Avalanche Forecast

Issued: Jan 10th, 2016 7:35AM

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

Avalanche Canada jlammers, Avalanche Canada

Watch for reactive pockets of wind slab that may be sitting on a layer of recently buried surface hoar.

Summary

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

Clear skies and valley cloud are forecast for Monday as the dry ridge of high pressure holds on for one more day. On Tuesday a Pacific front will move inland bringing trace amounts of new snow on Tuesday night and up to 5cm on Wednesday. Ridgetop winds associated with the front will be strong and southwesterly. Freezing levels will hover around valley bottom on Monday and then rise to about 1300m with the passage of the front.

Avalanche Summary

Explosives control on Saturday triggered a size 1 wind slab in the south of the region. No other recent avalanches have been reported in the South Rockies region. Several avalanches were reported in the Lizard/Flathead region on Thursday and Friday. The primary problem in that region is wind slabs failing on the early January surface hoar layer. Similar conditions may exist in some parts of the South Rockies.

Snowpack Summary

The Avalanche Canada field team has been finding variable conditions across the region this week. Up to 10cm of recent snow has fallen burying a layer of surface hoar in sheltered features. In the east of the region the snow surface is now widely wind affected with thin but stiff wind slabs in lee features at treeline and in the alpine. In areas that have seen less wind (a good indicator would be snow still hanging on the trees), these wind slabs may be softer and deeper. In either case, snow pit tests in wind loaded features show these slabs are failing under moderate loads and can propagate over wide distances. The early December crust can be found down around 60cm. It is not currently expected to pose an avalanche problem but could wake-up in the future with substantial warming or heavy snow loading.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent tests suggest that wind slabs may be triggered by riders in the alpine and at treeline.  Watch out for hard slabs in heavily wind affected areas and deeper soft slabs sitting above surface hoar in more wind sheltered areas.
Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>Today is not the day to set the record highmark.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 11th, 2016 2:00PM