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Avalanche Forecast

Archived

Jan 6th, 2025–Jan 7th, 2025

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

Regions

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

Overnight snowfall and strong wind are increasing the avalanche hazard, especially in White Pass

Conservative terrain choices and avoiding overhead hazard is strongly recommended.

Confidence

Moderate

Avalanche Summary

The most recent avalanche reports are from last Wednesday, this MIN reported whumping and shooting cracks.

Last Tuesday, a large (size 2) avalanche failed on the persistent weak layer. Click on the photo below for details.

We expect the likelihood of both natural and human-triggered avalanches to increase in White Pass during this stormy period.

Snowpack Summary

5 to 25 cm of new snow accompanied by extreme southerly winds is expected to form fresh storm slabs overnight Monday. Due to the forecast winds, we expect the most reactive storm slabs will be on north-facing slopes. White Pass is expected to get the highest precipitation amounts, with drastically less snow falling further inland.

An additional concern is a persistent weak layer of a crust with overlying facets, and in some cases surface hoar. This interface is currently buried 20 to 30 cm deep and extends up to 1750 m.

Despite the presence of faceted grains in the lower snowpack, there are no current layers of concern below the crust. 

Snowpack depths range from about 70 to 180 cm.

Weather Summary

Monday Night

Cloudy with 5 to 25 cm of new snow. White Pass is expected to get the highest amounts, with drastically less snow further inland. Extreme south ridgetop winds: 75 to 85 km/h. Treeline temperature 0 °C.

Tuesday

Cloudy with 0 to 5 cm of snow. Extreme southwest ridgetop winds: 70 to 90 km/h. Treeline temperature -2 °C.

Wednesday

Cloudy with 0 to 5 cm of snow. 50 to 60 km/h southwest ridgetop wind. Treeline temperature -3 °C.

Thursday

Cloudy with 5 to 15 cm of snow. 60 to 80 km/h south ridgetop wind. Treeline temperature -2 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Be careful as you transition into wind-affected terrain.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.