Avalanche Forecast

Issued: Apr 3rd, 2017 3:36PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs, Persistent Slabs and Loose Wet.

triley, Avalanche Canada

Cariboos.

Recent storm or wind slabs in the alpine may continue to be reactive to human triggers. Avoid slopes below cornices, sun and daytime warming may result in natural releases.

Summary

Confidence

- Timing or intensity of solar radiation is uncertain on Tuesday

Weather Forecast

Overnight: Light winds, mostly clear with freezing to valley bottoms. Tuesday: Mix of sun and cloud with moderate southwest winds and daytime freezing up 1500 metres. Wednesday: Overcast with light snow in the afternoon. Moderate southwest winds and daytime freezing up to 1800 metres. Thursday: 5-10 cm of new snow above 1200 metres by morning. Light winds during the day with daytime freezing up to 1600 metres.

Avalanche Summary

No new avalanches reported. Spring melt-freeze cycle ongoing, expect moist snow at lower elevations and on solar aspects in the afternoon.

Snowpack Summary

Last week's stormy weather brought up to 40 cm of snow to upper elevations. This storm snow overlies a rain crust below about 2000 metres and a sun crust on solar aspects at higher elevations. Several other temperature and or solar crusts are likely to exist within the storm snow, mainly at lower elevations and on solar aspects. Moderate to strong southwest winds during and since the snowfall formed wind slabs on leeward slopes and promoted the growth of large, fragile cornices along ridgelines. At higher elevations, the February weak layers are down about 120-150 cm and the deep mid-December facet layer and November rain crust both still linger near the bottom of the snowpack. These layers were active during a storm in mid-March and produced some very large avalanches. Occasional deep releases were also reported in late March and these deeply buried weaknesses remain a serious concern as solar radiation and warming temperatures begin to penetrate the snowpack at increasingly higher elevations. Cornices and wind slabs are also weakened by these warming effects and have the potential to trigger deeply buried weak layers if they release.

Problems

Wind Slabs

Recent southwest winds have redistributed storm snow in exposed terrain at higher elevations, forming large wind slabs. These slabs weaken and become increasingly reactive with daytime warming.

Use ridges or ribs to avoid pockets of wind loaded snow.Look for patterns of wind loading and avoid traveling near thinner edges of wind slabs.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

A cornice fall or smaller slab avalanche could trigger large, destructive avalanches on deeply buried weak layers. The likelihood of this happening will increase as solar warming weakens unstable cornices and wind slabs over the course of the day.

Recognize and avoid runout zones.If triggered, wind slabs or cornices may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 4

Loose Wet

Solar warming will progressively deteriorate the surface of the snowpack at lower elevations and on solar aspects. Snow that becomes moist will have the tendency to sluff from steep terrain, either naturally or with a human trigger.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Apr 4th, 2017 2:00PM