Avalanche Forecast

Issued: Feb 23rd, 2015 8:07AM

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

Lydia Marmont, Parks Canada

Glacier.

Wind slabs are the main concern, watch for loaded pockets around ridge lines. Look up when traveling on the shady side under ridges, keep in mind that the sun could be shining on the other side and weakening cornices above.

Summary

Weather Forecast

The strong ridge of high pressure is expected to hold until at least Wednesday blocking any new snowfall. Today will bring a mix of sun and cloud with freezing levels rising to 1600m and light NW winds at ridgetop. Clouds should build slowly over the next few days with small amounts of precipitation expected to begin on Wednesday.

Snowpack Summary

Below 1900m a light dusting of new snow sits on a hard crust. Up to 2200m 15-20cm of light snow sits on the Feb 18 crust/ surface hoar layer. The Feb 14 crust is down 20-25 and is up to 10cm thick. Soft wind slabs have formed on all aspects in exposed areas at treeline and above. Persistent weak layers down 1-1.5m are stubborn to trigger.

Avalanche Summary

1 Size 2 loose wet avalanche was observed yesterday in the highway corridor from 2590m on a South aspect. There were reports yesterday of a large cornice fall (Size 3) off the north face of Bonney that didn't trigger a slab.

Confidence

Problems

Wind Slabs

Pockets of wind slab in lee features can be triggered by riders. Wind slabs up to 50cm thick could propagate on a buried crust up to 2200m and surface hoar above that. Cornices are weakening with the temperature swings and are becoming more touchy.

Watch for whumpfing, hollow sounds, and shooting cracks.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Persistent weak layers down 1 to 1.5m will need a large load such as a cornice failure to be triggered. A light load may be able to trigger them from shallow areas. Heads up when traveling on slopes that could be affected by weakening cornices.

Be aware of thin areas that may propogate to deeper instabilites.Extra caution needed around cornices with current conditions.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 4

Valid until: Feb 24th, 2015 8:00AM