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 Loose Wet, Cornices and Deep Persistent Slabs.

garth lemke, Parks Canada

Jasper.

Summary

Weather Forecast

Variable cloud and light West winds for Thursday and Friday. Freezing level 1000m Wednesday night rising to 2000m for Thursday and Friday during the day.

Snowpack Summary

Warm temps have softened up the snow surface into spring conditions. At treeline, lee aspects have a series of windslabs sandwiched with thin weaknesses in the upper snowpack. A strong midpack bridges over weak basal facets on Northerly aspects at treeline and above.

Avalanche Summary

Loose wet avalanches to size 2.5 are occurring at most elevations in the afternoons. Some running on crusts and others scouring to ground. Cornice failures to size 2.5 have occurred on North to East aspects. One size 3 slab with 2 m crown was observed on indian ridge yesterday. Time to put full depth avalanches on the radar.

Confidence

Problems

Loose Wet

As temperatures warm up so does the potential for loose wet avalanches. It may be enough to trigger deeper basal layers on steeper unsupported slopes.

Watch for terrain traps where small amounts of snow will acumulate into deep deposits.Be very cautious with gully features.

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

Cornices are large and can collapse anytime. This is a trigger that could initiate a full depth avalanche. Pay attention to what is above and avoid cornice exposed slopes.

Do not 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.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Deep Persistent Slabs

Time to put full depth avalanches on the radar. The potential for this is related to extent of overnight recovery, large triggers such as a cornice failure, and daytime warming. This increases as spring conditions progress.

Be aware of the potential for large, deep avalanches.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

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