Avalanche Forecast

Issued: Mar 14th, 2017 3:56PM

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

mgrist, Avalanche Canada

Cariboos.

Warming is driving the avalanche danger higher: Don't underestimate the effect of high freezing levels or sunny afternoons. Conservative terrain use is essential this week and watch out for overhead hazard.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Warm temperatures and high freezing levels continue with moderate winds and precipitation in the south of the region on Wednesday. WEDNESDAY: Another 10-20cm of fresh snow is possible in the very south of the region, accompanied by moderate south winds. Freezing levels near 1700m. THURSDAY: Sunny breaks with flurries (up to 5cm) accompanied by moderate southwest winds. Freezing levels dropping to 1200m. FRIDAY: Cloudy with isolated flurries (5cm) with moderate southwest winds. Freezing levels near 1200m.

Avalanche Summary

A widespread natural avalanche cycle to Size 2.5 was reported below treeline on Monday afternoon as temperatures warmed up.Wet slabs to Size 2 were also reported on east aspects below treeeline. On Saturday skiers in the north of the region were able to trigger a Size 1.5 storm slab, sliding on a wind-pressed layer below. See here for their MIN report.

Snowpack Summary

Warming temperatures on Monday afternoon destabilized the snowpack, resulting in a widespread natural avalanche cycle below treeline. Use extra caution for the time being in what is normally a 'safer' elevation band. Surface snow up to 2000m is moist (read: heavy). We've had 5-15cm of fresh snow (with moderate to strong southerly winds) each of the past several days. 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 reactive wind slabs at treeline and above. All this recent snow is bonding slowly 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 may find the mid-February persistent weakness. Professionals in the region have also warned that a 'threshold load' has been reached above this interface, particularly where it presents as a crust.Deep persistent weaknesses (over 1.5 metres down) still have the potential to react to human triggers or smaller slab avalanches, especially with the warming temperatures or solar inputs.

Problems

Storm Slabs

Weaknesses within and below 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.

Minimize overhead exposure during periods of heavy loading from new snow, wind.If triggered, the storm slabs may step down to deeper layers resulting in large avalanches.

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 15th, 2017 2:00PM