Avalanche Forecast

Issued: Apr 21st, 2017 5:06PM

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

a.l. horton, Parks Canada

Jasper.

The Maligne Road was closed Friday afternoon due to loose wet avalanche hazard. We are on the verge of spring conditions. Travel early and be off slopes by mid-day.

Summary

Weather Forecast

Clear and cold overnight on Friday shouldÂ develop a melt freeze crust into Saturday morning.Â Freezing level above 2000 m both Saturday and Sunday afternoon.Â 10 cm snow possible on Sunday.Â A cloudy cooler weekend ahead.

Snowpack Summary

10-20 cm snow overnight has rapidly settled.Â The upper snowpack is moist or wet depending on aspect and elevation.Â The mid-pack is solid and bridging the weak base. The bottom 30cm of the snowpack consists of weak facets and depth hoar mixed around the Nov rain crust. Below 1500m there is no snow.

Avalanche Summary

Numerous loose wet avalanches to size 2 tree-line and below on Friday.Â Maligne Road closed Friday afternoon due to increasing loose wet avalanche hazard.

Confidence

Freezing levels are uncertain on Saturday

Problems

Loose Wet

A melt freeze crust will loose strength by Saturday afternoon as freezing level rises into tree-line.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Start and finish early before the surface crusts melt.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

The deep instability could be triggered by a cornice failure. It is well bridged by a solid mid-pack; however, consider this problem becoming more active particularly on South aspects as the day warms up or the sun comes out.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Cornices

Cornice failures are still being noted on West aspects 2500-2800m. Give them a wide berth as their failure is hard to predict but increases with sun, warmth, wind-loading, or new snow.

Avoid travel on slopes that are exposed to cornices overhead.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 22nd, 2017 4:00PM