Avalanche Forecast

Issued: Apr 9th, 2017 7:39AM

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

chris gooliaff, Parks Canada

Glacier.

The winter snowpack still rules the alpine while spring conditions are starting to take effect in the valley bottoms. Watch for surface slabs and massive cornices up high, and be aware of loose, wet avalanches in the valley at the end of your day.

Summary

Weather Forecast

Convective cells will be the main story today, bringing isolated flurries and complete white-out in the alpine for brief periods, then followed by a mix of sun and cloud. Freezing levels will rise to 1500m by the afternoon, alpine high of -6*C, and light westerly ridge-top winds. Monday will see a mix of sun and cloud with slightly warmer temp's.

Snowpack Summary

15cm of new snow fell in the last 2 days with strong southerly winds accompanying the 1st wave of snow, then backing down to light winds. Below the new snow lies 30cm of moist snow with several embedded temp crusts. Deeper in the snowpack, old persistent weak layers that include crusts and facets have been reactive to large triggers like cornices

Avalanche Summary

Numerous slab avalanches up to size 3 were triggered by artillery control in the highway corridor yesterday. All slabs were in the upper storm snow, failing on sun or temperature crusts, and were not observed to be digging deeper into the snowpack.

Confidence

Problems

Storm Slabs

30cm of moist snow overlies a crust everywhere other than high elevation N'ly aspects. Winds have been shifting directions and will have formed deeper pockets on lee slopes. These slabs are reactive to human triggering.

Watch for shooting cracks or stiffer feeling snow. Avoid areas that appear wind loaded.Choose well supported terrain without convexities.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

Cornices and smaller avalanches have recently triggered deep, persistent weak layers. The resulting avalanches have been observed to run well into the valley bottoms. With daytime warming, the likelihood will increase.

Space out and travel quickly through runout zones of avalanche paths.Pay attention to overhead hazards like cornices which could easily trigger persistent slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Wet

At treeline and below, rain has saturated the snow that overlies a series of crusts. The refreeze overnight will break down with day-time warming, and solar input will rapidly weaken the crust during sunny periods.

Use safe ski cutting techniques before entering ski run. Use extra caution on solar slopes or if the snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 10th, 2017 8:00AM