The threat of wind slabs will increase at higher elevations through the day from strengthening winds. Noteworthy blowing snow will alert you to changing conditions. Although unlikely, there is lingering potential to trigger a high-consequence avalanche in terrain with shallow and variable snow depths. Terrain with a snowpack deeper than 5 feet and sheltered from the wind offers the safest riding today.
A fresh round of wind slabs will develop today or this evening with increasing northwest winds. Blowing snow will signal that shallow wind slabs are forming below ridges, in concave gullies, or below rollovers. Stay alert for small but sensitive drifts if you are riding in consequential terrain above cliffs, gullies, or trees.
2/6: A skier triggered wind slab on a leeward slope on Mt. Emmons.
In the Southeast Mountains, weak layers near the ground are buried 2 to 6 feet deep and have become a rare but consequential instability. Slabs are most easily triggered where they are thinner. Be cautious of wind-affected terrain with variable depths, rock bands, and snow-deprived areas where slabs are only a few feet thick. The safest riding is where the snowpack is uniform and consistently deeper than about 5 feet (150 cm), or on southerly aspects where recent warmups have strengthened the upper snowpack.
2/1: A large skier triggered persistent slab that failed on depth hoar at the ground near Park Cone.
Observations yesterday suggest that wind slab formation from Sunday night's system is fairly limited and becoming stubborn to triggers. In most terrain early this morning, you'll find 2" to 8" of soft, wind-protected powder. The soft powder on the surface, which is most abundant in the Northwest Mountains, is easily transportable by increasing west-to-northwest winds over the next 12 hours. Once winds reach sufficient speeds to mix into the terrain holding wind protected snow, they'll start drifting it into fresh wind slabs. This could happen today in some terrain, and will likely expand to more terrain after sunset as stronger winds accompany this evening's cold front. You can identify changing conditions by watching for blowing snow in your travels. This will be a relatively small and easy-to-recognize instability.
In stark contrast to the small and easy-to-recognize wind slab problem, persistent slabs remain a low-likelihood but high-consequence threat in the shallower parts of the Southeast Mountains. If you are riding in terrain where snow depths average less than about 5 feet (150 cm), take the time to assess the snowpack structure before riding in steep terrain. Evidence of the lingering problem comes from a close call last Wednesday, just outside of our forecast area on Park Cone, and unstable pit results over the weekend on a shallow, windward slope near treeline by Gothic. As we continue to distance ourselves from the last major loading event, which ended on January 31st, the threat of avalanches breaking on buried depth hoar layers continues to gradually diminish.
