Avalanche Forecast

Issued: Feb 29th, 2016 3:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

pmarshall, Avalanche Canada

Purcells.

Snowfall amounts could vary throughout the region on Tuesday. Regardless, expect touchy fresh slabs to develop. The size and likelihood will be greater where there is more than 20 cm of new snow with wind.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Tuesday: Periods of snow 5-10 cm. The freezing level is near 1400 m and winds are moderate to strong from the SW. Wednesday: Another 5-10 cm of snow should accumulate before tapering off throughout the day. The freezing level is near 1400-1600 m and ridge winds ease from moderate westerly to light. Thursday: Cloudy with flurries. The freezing level remains near 1400-1600 m and wind increase to moderate from the SW.

Avalanche Summary

No new avalanches were observed on Sunday. You will likely find fresh touchy wind slabs in lee and cross-loaded terrain. These wind slabs should increase in size and likelihood throughout the week with continued light snow and moderate ridge winds. Late last week there were a couple reports of failing cornices triggering persistent slabs up to 60 cm deep on slopes below.

Snowpack Summary

5-15 cm of new snow overlies a melt-freeze crust on solar aspects and lower elevation terrain, and might be covering a layer of surface hoar on shady and sheltered slopes at treeline and in the alpine. Fresh wind slabs are likely in exposed lee and cross-loaded terrain. The surface hoar and/or crust layer buried in mid-February is now down 40-70cm. This layer was less reactive over the weekend with cooler temperatures. Large weak cornices remain concerning and have recently triggered persistent slabs on slopes below. The early January surface hoar/facet layer is typically down 70-120cm. Triggering an avalanche on this layer has become unlikely but it still has isolated potential to produce very large avalanches with a heavy trigger. In general, the lower snowpack is well settled and strong, apart from some thin snowpack areas where basal facets exist.

Problems

Wind Slabs

Fresh wind slabs are likely in exposed terrain and may be touchy where they're sitting on a crust or recently buried surface hoar layer.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

Smaller sluffs or slabs, cornice falls, or a rider/group of riders in the wrong spot may be enough load to trigger a crust and/or surface hoar layer that is buried an average of 60 cm deep.

Caution around convexities or areas with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Mar 1st, 2016 2:00PM