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Avalanche Forecast

Archived

Mar 17th, 2023–Mar 18th, 2023

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

Regions

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

Lingering wind slabs may remain reactive to human triggers in isolated locations at upper elevations.

Avoid shallow, rocky areas or where the snowpack transitions from thin to thick.

Confidence

Moderate

Avalanche Summary

A couple cornice triggered wind slabs up to size 2.5 were reported on steep, northerly aspects in the alpine on Thursday.

Snowpack Summary

Southerly winds continue to redistribute the 15 to 25 cm of recent snow. Higher-elevation wind slabs may remain reactive. March sun and warm daytime temperatures may begin to have an effect on the snowpack. Crusts may form on steep solar slopes and at low elevations.

The new snow is sitting on generally hard surfaces from extensive wind effects or a thin sun crust on steep, sunny slopes.

The middle of the snowpack is generally well-settled and consolidated.

A weak layer of large and fragile facets is found near the base of the snowpack. This layer is of most significant concern in shallow snowpack areas in the north and east of the region.

Weather Summary

Friday Night

Partly cloudy / 20 km/h southwest ridgetop wind / Temperature at treeline around -8 C / Freezing level valley bottom

Saturday

Mix of sun and cloud / 10 km/h southwest ridgetop wind / Temperature at treeline around -2 C / Freezing level 1700 m

Sunday

Sunny / 20 km/h southeast ridgetop wind / Temperature at treeline around -1 C / Freezing level 1800 m

Monday

Mix of sun and cloud / 40 km/h southeast ridgetop wind / Temperature at treeline around -2 C / Freezing level 1700 m

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

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.