Avalanche Forecast

Issued: Apr 9th, 2018 4:00PM

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

jonas hoke, Parks Canada

Jasper.

If you find signs of reactivity in the persistent slab share your findings on the MIN, it could save someone else from getting surprised...

Summary

Weather Forecast

A series of weak fronts pass over the Park under a SW flow, bringing warm unsettled weather with some precipitation. Tuesday we will see sunny breaks in the morning, followed by flurries in the afternoon/evening (up to 7 cm snow/rain below 2100m). Alpine temps will be a low of -7C, high 0C. Ridge winds will be light (gusting strong) from the SW.

Snowpack Summary

Fresh wind slabs continue to build in high alpine areas. In the upper snowpack a 25 to 80 cm thick slab bridges the March 15th persistent weak layer (facets on polar, sun crust on solar). Recent warming has promoted rounding in the upper snowpack, however the mid and lower snowpack remain weak and facetted from this winters prolonged cold periods.

Avalanche Summary

We received a report of large slab avalanche on Monday in the North bowl of Whistler peak. It was remotely triggered from the ridgetop and failed as a size 2.5 persistent slab (suspect Mar 15th interface), 60cm deep by 75m wide, which ran down to treeline. Some size 1 moist surface sluffing was noted on steep solar aspects on Sunday.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Persistent Slabs

Persistent slabs sitting on facets on Northerly aspects continue to show isolated signs of reactivity. Travel on large Northerly features at treeline and in the alpine is not recommended.

Carefully evaluate terrain features by digging and testing on adjacent, safe slopes. Avoid steep convexities or areas with a thin or variable snowpack.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Loose Wet

Expect natural avalanche activity during periods of rain.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Wind Slabs

Moderate south west winds in the alpine continue to build fresh pockets of wind slab.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee and cross-loaded terrain near ridge crests.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Apr 10th, 2018 4:00PM