Avalanche Forecast

Issued: Jan 13th, 2013 4:00PM

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

garth lemke, Parks Canada

Jasper.

Winds continue to build 10-15cm thick slabs. There reactiveness is slowly increasing as some whumphing and cracking was noted on Saturday. Spike in temperatures and high winds may increase the danger Monday to Wednesday.

Summary

Weather Forecast

Monday: warm front, 6mm precipitation, isolated freezing rain, temps increasing yet remain below 0. Ridge winds 50-80km/hr NW. Tuesday: Sun, temperature spike, alpine plus temps, 50-70km/hr NW winds. Wednesday: cooler temps, 125km/hr alpine and 50km/hr treeline winds. Good confidence on warming but low confidence on exact temperature values.

Snowpack Summary

Winds have formed thin slabs out of Wednesday's 30cm storm snow at alpine and exposed treeline locations. The snowpack remains thin and facetted at lower elevations. Above tree line its thicker and supportive. A buried a surface hoar-surface facet layer 30cm down from Jan 6 is lurking but remains stubborn.

Avalanche Summary

Thursday's explosive control on low elevation targets released several size 2 slabs and loose snow avalanches. Natural activity has remain limited since then as cold temperatures locked it down. No new natural activity was noted Saturday; however, we observed pockets of 10-15cm thick windslabs, minor whumphing and cracking. No Sunday patrol.

Confidence

Freezing levels are uncertain on Monday

Problems

Wind Slabs

Wednesday's 30cm storm has evolved into a windslab on a variety of aspects. This may cover a buried surface hoar from Jan 6 yet its remained unreactive or stubborn. Minor whumphing and cracking was noted on Saturday in the alpine.

Make observations and assess conditions continually as you travel.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Dry

Where wind has not affected the slope, 30cm of cold unconsolidated snow is sluffing out of steep terrain. They have been observed to pick up enough mass to be a concern to skier and climbers particularly when terrain traps are involved.

Be cautious of sluffing in steep terrain.Sluffs may trigger deeper instabilities.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 14th, 2013 4:00PM