Avalanche Forecast

Issued: Jan 2nd, 2019 8:07AM

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

mark herbison, Parks Canada

Glacier.

A significant winter storm is heading our way today and will increase the Avalanche Hazard over the next few days. Expect Artillery Avalanche Control and Highway closures on Thursday.

Summary

Weather Forecast

A significant storm system will arrive today and persist until Friday evening with a forecasted snowfall amount of 80cm with moderate to strong winds. Today we will see ~10cm of snow, an alpine high of -7 and 30kph Southerly winds. Snowfall amounts are forecasted to be; 20cm tonight, 30cm tomorrow, 20cm Friday... Wahoo!

Snowpack Summary

40cm of storm snow has been redistributed by moderate southerly winds. The Dec 9 and Nov 21 interfaces are down ~120-160cm and still producing hard/sudden test results, and can be triggered in shallow/rocky areas. The mid to lower snowpack is generally well settled and rounding. Decomposing early seasons crusts are still present at/near the ground.

Avalanche Summary

A skier triggered size 3 avalanche from Bruins Ridge nearly swept 2 skiers over cliffs into 8812 Bowl on Sunday. A field team found the avalanche slid on the Nov 21 sun crust, triggered from a shallow area. The crown ranged from 30-150cm in thickness, 40m wide, and 300m in length. No new avalanches observations or reports yesterday.

Confidence

Problems

Storm Slabs

A new storm slab will develop over the day with the incoming storm and bury old wind/storm slab. 40cm of settled storm snow has been redistributed by moderate southerly winds and formed pockets of wind slab at ridge line and cross loaded features.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Assess start zones carefully and use safe travel techniques.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2.5

Persistent Slabs

The Dec 9/Nov 21 persistent weak layers are down ~120cm+ and consist of surface hoar, facets, or a sun crust depending on aspect and elevation. Sunday's Bruins Ridge avalanche was triggered on this layer in a shallow, wind-swept area.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Dig down to find and test weak layers before committing to a line.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 3rd, 2019 8:00AM