Avalanche Forecast

Issued: Apr 26th, 2013 4:00PM

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

a.l. horton, Parks Canada

Jasper.

Conditions have changed! A spring storm will bring up to 25 cm of snow and strong to extreme SW winds.

Summary

Weather Forecast

A low pressure system will bring up to 25 cm of snow to upper elevations on Saturday. This system will be brought in with strong to extreme southerly winds. The freezing level will begin to fall through the day on Saturday through Sunday, ending up around 2000 m. Cool snowy conditions will continue into the beginning of next week.

Snowpack Summary

Temperatures have been above freezing for the past 36 hours. This has weakened or melted the temperature crust that has been found near the top of the snowpack. New snow and strong to extreme SW winds will build windslabs below alpine and treeline ridgelines. Cornices are large and ready to drop.

Avalanche Summary

No significant avalanche activity was observed in the Icefields today other than numerous thin loose wet slides on steep treeline and alpine slopes.

Confidence

Forecast snowfall amounts are uncertain on Saturday

Problems

Wind Slabs

Strong to extreme Westerly winds along with up to 25 cm of new snow are increasing the avalanche danger into the weekend. South facing slopes should be approached cautiously where buried sun crusts may provide the perfect failure plane.

Use caution in lee areas in the alpine. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Warmer air temperatures and freezing levels into the alpine will prevent a good overnight refreeze of the surface crust. Expect an increased in avalanche activity particularly from thin snowpack areas around treeline on south facing slopes.

Be cautious of sluffing in steep terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Strong to extreme Westerly winds will increase the likelihood of cornice failure. Deep releases from a wet snowpack may run far into the valley bottom.

Extra caution needed around cornices with current conditions.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Apr 27th, 2013 4:00PM