Avalanche Forecast Purcells

Date Issued: Valid Until:

Avalanche Canada jsmith, Avalanche Canada

Avalanche Forecast

Fri Mar. 15th ยท 4:57PM

Alpine

Danger Ratings Moderate

Treeline

Danger Ratings Moderate

Below Treeline

Danger Ratings Moderate
Persistent Slabs Persistent Slabs
Loose Wet Loose Wet

Alpine

Danger Ratings Considerable

Treeline

Danger Ratings Considerable

Below Treeline

Danger Ratings Moderate

Alpine

Danger Ratings Considerable

Treeline

Danger Ratings Considerable

Below Treeline

Danger Ratings Considerable
Warming temperatures have settled the recent storm snow into a cohesive slab sitting on weak facets (sugary snow) that is ripe for human triggers; intense solar radiation will increase the likelihood of human triggered avalanches.

Confidence

Moderate -

Weather Forecast

FRIDAY NIGHT: Partly cloudy / Light, westerly winds / Alpine low -10 / Freezing level below valley bottom.SATURDAY: Partly cloudy in morning becoming mostly sunny / Light, westerly winds / Alpine high 2 / Freezing level rising to 1800 m.SUNDAY: Sunny / Light, northwesterly winds / Alpine high 5 / Freezing level rising to 2200 m.MONDAY: Sunny / Light, northwesterly winds / Alpine high 7 / Freezing level rapidly rising to 2500 m.

Avalanche Summary

On Thursday, several rider triggered persistent slab avalanches up to size 2 were reported on a variety of aspects at treeline elevations. Human triggering of these persistent slabs is expected to increase with the forecast sunshine and warming.On Wednesday, numerous naturally triggered wind slab avalanches up to size 2.5 and a few human triggered wind slabs up to size 1.5, were reported primarily on easterly aspects at treeline and above.

Snowpack Summary

15-30 cm of recent storm snow is sitting on a pile of facets (sugary snow), as well as a crust on sun exposed slopes. The recent storm snow has settled into a cohesive slab and is ripe for human triggering. This persistent slab is currently our primary concern.At lower elevations, a weak layer of surface hoar (weak, feathery crystals) buried in mid-January can be found approximately 50-90 cm deep. This layer has recently been unreactive, however, the forecast warming event may awaken this layer in low elevation areas such as steep cutblocks and large open glades.The base of the snowpack is composed of facets (weak, sugary snow) that sit on a crust. Large avalanches failing on these facets may become more likely after a long period of warming.

Problems

Persistent Slabs

Persistent Slabs

Warming temperatures have settled the recent storm snow into a cohesive slab sitting on weak facets (sugary snow) that is ripe for human triggers; especially at treeline and above.

Avoid convex slopes on rocky terrain with a variable snow depth.Use extra caution on solar aspects where the new snow is sitting on a crust.Avoid steep terrain where the snow feels moist or slabby.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Possible

Expected Size

1.5 - 2.5
Loose Wet

Loose Wet

Pin-wheeling snow below cliffs is a common sign that loose wet avalanches are becoming more likely.

Reduce exposure to over-head hazards such a large cornices during periods of strong solar radiation.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Avoid steep, sun exposed slopes when the solar radiation is strong.

Aspects: East, South East, South, South West, West.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 1.5