Avalanche Forecast

Archived

Dec 16th, 2025–Dec 17th, 2025

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

South Coast Inland, Birkenhead, Duffey, South Chilcotin, Stein, Taseko.

Be ready to manage new storm / wind slabs, but don't let them overshadow the destructive persistent slab lurking below. Let the high consequence of triggering one guide your terrain choices.

Confidence

Moderate

Forecast snowfall amounts are uncertain.
Uncertainty is due to rapidly fluctuating freezing levels.

Avalanche Summary

Observations from the Duffey on Monday included five natural releases in the size 2.5 to 3 range, in addition to explosives results. As suspected with the size 3's in the Hurley and Upper Lillooet on Sunday, all are reported to have failed on the mid-November crust.

Looking forward, moderate snowfall and warming Tuesday night should promote similar activity. Although a shift toward new snow problems is expected, it's certainly not time to dismiss the persistent problem.

Snowpack Summary

10 - 25 cm of new snow should accumulate at higher elevations by Wednesday morning (expect rain below about 1500 m), covering a rain-soaked snowpack to about 2100 m and adding to somewhat uncertain dry snow accumulations above this elevation.

A crust with facets, formed in mid-November, was buried 50 to 100 cm before the storm. Recent very large wet slab and persistent slab releases failed on this layer and continuing loading prevents us from gaining confidence in it, even as temperatures cool.

Weather Summary

Tuesday Night
Cloudy with continuing precipitation bringing 10 to 25 cm of new snow above 1700 m, rain as high as 1500 m. 30 km/h southwest ridgetop wind. Treeline temperature reaching 0 °C with a period of 1700 m freezing levels.

Wednesday
Mostly cloudy with isolated flurries. 30 km/h southwest ridgetop wind. Treeline temperature -5 °C. Freezing level 1100 m.

Thursday
Mostly cloudy with continuing flurries bringing 10 to 20 cm of new snow, including overnight amounts. 15 to 30 km/h south ridgetop wind, easing. Treeline temperature -3 °C. Freezing level to 1400 m.

Friday
Mix of sun and clouds wit up to 5 cm of new snow from overnight. 10 km/h southwest ridgetop wind, easing. Treeline temperature -6 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Make observations and continually assess conditions as you travel.
Be especially cautious as you transition into wind-affected terrain.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.