Avalanche Forecast

Issued: Jan 17th, 2018 4:00PM

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

max darrah, Parks Canada

Jasper.

Strong winds and the potential for heavy snowfall will change the landscape and increase the avalanche danger rapidly. New windslabs will be touchy, and the increased load may awaken midpack layers of concern.

Summary

Weather Forecast

Steady snowfall overnight on Wednesday, with models predicting anywhere from 6mm to 35mm through to Thursday evening with strong SW ridgetop winds. After this, precipitation is expected to taper, and winds to moderate.

Snowpack Summary

10-15cm of snow from Jan 10 has blown into thin slabs TL and above. Midpack is faceted with several distinct crusts in the mid to lower snowpack. There is a layer of concern (Dec 15) composed of facets and surface hoar that can be found down approximately 15-30cm. This layer has been active in isolated areas, producing slab avalanches to size 2.

Avalanche Summary

Limited visibility, but one report of a size 2 loose dry avalanche on Mt Wilson that originated in the alpine and ran 400m to the forest below.

Confidence

Forecast snowfall amounts are uncertain on Thursday

Problems

Wind Slabs

New snow and moderate to strong SW winds will rapidly build new windslabs. Forecasted amounts are uncertain, and hazard will be directly related to the amount of snow that arrives.

Use caution in lee areas. Recent wind loading has created fresh slabs.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Persistent Slabs

Isolated slab avalanches to size 2 were reported by field teams on Monday. They were triggered by loose snow avalanches from the cliffs above and solar input. The concern is that additional load may increase activity on midpack weak layers.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Loose Dry

New snow landing on loose facets has the potential to entrain and create big sluffs.

The new snow will require several days to settle and stabilize.Avoid travelling on ledges and cliffs where sluffing may have severe consequences.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Valid until: Jan 18th, 2018 4:00PM