Avalanche Forecast

Issued: Mar 14th, 2013 10:47AM

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

Cariboos.

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 westerly / Freezing level dropping from 1800m to 1200mSaturday: Light snowfall / Moderate west winds / Freezing level at 1200mSunday: Light snowfall / Light northwest winds / Freezing level at surface

Avalanche Summary

Several natural storm slab avalanches to size 2.5 were reported from the region on Wednesday. They occurred on various aspects and elevations. At least 1 of the reported avalanches failed on the recently buried surface hoar. That avalanche was on a north aspect at 1900m and had a crown of 60-100cm. I would expect fairly limited observations with reduced visibility on Thursday.

Snowpack Summary

Strong Southwest winds, new snow, and warming temperatures are contributing to an ongoing storm slab problem. The new storm snow overlies a widespread layer of surface hoar that developed during the recent clear weather. Sun crusts also developed during the clear weather on solar aspects up to about 2000 metres. Some areas had strong winds before the surface hoar was buried, so its distribution may be specific to sheltered and shaded terrain features. There is still concern for the buried weak layer of surface hoar from February 12th that is now down more than a metre in most places. The forecast new load of snow and wind may overload this deeply buried weak layer in areas that did not slide after the last storm.

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.

Be alert to conditions that change with elevation.>The new snow will likely require several days to settle and stabilize.>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 surface hoar buried down about 100-150 cm (February 12th layer) may be triggered by the new load of storm snow or by avalanches in motion.

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

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

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