Avalanche Forecast

Issued: Apr 12th, 2018 4:00PM

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

garth lemke, Parks Canada

Jasper.

Good skiing can be found close to treeline on sheltered north facing terrain as winter conditions persist. Evaluate specific terrain features before committing as we are in a low probability high consequence situation.

Summary

Weather Forecast

Friday will be flurries and 11 cm of snow, high -6 C, wind southwest 20 km/hr, freezing level 1700m. Saturday will bring flurries, 9cm of snow, low -7 C and high -5 C, Southwest winds 20km/hr gusting 50, freeing level 1800m. Sunday is forecast to be flurries, 10cm of snow, low -8 and high -2 C, light South winds, and freezing level 2100m.

Snowpack Summary

Wind slabs and wind effect is found in open areas treeline and above. The upper snowpack is a variable 25 to 80 cm thick slab that sits on weak FC crust layers in the mid-pack. Depth hoar persists near the ground.

Avalanche Summary

No patrol Thursday. Skiers released a cornice to test Ulr / terminator chute #5 Wednesday and released a healthy size 2 avalanche. See the MIN report. This is a steep N facing chute dropping into Whistler creek drainage from the backside of Marmot basin. Another group observed sz 2's 48 hours old in Bald hills zone on Wednesday.

Confidence

Forecast snowfall amounts are uncertain on Friday

Problems

Persistent Slabs

Persistent slabs sitting on facets on Northerly aspects continue to show sporadic signs of reactivity. The slab sits on buried temperature crusts on South aspects. Triggering may occur from shallow snowpack areas some distance out.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Moderate southerly winds in the alpine continue to build pockets of wind slab. Once triggered, these slabs may trigger deeper releases running far into the valley.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Apr 13th, 2018 4:00PM