Dangerous avalanche conditions exist at higher elevations. Avoid wind slabs on upper slopes on all aspects. The latest storm snow is resting atop a fragile and faceted base, prevalent across all aspects and elevations. Today's travel advise is to ski and ride on slopes with gradients less than 30 degrees, and avoiding those below or next to avalanche runout zones.
Winds have been shifting directions all over the compass, and creating wind slabs at tree line and above on all aspects. Very cold temperatures have been keeping the most recent storm snow light and available for transport. Wind effect can be seen on all aspects, and cracking underfoot as well as density changes are key indicators of wind slab development.
Photo: Brian Hilland
Frigid temperatures have penetrated the snowpack over the last week. Our primary concern is the interface with the old snow from November and early December interacting with the new snow from the most recent storms. This layer lives about 2 feet below the surface. Facets developing on the old surface of the snowpack are contributing to the problem. The new snow has formed wind slabs which are unstable at high elevations on leeward slopes. We have uncertainty about how well the old snowpack is bonding . While out checking conditions, we aren't experiencing the typical 'Red flags' or poor test scores that would normally lead us to concern, but the interaction between the old and new snow feels like a sleeping giant. As new snow settles and becomes firmer, forming a slab, it may become more reactive.
The snowpack at upper elevations is potentially dangerous and can be challenging to navigate near and above treeline. Strong winds and large amounts of snow from recent storms have significantly increased the height of the snowpack which contributes to a more complex snowpack. Expect to find different depths and structure on different aspects and elevations. Snowmobiles and skiers are likely to trigger avalanches on wind slabs that live near defined ridgelines. Those avalanches could have significant consequences, partiticularly on slopes with steep starting zones. Todays a day you may get away with a bad choice, or you may find that thin spot and trigger a big avalanche. Just because you "got away with it" doesn't mean it was a good decision. The sleeping giant is most likely hiding at upper elevations on steep, wind loaded slopes. I'd reccomend not waking it up!
If riding or out for a tour, mid-elevation treelines offer great snow. Plan to stay on lower angle terrain, and stear clear of avalanche runout areas.
A weather system with widespread snow will enter the region starting Tuesday night. NOAA's forecasting between 12 to 18 inches in the Selkirks and Cabinet Zone, accompanied by freezing temperatures. Expect Avalanche Danger to increase with the new storm.
