Avalanche Forecast

Issued: Nov 25th, 2017 4:00PM

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

garth lemke, Parks Canada

Jasper.

Developing windslab at Treeline and above on Saturday. 25+ cm possible with incoming storm on Sunday afternoon will increase hazard to High on Monday.

Summary

Weather Forecast

Flurries Saturday with mod SW winds . Alpine Temperatures up to -5. Sunday - snow with increasing accumulation through the afternoon with 25 cm possible by early Monday morning, freezing level rising to 2200m then falling to valley bottom as storm passes. Moderate SW winds will accompany this storm.

Snowpack Summary

Cooler temperatures have formed a surface crust from the previous moist snow below 2300m. A persistent slab between 40cm - 200cm thick sits over the Halloween Crust low in the pack. This crust can be found up to 2,700m depending on its location and is between 20cm - 40cm above the ground. Wind slabs likely exist in the upper alpine.

Avalanche Summary

No field patrol on Friday. Thursday had numerous persistent size 2.5 slab avalanches. They failed at treeline and in the lower alpine as a result of warm temperatures, rain and additional snow loading. On Nov. 22nd a field team remote triggered 3 simultaneous size 2 persistent slabs 60-150m away on either side of the wind scoop at parkers ridge.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Sunday

Problems

Persistent Slabs

This is a complex problem which is hard to assess and predict. Give yourself a wide margin and make conservative terrain choices.

Be wary of slopes that did not previously avalanche.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Wind Slabs

Be wary of areas where new snow transport has created pockets of windslab. Watch for sudden changes in texture and hardness. Typically occurring on lee aspects but may be influenced by local terrain.

Use caution in alpine lee areas. Recent snow is available for transport given the current winds.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Nov 26th, 2017 4:00PM