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Avalanche Forecast

Archived

Feb 25th, 2023–Feb 26th, 2023

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

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, South Okanagan, Ymir, Moyie.

Head out with a storm day mindset - new snow will be increasingly reactive to human triggers.

Step back into conservative terrain as snow accumulates, it likely won't bond well with the wind affected surface below.

Confidence

Moderate

Avalanche Summary

This week, slab avalanches were produced to size 2 from natural triggers and accidental rider triggers, and to size 3 from explosive control methods. Activity occurred on all aspects from variable wind loading. Most avalanches occurred within the storm snow or wind loaded features, while a few failed on the buried surface hoar layer.

We expect a natural cycle as storm snow accumulates Saturday night and Sunday.

Snowpack Summary

By Sunday morning around 20 cm of low density storm snow is likely, overlying heavily wind affected surfaces at all elevations (Check out this MIN for wind effect photos). Expect deeper deposits in on north and east facing slopes, from southwest winds.

A layer of surface hoar can be found on shaded slopes, and a sun crust on sun affected slopes buried 30-60 cm deep. Otherwise, the snowpack is generally well consolidated and bonding.

The lower snowpack includes a layer of weak sugary crystals near the ground. These facets are slowly gaining strength and have not produced recent avalanche activity. We continue to track the layer and watch for any signs that it could wake up and produce very large avalanches.

Weather Summary

Saturday Night

Up to 25 cm of snow is expected with moderate southwest winds. Snowfall favors the north of the region, with 10-15 cm expected toward the border. Freezing levels remain below valley bottom.

Sunday

Snow continues with another 10 cm possible. Freezing levels around 600 m. Alpine high of -7 °C with moderate southwest winds.

Monday

Cloudy with sunny breaks possible. Moderate southerly winds ease to light. Freezing levels below valley bottom, alpine high of -5 °C. Possible flurries.

Tuesday

Mostly cloudy with flurries. Light southwest winds. Freezing levels below valley bottom, alpine high of -5 °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.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.

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.