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Avalanche Forecast

Archived

Nov 27th, 2019–Nov 28th, 2019

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

Purcells.

Clear and cold for the next few days. Snowpack depth is highly variable where there is enough snow to recreate.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

WEDNESDAY Night: Mostly cloudy with clear periods, light east wind, alpine temperature -18 C.

THURSDAY: Clear skies, light northeast wind, alpine temperature -16 C.

FRIDAY: Clear skies, light northeast wind, alpine temperature -14 C.

SATURDAY: Mix of sun and cloud, light east wind, alpine temperature -12 C.

Avalanche Summary

There have been reports of a skier and explosives triggering avalanches on north facing alpine terrain in the past few days.

If you see anything while out in the field, please consider sharing that information with us and fellow recreationists via the Mountain Information Network (MIN).

Snowpack Summary

Around 10 to 30 cm of recent snow may overly a weak layer of feathery surface hoar. The distribution of the surface hoar is currently not well understood. The recent snow has been blown around by moderate to strong northeast wind.

Snowpack depth is highly variable, ranging from 10 cm to 100 cm. Expect to find weak and faceted snow in the thin areas. Elsewhere, you may find a melt-freeze crust from late October above faceted snow near the base of the snowpack.

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.

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.