Avalanche Forecast

Issued: Feb 28th, 2016 7:11AM

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

pmarshall, Avalanche Canada

South Columbia.

New snow may not bond well to the older snow surface, especially in wind-loaded terrain. Choose your lines carefully and avoid exposure to terrain traps.

Summary

Confidence

High

Weather Forecast

Monday: Up to 15 cm overnight then cloudy with sunny breaks and a chance of flurries. The freezing level rises to around 1400 m during the day. Ridge winds are moderate or strong from the W-NW, easing to light during the day. Tuesday: Cloudy with periods of snow 5-10 cm. The freezing level is near 1400 m and winds are moderate to strong from the SW. Wednesday: Cloudy with flurries and sunny breaks. The freezing level rises to 1600 m and ridge winds are light.

Avalanche Summary

Numerous natural and rider triggered wind slab avalanches were reported on Saturday. These thin slabs occurred on a variety of aspects in wind-loaded terrain and were generally 15-20 cm deep. There were also reports of loose snow sluffing on steep north (dry snow) and south (wet snow) facing slopes. There was also a report of a small wind slab that initiated in steep terrain, ran off a cliff, and triggered a size 3 persistent slab on the slope below. This event occurred on a north facing alpine slope.

Snowpack Summary

25-40 cm of new storm snow sits on a crust on solar aspects and lower elevation terrain, and surface hoar on shady and sheltered slopes. Touchy new wind slabs are likely in exposed lee terrain at and above treeline. A weak layer of surface hoar and/or a sun crust buried February 21 is now 40-70cm below the surface. Where it exists, this layer may become reactive to human triggers as the overlying slab develops. The surface hoar and/or crust layer buried February 10 is now down 75-120cm. This layer was less reactive over the weekend with cooler temperatures, but remains a concern for large triggers like cornice falls or a smaller slide in motion. Cornices are large and potentially weak and should be avoided if possible.

Problems

Storm Slabs

Fresh storm slabs are developing and overlie a crust and/or recently buried surface hoar. Triggering these fresh soft slabs is more likely in steep terrain that has been loaded by NW-SW winds.

Avoid freshly wind loaded features.>Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Persistent Slabs

Smaller sluffs or storm 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 80 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.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

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