Avalanche Forecast

Issued: Mar 23rd, 2017 4:58PM

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

rupert wedgwood, Parks Canada

Jasper.

Several triggers are at play including solar radiation, wind loading and falling cornices. Pay close attention to changing condition, particularly warming, after all it is spring time.

Summary

Weather Forecast

Unsettled weather with a SW flow L-S winds. Tree line highs -5, Lows -10. Some sunny periods and up to 10cm of snow. Icefields freezing level between 1,450m and valley bottom.

Snowpack Summary

Thick wind slabs at and above treeline which stiffen into alpine. Large cornices are present. The mid-pack has several weaknesses but is providing some bridging strength above the weak base. This is highly faceted with a lingering rain crust and depth hoar below. On southerly slopes a melt freezing crust is developing as the pack warms.

Avalanche Summary

Although the visibility was poor several new slab avalanches were recorded at treeline and into the alpine. A class 3 triggered by a falling chunk of cornice on a NE facing slope. A size 2 from a S facing slope was likely triggered by solar radiation. A skier appeared to have triggered another size 2 on a N slope.

Confidence

Timing or intensity of solar radiation is uncertain on Saturday

Problems

Cornices

Large cornices on lee features with some visibly detached. Those that may release would likely trigger a large avalanche. Give them a wide berth.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

Significant snow is available for transport at treeline and above as witnessed at the Icefields today. Avalanche to size 2.5 have been observed and may step down to deeper layers running far into the valley below. Bonding appears to be improving.

Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Deep Persistent Slabs

The lower snowpack is riddled with weaknesses particularly where the snow is shallow over rocky terrain. Today a large cornice failure triggered a size 3 slab on a NE treeline feature. Debris is running far into the valley bottom.

Be careful with low angle slopes that may not normally be a concern.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Mar 24th, 2017 4:00PM