Avalanche Forecast Purcells

Date Issued: Valid Until:

Avalanche Canada kdevine, Avalanche Canada

Avalanche Forecast

Sat Mar. 9th ยท 4:50PM

Alpine

Danger Ratings Low

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 Moderate

Treeline

Danger Ratings Low

Below Treeline

Danger Ratings Low
Low hazard doesn't mean no hazard! Watch for isolated pockets of wind slab at upper elevations and loose snow sloughing - especially on sun exposed slopes.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Tuesday

Weather Forecast

SATURDAY NIGHT - Clear periods / light northwest wind / alpine low temperature near -13SUNDAY - A mix of sun and cloud / light northwest, switching to light southwest winds / alpine high temperature near -8 / freezing level 1200 mMONDAY - Mainly cloudy with isolated flurries / southwest winds 20-40 km/h / alpine high temperature near -7 / freezing level 1400 mTUESDAY - Flurries, 5-10 cm / light southwest winds / alpine high temperature near -8 / freezing level 1100 m

Avalanche Summary

On Friday, there were reports of several natural and explosives triggered avalanches to size 2.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.

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, large open glades and south facing slopes.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 - Unlikely

Expected Size

1 - 1.5