Avalanche Forecast

Archived

Feb 22nd, 2014–Feb 23rd, 2014

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

Glacier.

http://www.pc.gc.ca/apps/scond/Cond_E.asp?oID=15974&oPark=100205Enjoy the great skiing in the park today by making very conservative terrain choices and using good group management.

Weather Forecast

A cold, dry air mass moves into the region today staying in place for the forecast period. Expect a mainly cloudy day with alpine temperatures around -11 and light ridge top winds. Sunny skies with alpine temperatures below -15 are forecast for Sunday and Monday.

Snowpack Summary

1-1.4m of storm snow is settling into a cohesive slab over the Jan 28/22 facet/surface hoar/crust interface. Snowpack tests suggests this weak layer is difficult to trigger, but if failed has high propagation propensity. In addition, layers in the top 60cm of the storm slab are reactive and if triggered will likely step down to the Jan 28/22.

Avalanche Summary

Yesterday a few natural avalanches were observed along the highway corridor size 1.5 to 2. Close neighbours are reporting large skier triggered avalanches up to size 3. Less obvious signs of instability cracking, recent avalanches activity and whumphing are being observed while traveling but the buried weak layers remain reactive.

Confidence

Due to the number of field observations

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.

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.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.