Avalanche Forecast Purcells

Date Issued: Valid Until:

Avalanche Canada kdevine, Avalanche Canada

Avalanche Forecast

Fri Mar. 8th ยท 4:27PM

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low
Wind Slabs Wind Slabs

Alpine

Danger Ratings Low

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low

Alpine

Danger Ratings Low

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low
Wind slabs are likely to be encountered at upper elevations and may be reactive to human triggering, especially in lee features.

Confidence

Moderate -

Weather Forecast

FRIDAY NIGHT - Mainly cloudy with clear periods / west winds, 10 km/h / alpine low temperature near -13SATURDAY - Cloudy with sunny periods / northwest winds 10 km/h / alpine high temperature near -10SUNDAY - Mainly sunny / northwest winds 10-15 km/h / alpine high temperature near -9MONDAY - Flurries, 5 cm / southwest winds 20-40 km/h / alpine high temperature near -7

Avalanche Summary

On Wednesday and Thursday there were reports of several size 1 loose snow avalanches from steep terrain.On Tuesday, there were two reports of human triggered persistent slab avalanches that failed on the early February persistent weak layer (described in more detail in the Snowpack Summary). These were size 1 and 1.5, on west aspects.Reports of persistent slab avalanches are becoming less frequent, suggesting the January/February weak layers have evolved into a lower likelihood/high consequence avalanche problem.

Snowpack Summary

5-10 cm of recent storm snow is sitting mainly on wind slabs and facets (sugary snow), as well as surface hoar (feathery crystals) in sheltered areas and a crust on sun exposed slopes. There are up to three layers of surface hoar that were buried in mid and late January, and early February. These layers are around 30 to 80 cm deep and are most prominent at lower elevations. The surface hoar may sit on a crust on south facing slopes. The most recent reported avalanches on these layers have been on the early February layer. These reports have been mainly from the western portion of the region, near the boundary with the South Columbia region. Avalanches on these layers are infrequent, however it may still be possible to trigger an avalanche on these layers in isolated areas such as steep cutblocks are large open glades.The base of the snowpack is composed of weak and sugary faceted grains that sit on a crust. This weak layer has produced large and destructive avalanches that are sporadic in nature and difficult to predict. See the Forecasters' Blog here for more information on this problem. Continued cold temperatures have been weakening the lower snowpack.

Problems

Wind Slabs

Wind Slabs

Wind slabs can be found on all aspects and may continue to be reactive due to the weak, faceted snow they sit on.

Exercise increased caution around freshly wind loaded pockets near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5