Avalanche Forecast

Issued: Feb 28th, 2016 7:07AM

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

pmarshall, Avalanche Canada

Purcells.

New snow may not bond well to the older snow surface, especially where it's blown into dense pockets of wind slab.

Summary

Confidence

High

Weather Forecast

Monday: Around 5 cm overnight then cloudy with sunny breaks and a chance of flurries. The freezing level rises to around 1500 m during the day. Ridge winds are moderate or strong from the W-NW, easing to light during the day. Tuesday: Increasing cloud with flurries developing. The freezing level jumps up to 1500 m and winds ease to light. Wednesday: Cloudy with sunny breaks and a chance of flurries. The freezing level is near 1600 m and winds are light.

Avalanche Summary

Recent avalanche activity has consisted mainly of loose wet sluffs on steep sun-exposed slopes during the day and natural or explosive-triggered cornice falls to size 2.5. On Saturday, explosive-triggered cornices did not release slabs below on north and east aspects in the alpine. Late last week there were a couple reports of failing cornices triggering slabs up to 60 cm deep on slopes below.

Snowpack Summary

A dusting 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. Expect thin new wind slabs in exposed terrain. The surface hoar and/or crust layer buried in mid-February is now down 40-75cm. This layer was less reactive over the weekend with cooler temperatures. Large weak cornices have recently been a concern 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

Thin 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.

Be cautious as you transition into wind affected terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

Smaller sluffs or wind slabs, cornice falls, or a ride/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.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Caution around convexities or areas with a thin or variable snowpack.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Feb 29th, 2016 2:00PM