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Avalanche Forecast

Archived

Dec 20th, 2023–Dec 21st, 2023

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

North Rockies, Sugarbowl, Kakwa, McGregor, Pine Pass.

Fresh snow and increasing winds are further burying a concerning layer of surface hoar.

Confidence

Moderate

Avalanche Summary

No new avalanches have been reported. There are very few field observations coming from this forecast area. Remember that a lack of avalanche reports does not necessarily mean a lack of avalanche activity.

If you go out in the backcountry, please consider sharing your observations on the Mountain Information Network (MIN).

Snowpack Summary

New snow continues to bury a variety of previously wind-affected surfaces.

A problematic surface hoar layer is roughly 40 to 70 cm below the surface.

The mid snowpack likely contains multiple frozen crusts, while the lower snowpack is generally faceted. Average snowpack depths at treeline range from 50 to 100 cm.

Weather Summary

Wednesday Night

Mostly cloudy with 0 to 5 cm of snow, southwest alpine winds 50 to 60 km/h, treeline temperature -3 °C.

Thursday

Cloudy with 10 to 20 cm of snow, southwest alpine winds 50 to 70 km/h, treeline temperature -1 °C.

Friday

Cloudy with 5 to 15 cm of snow, southwest alpine winds 60 to 70 km/h, treeline temperature -4 °C.

Saturday

Mix of sun and cloud with no precipitation, southwest alpine winds 40 to 50 km/h, treeline temperature -8 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Choose conservative terrain and watch for clues of instability.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.

Problems

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.

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.