Avalanche Forecast

Issued: Apr 25th, 2018 4:09PM

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, Persistent Slabs and Cornices.

rupert wedgwood, Parks Canada

Jasper.

The avalanche danger is moving into the extreme ranger over the next few days. With limited overnight freezing forecasted, anticipate the danger to remain in the high range into the late evening.

Summary

Weather Forecast

Very warm temperatures are forecasted with freezing levels extending high into the alpine, 3,700m. Virtually no overnight recovery of the snowpack is expected once out of the valley bottom. An inversion may make for better AM travel in the valley bottom. Pack your sun block.

Snowpack Summary

Moist snow extends to treeline on all but the most Northerly slopes. On Southerly slopes this continues into the alpine. Persistent slabs can be found on most aspects at treeline and above. These have been reactive to large triggers like cornice failures. Below 1,900m the snowpack is going isothermal on a daily basis.

Avalanche Summary

The spring avalanche cycle will be in full swing over the next few days. Large and destructive avalanche can be expected from all elevations and running far into the valley bottom. Without an overnight freeze forecasted these events will start early, perhaps before midday.

Confidence

Problems

Loose Wet

No overnight crust formation is expected at treeline and above. With most of the snowpack below 1,900m being isothermal expect these avalanches to start early on solar slopes at all elevations.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.Conditions are Extreme. Avoid backcountry: stick to ski resorts or trackset cross country trails.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 3

Persistent Slabs

With warm temperatures and solar radiation these events are likely to increase over the next few days from all aspects in the sun. Good triggers are falling sections of cornices. These events can run far into the valley below

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1.5 - 3.5

Cornices

All cornices should be considered unstable a this time. Stay away from them and away from terrain below them. Rising temperatures are causing cornices to fall triggering slopes below. Give them a wide berth.

Pay attention to overhead hazards like cornices which could easily trigger persistent slabs.Avoid steep slopes below cornices.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Very Likely

Expected Size

1.5 - 3

Valid until: Apr 26th, 2018 4:09PM