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Avalanche Forecast

Archived

Nov 22nd, 2013–Nov 23rd, 2013

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

Regions

Cariboos.

Forecasts are based on limited observations. You need to be the detective. Dig down, test weak layers and keep an eye on rising temperatures throughout the weekend.

Confidence

Poor - Due to the number of field observations

Weather Forecast

High pressure will dominate though the forecast period. This will bring warming temperatures, rising freezing levels and temperature inversions. Some forecasts suggest alpine temperatures could rise as high as 5 degrees celsius. Ridgetop winds will be light from the West and no significant precipitation is expected.

Avalanche Summary

During the storm earlier this week a widespread natural avalanche cycle in the alpine occurred. Size 2-3 slab avalanches were reported throughout the region. Recently, only smaller size 1-2 avalanches have been reported. However, isolated very large slab avalanches may occur naturally and could be rider triggered, especially in areas that didn't previously avalanche. Check out a rider triggered slab avalanche from the Valmount area earlier this week here. Thanks to Curtis Pawliuk from RideValmount.com for his insights.

Snowpack Summary

Recent storm snow seems to be settling, but wind slab problems do exist. A surface hoar layer exists  60-120 cm down but seems to be spotty, and drainage specific. A bigger concern is a melt-freeze / rain crust that formed early October. This is generally found from 80-180 cm down, and was reactive earlier this week. Sugary facetted crystals have a poor bond above and below the crust. The crust seems to be widespread through the region. Northerly aspects may have a more predominant crust that that might allow for wider propagations and bigger avalanches, especially places that have smooth ground cover (glacier ice, grassy slopes, rock slabs etc.).

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.