Avalanche Forecast

Issued: Apr 17th, 2013 8:06AM

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 Persistent Slabs.

jon schleiss, Parks Canada

Glacier.

Wind slabs in the alpine and treeline have been easy to trigger for skiers and boarders. Be cautious when traveling above the treeline. Today is the last day of the permits for the 2012-2013 season.

Summary

Weather Forecast

Sunny with cloudy periods today, followed by cloud and snow flurries that begin tonight and through tomorrow. This should be followed by a series of weak storms on Friday and into the weekend with rising freeze lines.

Snowpack Summary

40-50cm of settling storm snow over the April 3rd crust which varies in thickness due to strong winds at tree line and alpine elevations. Below this crust in most areas the snowpack is isothermal.

Avalanche Summary

Monday, a Skier Accidental, size 3.0 on the east face of Mt Swanzy, depth 100cm, 150m wide, suspect April 3 crust. Skiers were not involved, and later the same day a Skier Accidental, size 2.0, Forever Young couloir, depth 30cm, 40m wide ran to 2/3 fan. Skier got taken down onto the fan before he managed to self arrest.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Problems

Wind Slabs

Winds over the last week have been strong and have caused wind slabs on all aspects at treeline and in the alpine. On solar aspects this interface may be poorly bonded where surface hoar had formed on buried sun and temperature crusts.

Dig down to find and test weak layers before committing to a line.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 3

Loose Wet

Clear skies and freezing levels rising to 1700m today will increase the avalanche hazard on sun affected slopes. Pay attention to overhead cornice hazard even on north facing slopes as cornices are weak and may be getting heated by the sun above.

Cornices become weak with daytime heating, so travel early on exposed slopes.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

Large avalanches are still being human triggered as was demonstrated Monday occurring on deeper instabilities. Shallow, rocky areas where the snowpack is thin and weak are most likely where they can be triggered.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 3

Valid until: Apr 18th, 2013 8:00AM