Avalanche Forecast

Issued: Apr 18th, 2018 4:08PM

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

rupert wedgwood, Parks Canada

Jasper.

Good skiing at treeline in sheltered terrain. Avoid those slopes with cornices overhead

Summary

Weather Forecast

Freezing temps overnight to the valley bottom. Solar radiation can be expected periodically throughout tomorrow with freezing levels increasing to 2,200m and alpine highs of -3C. Wind will be mostly light and from the SW. Overnight on Thursday the valley bottom temps will remain above freezing allowing for limited overnight recovery on Friday.

Snowpack Summary

Below 1,900m the snowpack is isothermal. Sun or temperature crusts extend to treeline and continued into the alpine on southerly slopes. Persistent slabs can be found on most aspects at treeline and above . These have been most reactive recently on Northerly facing terrain. Soft windslabs have been developing and are up to 40cm deep.

Avalanche Summary

No reports of avalanche today. Increasing freezing levels and direct solar radiation will produce isothermal slides below treeline. Solar input will trigger avalanches into the Alpine from terrain where snow coverage is thin and near rock outcrops on steep south facing slopes. Small sluffs have the potential to trigger deeper instabilities.

Confidence

Freezing levels are uncertain

Problems

Wind Slabs

Although mostly thin some wind slabs are up to 40cm thick in alpine terrain. Solar radiation and cornice collapses can trigger these events. Once triggered the potential to trigger deeper weaknesses exists resulting in larger avalanches.

Use caution in lee areas. Recent wind loading has created wind slabs.Use caution on open slopes and convex rolls

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Pay close attention to the effect of solar radiation and daytime warming on the snowpack underfoot and overhead. Point release from rocks and cliffy terrain can trigger isothermal snow below. This will be of most concern in the late afternoon.

Avoid terrain traps, such as gullies, where the consequences of a small avalanche could be serious.Use extra caution on solar slopes or if the snow is moist or wet.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 1.5

Persistent Slabs

40-100+ cm thick slabs overlie preserved facetted crystals on N aspects, these have been reactive recently.

Pay attention to overhead hazards like cornices which could easily trigger deep slabs.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 19th, 2018 4:00PM