Avalanche Forecast

Issued: Apr 11th, 2013 4:00PM

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

Parks Canada max darrah, Parks Canada

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Summary

Weather Forecast

Good overnight freeze for Thursday night, with freezing levels hovering around 1200m during the daytime for the next few days.  Winds light to moderate from the SW with convective precipitation expected through the weekend with up to 15mm of precipitation possible by Sunday evening.

Snowpack Summary

Melt freeze crust below 2000m on all aspects, new windslab (10cm thick) found on lee aspets at exposed ridgecrests above treeline.  10cm of new snow in past 24 hours, rapidly settling and moist below 2200m.  Sun crust on solar aspects.

Avalanche Summary

Several natural slab avalanches observed in past 24 hours in both the Columbia Icefield Area and Maligne Lake district.  Size 2 - 2.5, on lee aspects below ridgelines between 2200-2400m.  Several large cornice failures reported, and some of these did trigger storm slabs on the slopes below to size 2.  Loose dry point releases on steep N terrain.

Confidence

Problems

Wind Slabs

An icon showing Wind Slabs
Recent winds have formed new windslabs on lee aspects below ridgecrests above treeline.  These slabs are roughly 10-15cm thick, and where they are sitting on previous crusts may be reactive to skier traffic.
Be cautious as you transition into wind affected terrain.The recent snow may now be hiding windslabs that were easily visible before the snow fell.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

An icon showing Cornices
Several cornice failures were observed in the past 48hours and some of these did trigger storm slabs on the slopes below up to size 2. 
Extra caution needed around cornices with current conditions.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Loose Dry

An icon showing Loose Dry
Recent snowfall came in warm and stuck to steep rock and ice.  This terrain will shed this snow with daytime heating.
Avoid travelling on ledges and cliffs where sluffing may have severe consequences.Finish ice climbs early in the day before the temperature rises.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Apr 12th, 2013 4:00PM

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