Avalanche Forecast

Issued: Apr 6th, 2019 4:39PM

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.

Ruari Macfarlane, Parks Canada

Jasper.

Pockets of new Wind Slab. A tricky Persistent Slab avalanche problem is awakening in the South of the region - take a cautious approach to shady alpine terrain (the best skiing).

Summary

Weather Forecast

5cm snowfall forecast for Parkers Ridge Saturday night, and a trace for the Jasper area. Strong SW winds overnight, slowly easing to Moderate by Sunday. Mainly sunny for Jasper, but mainly cloudy for the Icefields region. Freezing level 1700m, Treeline Low -7, High -4. Mon/Tues: Continued sun/cloud/flurries, Freezing level 2000m, light winds

Snowpack Summary

Regular small snowfalls are settling quickly, over a melt-freeze crust everywhere except N aspects above treeline. Small windslabs are building on lee slopes (alpine and treeline). It's still a winter snowpack on alpine North aspects, with facets still producing sudden test results down 50cm, and whumphing in the South of the bulletin region.

Avalanche Summary

On Saturday, a road patrol to Maligne Lake did not see any new avalanches.On Friday, A recent Large (Size 2.5), natural Persistent Slab was noted on a steep NE facing alpine slope, in the Icefields area. Previous persistent slab activity was noted on N & NE aspects above 2700m on Mt Wilson. A few small loose drys were observed near Marmot Basin.

Confidence

Due to the number of field observations

Problems

Wind Slabs

Small, reactive windslabs already exist in immediate lees in the Alpine. With strong SW winds Saturday night, this problem may extend down to treeline on Sunday, especially along the Parkway where 5cm of new snowfall is expected overnight.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Choose terrain that offers options, so you can avoid visible Wind Slabs.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Persistent Slabs

Natural avalanche activity, whumphing and test results indicate that small amounts of loading and sustained mild temperatures may be awakening a Persistent Weak Layer: facets buried 50cm down. This is more prevalent at the Columbia Icefields & South.

Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.Minimize exposure to terrain traps where the consequences of an avalanche could be serious.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 2.5

Valid until: Apr 7th, 2019 4:00PM