Avalanche Forecast

Issued: Feb 25th, 2017 4:00PM

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

garth lemke, Parks Canada

Jasper.

Cautious decisions are key particularly on large and specific terrain features or those around terrain traps. Forecasters do not have much confidence in the snowpack. Evaluate snow and terrain carefully.

Summary

Weather Forecast

Flurries now to Tuesday. Expect Sunday to be lows of -21 with L-NE winds. Will warm up again slightly Monday to Tuesday.

Snowpack Summary

Windslabs evolving into persistent slab at TL and ALP buried by 5-10cm of new snow. A rain crust is below 1900m. A dense upper snowpack overlies a weak faceted base making for unpredictably dangerous avalanche conditions. Feb 10 SH layer may be 40cm deep yet its reactivity remains dormant.

Avalanche Summary

Nothing new noted on Saturday. Friday's patrol observed 2 avalanches remotely triggered by skiers size 1.5-2 in Columbia Icefield area at 2000m treeline elevation. Two size 2-2.5 noted in the alpine south of Parkers ridge. One was a cross-loaded NW alpine feature, the other was triggered by cornice failure.

Confidence

The weather pattern is stable

Problems

Deep Persistent Slabs

Widespread whumphing and shooting cracks in previously un-skied terrain. It seems to be improving but suspect pockets of weakness waiting for the trigger.

Be aware of thin areas that may propogate to deeper instabilites.Watch for shooting cracks or stiffer feeling snow. Avoid areas that appear wind loaded.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The previous windslabs has evolved into a persistent slab buried under 5-10cm of new snow. It potentially overlies a buried surface hoar from Feb 10 but hard to locate. Be vigilant particularly in sheltered spots preserving the buried surface hoar.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Feb 26th, 2017 4:00PM