Purcells

At upper elevations, where the dry snow sits on a crust, persistent slabs have been propagating widely, are surprisingly deep, and could be triggered by warmth, cornices, or riders.

Remain cognizant that a weak, unpredictable layer continues to lurk near the bottom of the snowpack, avoid thin, rocky start zones and shallow areas with variable snowpack depths.

Check for signs of windslab avalanche danger like shooting cracks, especially near ridgetops and in cross loaded gullies.

On Sunday, small natural loose wet avalanche activity was reported on slopes impacted by the afternoon sun.

On Saturday, a widespread natural slab avalanche cycle was observed and reported. These avalanches were very large up to (size 3) and are suspected to be storm snow than ran on a crust buried in early April.

A fatal avalanche occurred on April 15 in the Thunderwater Lake riding area, just west of this region. The avalanche was triggered near a rocky area and was very large (size 3). Two riders were caught, one was buried approximately 2 meters deep. Despite an immediate extrication rescue response, the rider did not survive. Any additional information we have on this accident can be found in this MIN.

If you are getting out in the backcountry, consider making a post on the MIN (Mountain Information Network). You can share riding conditions, avalanche or snowpack observations, or even just a photo or two.

At treeline and above, 15-40 cm of recent snow fell with moderate to strong southwest wind, forming windslabs in leeward terrain and storm slabs. A variety of crust, surface hoar and/or facet layers that were buried in mid March through early April may exist in the upper snowpack. Recent avalanche activity in adjacent regions indicate that these interfaces contributed to the current avalanche problem there. Most professional operations in the forecast area are tracking their own local layer of concern to see if they become active with increasing temperatures, or more load from new rain or snow.

Below treeline, expect to find moist or refrozen surfaces, and shrinking snowpack depths.

The mid snowpack is generally settled and strong, although west of Invermere, some professional operations are still monitoring a layer of weak, feathery surface hoar crystals that was buried in mid January.

The lower snowpack includes a widespread layer of large, weak facets and/or depth hoar crystals. This weak layer has been responsible for several very large and destructive avalanches throughout the season, including one last Thursday.

Monday Night

Mostly clear. Light, gusting moderate, southeast ridgetop wind. Freezing levels remain around 1300 m. Treeline low around -5 °C.

Tuesday

Partly cloudy with scattered flurries beginning late afternoon flurries, 5 - 10 cm accumulation. Light southeast ridgetop wind switch to west in the afternoon. Freezing levels rise to 1700 m. Treeline high around 0 °C.

Wednesday

Cloudy with sunny periods and isolated flurries, trace accumulation. Light northwest ridgetop wind. Freezing levels rise to 1600 m. Treeline high around -1 °C.

Thursday

Mix of sun and cloud. Light northwest ridgetop wind. Freezing levels rise to 1900 m. Treeline high around 0 °C.

More details can be found in the Mountain Weather Forecast.

• Be especially cautious as you transition into wind affected terrain.
• Be alert to conditions that change with aspect and elevation.
• Watch for unstable snow on specific terrain features, especially when the snow is moist or wet.
• Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.