Avalanche Forecast

Issued: Mar 14th, 2013 10:41AM

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

jlammers, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Timing of incoming weather is uncertain on Friday

Weather Forecast

Overnight Thursday and Friday: Heavy precipitation becoming light on Friday / Moderate to strong southwest winds becoming moderate and westerly / Freezing level dropping from 1500m to 1200mSaturday: Light snowfall / Moderate west winds / Freezing level at 1200mSunday: Light snowfall / Light northwest winds / Freezing level at surface

Avalanche Summary

Natural storm slab avalanches to size 2.5 were reported yesterday. The occurred on a variety of aspects at treeline and above, and in some cases failed on the recently buried surface hoar.

Snowpack Summary

A deep and cohesive storm slab continues to develop at higher elevations while rain has saturated the snowpack in areas below treeline. The newly formed storm slab overlies a few older surfaces which include weak surface hoar on shaded aspects, and a sun crust on solar aspects. This interface was reported to be highly reactive in recent days with avalanches triggered from remote locations and propagating long distances. The weak layer of surface hoar buried on February 12th is now down about 100-150 cm. Some areas report that this layer is rounding and getting harder to shear in snow profile tests, but continues to give planar shears when it does fail. The new load of storm snow may cause another cycle of natural activity at this interface.

Problems

Storm Slabs

Touchy storm slab conditions will continue in the wake of heavy precipitation and strong wind, especially in wind-affected terrain or in areas where recently buried surface hoar exists.

The new snow will require several days to settle and stabilize.>Good day to make conservative terrain choices.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 6

Persistent Slabs

A weak layer of buried surface hoar down about 100-150 cm may be triggered by the load of new storm snow and wind.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

4 - 7

Valid until: Mar 15th, 2013 2:00PM