Avalanche Forecast

Issued: Mar 31st, 2015 9:46AM

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

ghelgeson, Avalanche Canada

South Rockies.

Warmth remains the main driver of avalanche hazard as we shift into a more spring like pattern. Minimize your exposure to large slopes if the snowpack is becoming moist or wet.

Summary

Confidence

Fair

Weather Forecast

Wednesday: Freezing level hovering around 1500m. Partly cloudy skies all day. Moderate W winds at treeline, Strong W winds at ridgetop. No significant precipitation.Thursday: Freezing starting near 1200m, rising to about 1600m in the afternoon. Partly cloudy skies. Light variable winds at all elevations. No significant precipitation expected.Friday: Freezing level starting at valley bottom, rising to about 1700m throughout the day. Mostly clear skies. Light SW winds at treeline, moderate W/SW winds at ridgetop.

Avalanche Summary

A few large avalanches were reported on Monday. Our field team was in the Crown Mountain area where they noticed a large slab avalanche on an extreme E/NE face that was likely triggered by cornice fall. In the neighboring Waterton region cornice failure resulted in 2 large avalanches that stepped down to the mid-February interface on NE facing features at 2400m. On Saturday in the neighboring Lizard Range a size 2.5 avalanche that was also likely triggered by cornice fall was observed.

Snowpack Summary

Monday night brought the first good overnight refreeze in recent memory which likely resulted in a short lived surface crust. A few good overnight re-freezes could really help the currently sloppy snowpack. The snowpack is reportedly isothermal as high as 2000m at this point and even the highest elevations are probably not far off. The mid-March rain crust is down 35 to 70cm and has shown a good bond with snow above. Old persistent weak layers are still intact in the mid and lower snowpack and there may be potential for these layers to wake up with a large cornice fall, sustained warming and or a significant rain event. Recent conditions have been favorable for cornice growth, large and vulnerable cornices hang precariously in the balance over many alpine features.

Problems

Wind Slabs

Recent upper elevation winds out of the southwest/west may have formed fresh and potentially touchy wind slabs. These are likely most problematic in terrain immediately lee of ridge-crest.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.>Travel on ridgetops to avoid wind slabs on slopes below, but be careful with cornices!>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Cornices

Many ridge-lines are wearing visor like cornices. These large, vulnerable and dangerously heavy chunks of snow hang precariously over many alpine features. Cornice failure has recently triggered large avalanches running on the mid-Feb PWL.

Give cornices a wide berth when traveling on or below ridges. Remember that cornices become weak with daytime heating.>Conditions are greatly improved, but be mindful that deep instabilities are still present.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Apr 1st, 2015 2:00PM