt-freeze crust at lower elevations and on sun-exposed slopes. Strong wind may form deeper deposits in lee terrain features.

We have limited snowpack information, but this report suggests a generally weak lower snowpack with various potential layers of concern, which produced recent large avalanches.

Weather Summary

Tuesday Night

Cloudy with 1 to 3 cm of snow. 30 km/h south ridgetop wind. Treeline temperature -3 °C.

Wednesday

Cloudy with 5 cm of snow. 40 km/h southeast ridgetop wind. Treeline temperature -1 °C. Freezing level 1000 m.

Thursday

Cloudy with 5 to 10 cm of snow. 20 to 40 km/h south ridgetop wind. Treeline temperature -1 °C. Freezing level 1000 m.

Friday

Mostly cloudy with 2 to 5 cm of snow. 20 km/h south ridgetop wind. Treeline temperature -1 °C. Freezing level 1000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for signs of slab formation throughout the day.
  • Make observations and continually assess conditions as you travel.
  • Be aware of the potential for large avalanches due to buried weak layers.
  • Cornice failures could trigger large and destructive avalanches.

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.