Avalanche Forecast

Issued: Dec 14th, 2012 4:00PM

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

garth lemke, Parks Canada

Jasper.

Moderate danger rating specifies human triggered avalanches remain possible. Now is not the time to jump into big lines.

Summary

Weather Forecast

Next few days will be mainly dry, seasonal temperatures, light winds, and very light flurries.

Snowpack Summary

There is great variation in depth and location of the wind slabs. They continue to build and harden from gusting moderate to strong SW winds. These slabs appear to have bonded well. In windswept areas in the alpine and at tree line, the November rain crust has been exposed along with dirt and rocks. Cornices are well developed.

Avalanche Summary

No new avalanches have been observed or reported since the end the cycle that ended on Monday. In that cycle, slab avalanches to size 3 were observed on NE aspects at alpine and tree line elevations, several stepped down to the basal facet layer. Large cornice failure triggered large avalanches on the basal facet layer as well.

Confidence

The weather pattern is stable

Problems

Wind Slabs

Pockets of wind slabs that vary in hardness are present on all open lee slopes. No new avalanches have been observed and field tests show that these slabs have bonded well in most locations.

Avoid unsupported slopes.Choose well supported terrain without convexities.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Deep Persistent Slabs

Large triggers such as cornice failures have triggered this weakness on SE to NE aspects in the alpine.

Avoid steep slopes below cornices.Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Dec 15th, 2012 4:00PM