Purcells

Lingering wind slabs may remain reactive on steep, convex slopes below alpine ridgetops. A persistent slab problem may still be possible to trigger in isolated areas in the north of the region and warrants continued consideration.

 TUESDAY NIGHT: Increasing cloudiness / Moderate, west ridgetop wind / alpine low temperature -12 / Freezing level valley bottom.

WEDNESDAY: Cloudy with flurries; 2-5 cm. / Light, southwest ridgetop wind / alpine high temperature -5 / Freezing level 1300 m.

THURSDAY: Sunny / Moderate, northwest ridgetop wind / alpine high temperature -4 / Freezing level 1400 m.

FRIDAY: Sunny / Moderate, northwest ridgetop wind / alpine high temperature -1 / Freezing level 1700 m.

There was a MIN report on Monday of a small wet loose point release triggering a size 2 slab avalanche around 30 cm. deep on a south aspect. See MIN HERE.

Last week there were several notable reports of large human triggered persistent slab avalanches in the Dogtooth Range and Quartz Creek area. See these MIN reports here and here. The likelihood of triggering on these layers has since gone down, but it's still worth considering the potential for a similar release to occur.

Dry soft snow can be found on shaded aspects above around 1500 m. On south-facing slopes and at lower elevations expect crusty snow in the morning and soft moist snow in the afternoon. Recent wind slabs and cornices still pose a hazard close to steep ridgelines.

Persistent weak layers were reactive last week, particularly in the northern end of the Purcells. The layers of concern are a buried layer of surface hoar that formed in late January is 30-60 cm deep and an older surface hoar layer is 50-100 cm deep at treeline. These layers may exist as a combination of facets and crusts at other elevations. Recent assessments indicate the chance of triggering these layers has reduced, but writing them off completely is probably premature.

Shallow rocky areas where the snowpack is thin likely have sugary facets acting as a weak layer at the base of the snowpack.

• Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.
• Be aware of the potential for large avalanches due to the presence of a persistent slab.
• Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
• Caution around slopes that are exposed to cornices overhead.