Avalanche Forecast

Issued: Apr 9th, 2014 4:46PM

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

rupert wedgwood, Parks Canada

Jasper.

Pay Close attention to daytime warming and wind slab development. Good skiing can be found between 2,300 - 1,800 m in sheltered lower angle terrain.

Summary

Weather Forecast

Below freezing overnight temperatures into the weekend with day time freezing levels not extending into the alpine. Some snow may arrive on Friday and into the weekend. Winds will be westerly over the next 36 hours.

Snowpack Summary

At treeline and below warming temperatures and rain has increased the temperature of the snowpack. Moist snow in the upper pack can be anticipated. Surface crusts will form when temps drop. Solar facing slopes close to treeline may have buried crusts with slab snow above. Deeply buried weaknesses near ground. Windslabs in the alpine & treeline.

Avalanche Summary

Slab avalanches observed Tuesday and Wednesday up to size 2.5 from treeline and low alpine. All events are stepping to ground. Most are being triggered by wind loading with one cornice failure. Strong WSW winds are developing wind slabs. Afternoon warming and solar radiation is producing point and wet slab releases from below treeline.

Confidence

Timing or intensity of solar radiation is uncertain on Thursday

Problems

Deep Persistent Slabs

Most avalanches regardless of initial form are stepping down to ground. These are most common from shallow snowpack areas where there is little bridging strength in the midpack and the thermal energy is greatest. Rocky areas are also dicey.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Wind Slabs

Strong South and Westerly winds are transporting the 10-15cm of new snow from the 8th. Rain fell below 1,800m. Field tests at 2,300m produced an easy shear above an old sun crust on the 9th. At lower elevations the slab is less well developed.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

Solar effect and day warming will destabilize the snowpack on all slopes in the valley bottom. The danger will increase as it does. Travel below 1700m will be ugly. With increasing elevation and slopes that don't face south this effect will diminish.

Avoid shallow snowpack areas where triggering is more likely.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Apr 10th, 2014 4:00PM