Avalanche Forecast

Issued: Mar 11th, 2016 9:10AM

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

jlammers, Avalanche Canada

Cariboos.

Watch for new wind slab development on Saturday. Forecast snowfall amounts are uncertain, so pay close attention to how much snow falls in your area, and choose terrain accordingly.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Saturday

Weather Forecast

Up to 12cm of new snow is expected on Saturday, although snowfall amounts are tough to pin down due to the convective nature of the weather pattern. Light flurries and a mix of sun and cloud are forecast for Sunday and Monday. Ridgetop winds should be moderate from the south on Saturday, and then become light for the rest of the forecast period. Freezing levels should sit at about 1800m on Saturday, and the drop to 1500m for Sunday and Monday.

Avalanche Summary

A widespread round of wind slab avalanche activity to size 2 was observed in response to new snow and strong winds on Thursday. At the time of publishing there were no new reports of avalanche activity on Friday, although solar radiation may have triggered a round of loose wet avalanches in steep, sun-exposed terrain.

Snowpack Summary

Snowfall accumulations on Thursday were in the 10-20cm range. Strong southerly winds redistributed these accumulations into touchy wind slabs at treeline and in the alpine. At elevations above around 1600 m, approximately 50-80 cm snow rests above a prominent weak layer buried on or around February 27. This weak layer comprises surface hoar sitting on a crust and is reported to be most prominent at sheltered treeline elevations. A couple of sun crusts might exist in the upper 50-70cm on southerly aspects.

Problems

Wind Slabs

New snow and wind will form new wind slabs in upper elevation lee terrain. The new snow may also be hiding older, larger wind slabs which formed on Thursday.

Be cautious as you transition into wind affected terrain.>The recent snow may now be hiding windslabs that were easily visible before the snow fell.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

A crust/surface hoar layer buried approximately 70 cm below the surface is triggerable by people on sleds or on skis. This layer has the potential to produce large avalanches and should be treated with respect.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Cornices

Large cornices loom over open bowls and alpine faces. Not only are massive cornice falls a hazard in themselves, but they can also act as a heavy trigger for slab avalanches on the slope below.

Give cornices a wide berth when travelling on or below ridges.>Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Mar 12th, 2016 2:00PM