Avalanche Forecast

Issued: Apr 25th, 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, Loose Wet and Cornices.

rupert wedgwood, Parks Canada

Jasper.

Be mindful of the strength of the incoming solar radiation. Temperature increases can occur very rapidly when the sun comes out with a corresponding increase in avalanche danger. Finish your trips early under these conditions.

Summary

Weather Forecast

Temperatures will remain warm overnight with strong Westerly winds at upper elevations. Freezing levels will hover between 2000m - 2200m. Precipitation amounts will be limited to 3mm with the Continental Divide receiving the largest share. More snow if forecast for friday evening and into Saturday at which time temperatures will drop dramatically.

Snowpack Summary

A spring temperature crust up to 15cm thick can be found near the top of the snowpack. Warm temps will prevent a good overnight freeze of the crust which has been found as high as 2600m. Strong Westerly winds will continue to develop slab conditions on Easterly facing slopes particularly if we receive new snow on Friday and Saturday.

Avalanche Summary

With the lack of a good overnight freeze tonight increased wet slides from treeline and below can be expected on Friday. New snow on Friday and Saturday will increase trigger sensitivity of slab avalanche from treeline and above. The extreme Westerly winds and warm temperatures will increase cornice failure with the potential of trigger deep slabs.

Confidence

Forecast snowfall amounts are uncertain on Friday

Problems

Wind Slabs

Strong to extreme Westerly winds along with warmer temperatures and 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 plain.

Carefully evaluate and use caution around thin snowpack areas.Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

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.

Carefully evaluate and use caution around thin snowpack areas.Travel early on frozen crusts before the heat of the day.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Strong to extreme Westerly winds and warmer temperatures 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.Stay well back from cornices.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Apr 26th, 2013 4:00PM