Purcells

Watch for small but touchy new wind slabs forming in the immediate lee of ridges and exposed terrain features. Monitor new snow amounts as you travel and be ready to manage a more widespread storm slab problem if you're in an area that sees more than 15 cm of new snow accumulate.

Wednesday night: Cloudy with scattered flurries bringing 5-10 cm of new snow. Light to moderate southwest winds.

Thursday: Cloudy with continuing scattered flurries bringing another 5-10 cm of new snow. Light to moderate south or southwest winds. Alpine high temperatures around -8.

Friday: Mainly cloudy. Light variable winds. Alpine high temperatures around -11.

Saturday: Mainly cloudy. Light to moderate southwest winds, increasing over the day and overnight. Alpine high temperatures around -12.

On Sunday in Glacier National Park, a skier triggered a size 2 avalanche upon entrance into a cross-loaded terrain feature.

We're continuing to track a layer of surface hoar from early January which is trending unreactive. Two MIN reports (MIN report 1; MIN report 2) from north of the region in Hope Creek report human-triggered slab activity from January 20. This MIN report from the Quartz zone (from Jan 14) shows a reactive layer of Jan 11th surface hoar on north-facing slopes near treeline. Investigate for this layer around sheltered treeline slopes where surface hoar has been preserved. 

Following the mid-January storm, we received reports of avalanches reaching size 3 in the central part of the region, lending support to the idea that some larger releases may have involved more deeply buried persistent weak layers. Check out this MIN report from Mt McKay. Although avalanche activity on these layers from early December and November has been isolated, the possibility exists for large triggers to reactivate these deeper instabilities. 

Light flurries have begun to bury a layer of surface hoar recently reported in sheltered areas of the region howver gusty winds over the weekend likely damaged these crystals in more exposed upper elevations. Aside from this weak surface crystal, the new snow is burying a variety of surfaces including scoured and pressed surfaces in exposed terrain as well as more variable wind affected and facetted snow in sheltered terrain. A thin sun crust may be found on steep solar aspects.

A weak of layer of surface hoar from Jan 11th is down 10-50cm. In recent snowpack tests this layer has produced sudden results at treeline elevations in areas near KHMR. This persistent weak layer is most suspect in sheltered, open slopes at treeline and warrants slope-specific investigation if you're travelling in the north of the region.

Two deeper layers of surface hoar from December 13th and December 7th may still be found down 100-150 cm. The Dec 7th weak layer consists of a combination of decomposing surface hoar with a crust and faceted snow. Avalanche activity on these persistent weak layers has dwindled in the last week, with snowpack tests results trending to resistant and unreactive. 

The lower snowpack is characterized by a notable rain crust from early November that is surrounded by a weak layer of sugary facets. It may still be possible to trigger with large loads in steep, shallow, rocky areas with a thin to thick snowpack.

• Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
• Storm slab size and sensitivity to triggering will likely increase through the day.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.