Avalanche Forecast

Issued: Jan 3rd, 2014 9:18AM

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

slemieux, Avalanche Canada

South Rockies.

Conditions are complex. Choosing conservative terrain during the sunny weekend is your best bet.

Summary

Confidence

Fair - Due to the number and quality of field observations

Weather Forecast

Tonight and Saturday: Cold front has passed through the region, leaving behind a colder NW flow with lingering moderate snowfall amounts for tonight. Expect moderate to strong NW winds with freezing level at valley bottom and temperatures around -12 C at 1500 m. Sky should be partly cloudy on Saturday.Sunday: The ridge of high pressure keeps dominating the weather pattern keeping freezing levels low, moderate winds from the NW and partly cloudy skies. Monday: Light amounts of snow is possible as an upper disturbance cross over the region.

Avalanche Summary

Poor visibility resulted in limited terrain observation. We expect some avalanche activities happened and might still be happening with loading of new snow.

Snowpack Summary

Around 45 cm of new snow fell over the region with moderate W-SW winds creating touchy storm slabs and wind slabs on leeward alpine and top of treeline elevation band. Loading will continue on E-SE slopes on Saturday as winds keep blowing during the day tomorrow from the NW. Natural avalanche activity is still possible on leeward slopes in the alpine and top of treeline because of the storm snow available for transport. The storm snow interface has produced moderate snowpack test results and deeper surface hoar weak layers have produced hard test results. The persistent weak layers of surface hoar and facet/crust down 80-100 cm are a concern to avalanche professionals since triggering a fresh windslab or stormslab could step down to these layers and create bigger problems. Areas with shallower snowpack and rocky/planar slopes have also been reported as weak due to basal facetting (sugary, non-supportive snow at the bottom of the snowpack).

Problems

Storm Slabs

Windslabs are expected to keep forming on leeward slopes which could lead to natural avalanches. The storm snow in more sheltered areas will still need some time to settle and could be still touchy.

Space out and travel quickly through runout zones of avalanche paths.>Choose conservative lines and watch for clues of instability.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 5

Persistent Slabs

An avalanche triggered in the new snow or new windslab could step down to a persistent weakness in the snowpack buried down 100 cm.

Dig down to find and test weak layers before committing to a line.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 6

Valid until: Jan 4th, 2014 2:00PM