Avalanche Forecast

Issued: Mar 17th, 2014 8:41AM

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

Peter, Avalanche Canada

South Columbia.

Summary

Confidence

Fair

Weather Forecast

Tuesday: Mainly cloudy with a chance of flurries â€“ around 5 cm. The freezing level is around 1500 m. Ridge winds are moderate from the W-SW. Wednesday: Periods of snow â€“ 10-20 cm. The freezing level is near 1300 m and ridge winds are moderate from the West. Thursday: Cloudy with flurries and sunny breaks. The freezing level is around 1000 m and ridge winds are light.

Avalanche Summary

On Sunday a few small natural avalanches were reported in steep alpine terrain. Skier and explosive control work also produced numerous size 1-2 soft slabs, primarily from wind loaded slopes at or above treeline. On Friday there was also a report of a size two avalanche that was triggered accidently on a North facing slope at treeline on the early March surface hoar/crust combo. Last Saturday's avalanche fatality occurred in the Keefer Lake area northeast of Cherryville. The avalanche, which occurred in a cut block at about 1700m, involved 3 sledders who were in a party of 6. Two of the men were able to inflate their airbags and were partially buried. The deceased was reportedly not able to inflate his airbag, and was buried approximately 5m below the surface

Snowpack Summary

Another 10-15 cm of new snow brings the total recent storm snow total to 40-60 cm. Periods of strong westerly winds have created fresh wind slabs in exposed lee and cross-loaded terrain. The new snow sits on a crust in most places, which may also be mixed in with surface hoar in some areas. The early March interface, which is primarily surface hoar in sheltered areas and a sun crust on solar aspects, is now down 90-120 cm. The February 10th surface hoar/facet/crust combo is 120cm - 200cm below the snow surface and widespread throughout the region. Surface avalanches in motion and cornice fall still have the potential to initiate an avalanche on this deeply buried weak layer. An avalanche releasing on one of the deeper persistent weak layers would be very large and dangerous!

Problems

Storm Slabs

Weaknesses may still exist within or under the recent storm snow. Also, expect fresh dense wind slabs on exposed lee slopes and in cross-loaded terrain features.

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: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The early March sun crust/surface hoar combo should not be underestimated. While there's a lot of uncertainty and complexity surrounding this layer, it's important to note that human triggering is most likely at treeline.

The trees are not the safe-haven they normally are at this time. Terrain at treeline is primed for human triggered avalanches. >Use conservative route selection, stick to moderate angled terrain with low consequence.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Deep Persistent Slabs

The early February Persistent Weak Layer is still active and has produced some stunning avalanches recently. Very large avalanches may result from a surface avalanche in motion, a cornice fall or a rider finding the sweet spot.

Be aware of the potential for large, deep avalanches due to the presence of deeply buried weak layers.>Avoid rock outcroppings, large convexities and anywhere the snowpack is thin and/or variable.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Mar 18th, 2014 2:00PM