Avalanche Forecast

Issued: Apr 21st, 2013 4:00PM

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

mike eder, Parks Canada

Jasper.

Should the sun come out for extended periods, the avalanche danger could increase dramatically and quickly. Pay attention to the sun and temperatures. Adjust your route if required.

Summary

Weather Forecast

Temperatures are expected to warm up slightly with freezing levels hovering around 1500 meters. The Eastern slopes of the Rockies are expected to have cloud cover with only light snowfall from Tuesday through to Thursday. Winds will be light to moderat predominantly from the Northwest. No significant snowfall is expected.

Snowpack Summary

Spring conditions are mostly solid with up to 15cm of snow on the crust layer. In the alpine, wind slabs exist on lee aspects near ridge tops. Sun crusts are well developed on steep, solar aspects. Overcast skies and cooler temperatures have kept the crusts intact even at lower elevations. This may change later this week if more sun comes out.

Avalanche Summary

No new avalanches were reported today. One avalanche was reported late Friday above the icefalls on the Athabasca glacier which originated from steep, cross loaded gullies in the high alpine. Cooler temperatures and no solar radiation due to cloud cover has reduced natural activity in the last few days.

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Loose Wet

Sunny periods combined with warmer temperatures will increase this avalanche activity from steep solar aspects and gully features.

Minimize exposure to sun exposed slopes when the solar radiation is strong.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

It is that time in the spring when warmer daytime temperatures combined with milder overnight temperatures will make cornices more susceptible to collapsing. They seem larger this year and may still trigger deep instabilities on north aspects.

Cornices become weak with daytime heating, so travel early on exposed slopes.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Wind Slabs

Isolated pockets of wind slab can be found on lee aspects in exposed alpine terrain near ridge crests. The likelihood of triggering avalanches increases when the day heats up or the sun comes out. Test the bond to the underlying crust.

Be careful with wind loaded pockets

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Apr 22nd, 2013 4:00PM