Avalanche Forecast

Issued: Apr 11th, 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.

jasper snow safety, Parks Canada

Jasper.

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

Summary

Weather Forecast

Thursday will be mainly cloudy with isolated flurries, trace precipitation, High -3 C, wind southwest:10-25 km/h, freezing level 1900 metres. Friday will be flurries and 9 cm of snow, low -11 C and high -5 C, wind southwest 20 km/h gusting to 50 km/h, freezing level 1600 metres. Saturday will bring sun and flurries, low -6 C and high -3 C.

Snowpack Summary

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

Avalanche Summary

No patrol Wednesday. Skiers released a cornice to test Ulr / terminator chute #5 today and released a healthy size 2 avalanche. This is a steep N facing chute dropping into Whistler creek drainage from the backside of Marmot basin.

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Persistent Slabs

Persistent slabs sitting on facets on Northerly aspects continue to show isolated signs of reactivity. Triggering may occur from shallow snowpack areas some distance out.

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

The snowpack in shallow spots requires very little in the way of ambient heat to weaken it to point of triggering. Solar radiation speeds up this process dramatically.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

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.

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 12th, 2018 4:00PM