Avalanche Forecast

Issued: Mar 12th, 2017 4:50PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Persistent Slabs.

mgrist, Avalanche Canada

Cariboos.

Snow, wind and warming are a recipe for elevated danger. Storm and wind slabs will be touchy at treeline and above. Conservative terrain use is essential this week!

Summary

Confidence

Low - Intensity of incoming weather systems is uncertain

Weather Forecast

We'll have moderate snowfall amounts through to Monday morning, and then it starts to warm up Monday afternoon. MONDAY: Cloudy with another 10-15cm by morning accompanied by moderate to strong SW winds and freezing levels rising as high as 1500m. TUESDAY: Scattered flurries (3-5cm) with moderate southerly winds. Freezing levels remain near 1600m. WEDNESDAY: Cloudy with another 10-15cm of fresh snow throughout the day accompanied by moderate SW winds. Alpine temperatures hovering around -3 C.

Avalanche Summary

No new reported yesterday. Several Size 1 avalanches were reported Friday on steep solar (south) aspects.On Friday morning, skiers were able to trigger a Size 1.5 storm slab (with good propagation) in a cross loaded slope near a shallow rocky area. Aspect was north/northeast. See here for their great MIN report.

Snowpack Summary

We've had 5-15cm of fresh snow (with moderate southerly winds) each of the past three days, which adds to the 40-80cm of settled storm snow from the past week. Touchy storm slabs can be found at all elevations with weaknesses within and under this recent snow. Recent moderate to strong southerly winds have created touchy wind slabs at treeline and above. All this recent snow is bonding poorly to faceted snow, thin sun crust on steep southerly aspects, as well as surface hoar in sheltered areas in some parts of the region. About 80-120 cm below the surface you'll likely find the mid-February persistent weakness, which is composed of a thick rain crust up to about 1700 m, sun crusts on steep solar aspects, and spotty surface hoar on shaded aspects. Professionals in the region have also warned that a 'threshold load' has been reached above this interface, particularly where it presents as a crust.Some lingering surface hoar weaknesses from January are now down over a metre and the weak mid-December facets are down about 1.5 metres. These deep persistent weaknesses still have the potential to react to human triggers or smaller storm slab avalanches.

Problems

Storm Slabs

Weaknesses within the recent storm snow are susceptible to human triggering. These storm slabs are particularly deep and touchy on slopes loaded by southerly winds and have the potential to step down to deeper persistent weaknesses.

Be alert to conditions that change with elevation.If triggered, the storm slabs may step down to deeper layers resulting in large avalanches.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

Persistent weakness layered throughout the snowpack create the potential for very large step-down avalanches. The risk of triggering a deeper weak layer will be heightened while overlying storm slabs remain sensitive to human triggering.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.Avoid lingering in runout zones.Avoid or use extreme caution around thin snowpack areas.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Mar 13th, 2017 2:00PM