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Avalanche Forecast

Archived

Jan 30th, 2022–Jan 31st, 2022

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

Regions

South Rockies.

New wind slabs are expected to be touchy on Monday, especially where they overlies surface hoar or a crust. Loose dry avalanches should be expected on steep slopes. 

Confidence

Low - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

A storm system brings snowfall to the region Sunday night and is expected to linger through part of the day on Monday. Modelled snowfall amounts and timing are highly variable which is creating a lot of uncertainty for conditions on Monday. 

Sunday Night: Snowfall 10-15 cm, moderate to strong SW wind, treeline temperature -5 C°.

Monday: Snowfall 5-10 cm, moderate SW wind, treeline high around -6 C°.

Tuesday: Unsettled with snow flurries and sunny breaks both possible, light variable wind, treeline high around -12 C°.

Wednesday: Mainly sunny, light variable wind, treeline high around -15 C°.

Avalanche Summary

No recent avalanches have been reported in the last few days.

The last report of deep persistent slab avalanches is from January 21, when some very large avalanches were triggered by cornice falls and wind slab avalanches. Although deep persistent slab activity has recently tapered, it could still be possible to trigger large avalanches in steep, rocky terrain.

Snowpack Summary

The new snow will bury heavily wind affected snow surfaces in exposed terrain, a melt-freeze crust at low elevations and on solar aspects extending into the alpine, and surface hoar in sheltered terrain. The January 18 melt-freeze crust extends up to around 2000 m elevation and can be found down around 20 cm.  

The primary persistent layer of concern in the snowpack is a crust that formed in early December and is now 100-200 cm deep. This layer is found most areas through the region, but with varying test results. Recently, the layer has shown more reactivity in shallow snowpack areas.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
  • Conditions may have improved, but be mindful that deep instabilities are still present.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.