Avalanche Forecast

Issued: Mar 18th, 2014 8:37AM

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

Wednesday: Periods of snow â€“ 10-15 cm. The freezing level is near 1000-1200 m and ridge winds are moderate from the W-SW. Thursday: Cloudy with flurries and sunny breaks. The freezing level is around 800 m and ridge winds are light from the NW. Friday: A mix of sun and cloud. The freezing level is around 800 m and ridge winds are light from the NW.

Avalanche Summary

Gusty northwest winds appeared to trigger a few fresh wind slabs from steep lee slopes on Monday. There was also a report of a size 3 natural slab avalanche from a steep south aspect that released on the Feb. 10 layer. This slide occurred during a brief sunny break and sympathetically triggered another size 2.5 on a nearby slope. 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

Periods of strong westerly winds have created fresh wind slabs in exposed lee and cross-loaded terrain. Around 40-60 cm of recent storm snow sits on a crust in most places, which may also be mixed in with surface hoar in some areas. Weaknesses have been observed within the storm snow and at the interface with this layer. The early March weak layer, 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 deep and is widespread throughout the region. Heavy triggers like a surface avalanche in motion or a cornice fall 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

More snow is forecast for Wednesday, adding to the 30-60 cm of recent storm snow. This new snow is sitting on a layer of surface hoar and/or a sun crust and may not be bonding well. Expect dense wind slabs in exposed lee terrain.

Be cautious as you transition into wind affected terrain.>Choose well supported terrain without convexities.>

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.

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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Mar 19th, 2014 2:00PM