Avalanche Forecast Purcells

Date Issued: Valid Until:

Avalanche Canada jsmith, Avalanche Canada

Avalanche Forecast

Fri Apr. 12th ยท 5:06PM

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Moderate

Below Treeline

Danger Ratings Low
Wind Slabs Wind Slabs

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Moderate

Below Treeline

Danger Ratings Low

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low
Lingering wind slabs may still be reactive to human triggers; especially in lee features below ridgetops.

Confidence

High -

Weather Forecast

FRIDAY NIGHT: Partly cloudy / Light, westerly winds / Alpine low -4 C / Freezing level 1300 m.SATURDAY: Cloudy with flurries; 2-5 cm. / Moderate, southwesterly winds / Alpine high -2 C / Freezing level 1800 m.SUNDAY: Mostly cloudy / Light, westerly winds / Alpine high -4 C / Freezing level 1600 m.MONDAY: Mix of sun and cloud / Light, southwesterly winds / Alpine high -3 C / Freezing level 1600 m.

Avalanche Summary

No new avalanches were reported in this region on Thursday.On Tuesday, skiers were able to trigger slabs up to size 1.5 in steep, gully features as low as 2200m. Explosives produced avalanches to size 2 and a helicopter remotely triggered a size 1.5 avalanche from 200 m away. They initiated in steep, alpine terrain above 2400 m, mostly on northerly aspects.On Sunday, small (size 1-1.5) wind slabs were reactive to skiers, generally around ridge crests and steep, convex terrain above 2200 m. The most reactive deposits were in immediate lee features, including a size 2 wind slab avalanche remotely triggered from a rocky saddle 10 m away.

Snowpack Summary

Currently, the snowpack structure changes dramatically with elevation and aspect. 5-25 cm. of recent storm snow (amounts tapering with elevation) is sitting on a melt/freeze crust, except for north facing terrain above 2100 m. where the old snow surface remained dry and small surface hoar (weak, feathery crystals) may be present in isolated locations. This recent snow has been affected by the sun and re-distributed by southwesterly winds, forming wind slabs on lee features below ridgetops.Weak facets (sugary grains) remain at the bottom of the snowpack in the alpine creating a low likelihood, high consequence scenario that would likely require a large trigger to initiate an avalanche. Steep, rocky areas with a shallow or highly variable snowpack are the most likely places to trigger a very large avalanche on this layer.Below roughly 1900 m, the snowpack is moist and is melting rapidly at lower elevations. Check out this useful link for managing avalanche hazard during spring conditions HERE.

Problems

Wind Slabs

Wind Slabs

Recent snow has formed slabs in the alpine and alpine features around treeline. Use caution around ridge crests, lee terrain features and steep, convex slopes.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Pay attention to changing conditions with elevation/aspect.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2