Avalanche Forecast

Issued: Apr 22nd, 2015 4:00PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Cooler temperatures forecasted for the next few days with a valley bottom freeze tonight. We should see wet avalanche activity taper off tomorrow.

Summary

Weather Forecast

Valley bottom freezing levels forecasted for tonight with clear skies, except for along the Wapta where mainly cloudy skies are expected. Thursday will be a mix of sun and cloud with alpine highs around 0 with light west wind. The couple of days will be cooler than Monday and Tuesday.

Snowpack Summary

Supportive crust on solar aspects in morning which are deteriorating by mid day. High elevation north aspects still have dry snow. Mid pack is well settled with no significant shears. The basal facets remain the main weakness in the snowpack, but we expect only large loads or a dramatic rise in temperatures to cause failures on this layer.

Avalanche Summary

A natural wet slab avalanche cycle occurred on all aspects at treeline and above late Tuesday afternoon and into the evening . Slabs were up to size 3 and were 40-60 cm deep.

Confidence

Problems

Cornices

Cornices failures, combined with the hot temperatures, have the possibility to triggering the deep basal layers.

Extra caution needed around cornices with current conditions.Cornices become weak with daytime heating, so travel early on exposed slopes.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Wet Slabs

Wet slabs have been occurring in the heat of the day late afternoon-evening. They are mostly failing on a layer 40-60 cm down or in some cases scrubbing down to the ground. It will become less reactive with the cooler temperatures forecasted.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Loose Wet

While the forecast suggests slightly cooler temps with cloud cover, any short burst of solar energy late in the day will induce wet avalanches.

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

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Apr 23rd, 2015 4:00PM