Purcells

Numerous, large persistent slab avalanches were reported in the northern portion of this region last week.

Avoid steep, convex terrain and rocky areas where triggering is more likely.

There have been numerous natural and skier triggered very large(up to size 3) persistent slab avalanches reported on all aspects at treeline and above in the Esplanade range over the past week. They have been failing on a weak layer of surface hoar down 50-70 cm.

This weak layer is a concern throughout much of the region.

Numerous explosive triggered wind slab avalanches up to size 2.5 were reported on primarily northeasterly aspects in the alpine on Sunday.

5-15 cm of recent snow and strong west wind formed wind slabs on lee features at treeline and above.

The primary layer of concern in much of this region is a weak layer of surface hoar down 50-70 cm. This layer may be less likely to trigger in areas that have a strong, supportive crust above.

In the southern portion of the region, weak facets near the ground may be the primary layer of concern. Especially in shallow, rocky areas in the alpine.

Average snowpack depths at treeline are 70-120 cm which tapers rapidly below treeline.

Monday Night

Partly cloudy skies, southwest alpine wind 20 km/h, treeline temperature -12 °C.

Tuesday

Mix of sun and cloud, southwest alpine wind 30 km/h, treeline temperature -7 °C.

Wednesday

Mostly sunny skies, south alpine wind 30 km/h, treeline temperature -7 °C.

Thursday

Mix of sun and cloud, southwest alpine wind 30 km/h, treeline temperature -6 °C.

More details can be found in the Mountain Weather Forecast.

• Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
• Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
• Surface hoar distribution is highly variable. Avoid generalizing your observations.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.