Avalanche Forecast

Issued: Apr 24th, 2013 4:32PM

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

rupert wedgwood, Parks Canada

Jasper.

The avalanche danger will rise both rapidly and significantly once the melt freeze crust has melted. This process will occur earlier in the day if the crust does not refreeze well overnight, if it rains or with prolonged intense solar radiation.

Summary

Weather Forecast

A South and Westerly flow will persist until Friday. Precipitation will be limited to flurries and the chance of light rain at lower elevations. The overnight temperatures will alow for refreezing of the melt freeze crust. Freezing levels during the afternoon will reach upper treeline and should the sun come out crustal breakdown may occur earlier.

Snowpack Summary

A spring temperature crust up to 15cm thick can be found near the top of the snowpack. This crust has been found as high as 2600m in the Icefields area. In places it is buried under several inches of new snow. Wind slabs can be found at upper elevations on most aspects due to varied wind direction patterns. Cornices are large and ready to drop.

Avalanche Summary

No recent avalanche activity has been reported today. Cooler temperatures and limited solar radiation due to cloud cover has reduced natural activity in the last few days.

Confidence

Forecast snowfall amounts are uncertain

Problems

Wind Slabs

Isolated pockets of wind slab can be found on lee aspects in exposed alpine terrain near ridge crests. Expect to encounter this condition on most aspects due to recent variable wind directions. Poorly bonded slabs on solar crusts are likely.

Be cautious as you transition into wind affected terrain.Watch for areas of hard wind slab in steep alpine features.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Wet

Cool temperatures and limited direct solar radiations will preserve the melt freeze crust in most locations until mid afternoon. Once gone the avalanche danger will increase rapidly.

Make your travel plans to take advantage of overnight freezing.Start and finish early before the surface crusts melt.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

It is that time in the spring when warmer daytime temperatures combined with milder overnight temperatures will make cornices more susceptible to collapsing. They seem larger this year and may still trigger deep instabilities on north aspects.

Give cornices a wide berth when travelling on or below ridges.Do not travel on slopes that are exposed to cornices overhead.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Apr 25th, 2013 4:32PM