Avalanche Forecast

Issued: Jan 6th, 2021 8:00AM

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

Chris Gooliaff,

Glacier.

Human-triggering of storm slabs is being reported throughout the park. All incidents seem to be from areas where slightly more wind has tightened the surface. Watch for whumphing/cracking of the snow surface for clues of instability.

Summary

Weather Forecast

One last pulse of snowfall today, then a dry period for a few days.

Today: flurries, 5-10cm, alpine high -5*C, mod SW winds

Tonight: cloudy, alpine high -9*C, light S winds

Thurs: cloud with sunny periods, alpine high -4*C, light S winds

Fri: sun and cloud, alpine high -1*C, light S winds

Snowpack Summary

In the past 4 days, 90cm of snow, SW winds, and mild temps have created a surface storm slab. This sits on a surface hoar layer, buried Dec 26, which is preserved in sheltered areas at and below treeline. The Dec 13 surface hoar can still be found down 120cm and the Dec 7 crust/facet/surface hoar (aspect/elevation dependent) layer is down 135+cm.

Avalanche Summary

Human-triggered activity seems to be confined to areas at and below treeline that have had wind to create a reactive surface slab. A sz 2 skier accidental on the east end of the park was reported on the MIN, while more activity was observed in Puff Daddy and Napoleon Spur on Monday.

Natural activity overnight on Macdonald and Tupper to sz 2.5.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Storm Slabs

90cm of snow in the last 4 days, SW winds, and mild temps have built a widespread storm slab. A Dec 26 surface hoar layer persists below this slab, 70-90cm deep, in sheltered areas at treeline and below.

The new snow will require several days to settle and stabilize.
Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

Avalanche activity this weekend shows that large triggers (such as cornices and storm slabs) could still cause very large avalanches on these layers. These lower layers could wake up with a storm slab overloading them.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Be wary of large slopes that did not previously avalanche.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Loose Dry

Plenty of loose snow exists in sheltered locations at and below treeline. Skier triggered sluffs have the potential to collect significant mass and bury a person in a terrain trap. Sluff management is essential today.

If triggered dry loose point releases can form deeper deposits in terrain traps.
Be careful of loose dry power sluffing in steep terrain..

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Jan 7th, 2021 8:00AM