Avalanche Forecast

SATURDAY NIGHT: Cloudy with isolated flurries. Light southwest winds.

SUNDAY: Cloudy with scattered flurries bringing about 5 cm of new snow, continuing overnight. Light to moderate southwest winds, becoming strong in the alpine. Alpine high temperatures around -6 with freezing levels to 1400 metres.

MONDAY: Mainly sunny. Light variable winds. Alpine high temperatures around -6 with freezing levels to 1500 metres.

TUESDAY: A mix of sun and cloud. Light variable winds shifting west. Alpine high temperatures around -6 with freezing levels to 1500 metres.

Warm sunny weather between Wednesday and Friday resulted in a widespread cycle of wet loose avalanches on sun-exposed slopes. Photos from this flight over the southwestern Purcells shows so some very large wet avalanches that ran to valley bottom. Cooling temperatures have since worked to stabilize this problem.

Over the past week there have been several notable reports of large human triggered persistent slab avalanches in the Dogtooth Range and Quartz Creek area, including:

• A remotely triggered size 2 avalanche on Tuesday on a northwest slope at 2100 m that failed on a 40 cm deep weak layer (MIN report)
• A size 3 human-triggered avalanche on Feb 27 on a east-facing alpine slope (MIN report)
• A size 2 avalanche on Feb 27 on a south-facing slope (MIN report)
• A few remotely triggered size 2 avalanches on Feb 24 (MIN report)

While in most parts of the Purcells the main concern over the weekend is wind slabs (both old and new), backcountry travelers in the northern tip of the region should be extra cautious about the lingering persistent slab problem in this area.

5-15 cm of new snow over Friday night accumulated above moist and crusty interfaces that formed during the recent warm up. Some deeper accumulations can be expected in lee terrain features. High shaded terrain will have a mix of soft snow and some old buried wind slabs. 

Persistent weak layers have been most active in the northern end of the Purcells where a buried layer of surface hoar that formed in late January is 40-80 cm deep and an older surface hoar layer is 60-120 cm deep at treeline. These layers may exist as a combination of facets and crusts at other elevations. Recent observations suggest these layers have been less problematic as you move further south.

Steep rocky areas where the snowpack is thin likely have additional weak layers near the base of the snowpack.

• If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.
• Be carefull around freshly wind loaded features.
• Caution around convexities or sharp changes in terrain.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.