Avalanche Forecast

Issued: Apr 6th, 2014 9:16AM

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

triley, Avalanche Canada

South Rockies.

Forecast warm temperatures, high freezing levels, and sunny skies are expected to increase the avalanche danger. Check out the new blog post here.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Overnight and Monday: Freezing levels remaining at 2000 metres overnight and then climbing to 2700 metres during the day. Light to moderate Westerly winds and clear skies with strong solar radiation. Tuesday: Freezing level remaining at 2700 metres overnight and through the day. Mostly sunny with developing clouds in the afternoon as Southwest winds build to strong values.Wednesday: Freezing levels dropping overnight to about 1600 metres as a cold front passes through the region leaving 3-5 mm of precipitation. Strong Southwest winds overnight should become light Northwest in the morning.

Avalanche Summary

Loose moist avalanches up to size 1.5 were reported that entrained surface snow in the track, but did not step down to deeper weak layers. Forecast warming on Monday and Tuesday with little or no overnight freezing may result in large avalanches stepping down to the February DPWL.

Snowpack Summary

In the Smith Basin area there is 140 cm below treeline and the top 40 cm was found to be moist and well consolidated. The March crust below was decomposing at this location. The February deep persistent weak layer was down 80 cm and well preserved. Higher up at about 2300 metres the height of snow was a little over two metres. The March crust was not intact at this location and did not result in any shears in snow profile tests. The February DPWL was down 100 cm and was a well defined layer of softer facetted snow below the hard (pencil) snow of the well settled mid-pack. Hard sudden collapse shears were recorded at the interface of the February DPWL. New snow was being transported by the strong gusty winds at the ridgetops. The foot penetration was 25-30 cm, which suggests that there continues to be snow available for transport at higher elevations.In the Elk Valley South the height of snow at 1900 metres was 430 cm. The snow was dry and loose above 1700-1800 metres and moist below where loose wet slides had released on solar aspects. There was a 2-3 cm supportive crust on Southerly aspects above 1900 metres, and no crust on shaded North aspects.

Problems

Wind Slabs

Recent wind slabs have become stubborn to trigger. Rising freezing levels and strong solar radiation may increase the sensitivity to triggering during the forecast warm weather.

Be cautious as you transition into wind affected terrain.>Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

Avalanches releasing on the deeply buried weak layer from early February are still a concern. Strong solar radiation, cornice falls, new loading, or storm slab avalanches in motion are all possible triggers.

Consider the consequences of the terrain if an avalanche steps down to a persistent weakness.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Loose Wet

Forecast rising freezing levels and strong solar radiation may result in loose wet avalanches from steep sun exposed slopes. No overnight freezing may increase the likelihood of this problem for Tuesday.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 7th, 2014 2:00PM