Dangerous avalanche conditions exist in the backcountry. Significant snowfall and strong southwest to west winds since early Tuesday morning have formed sensitive wind slabs at all elevations. These slabs will be larger and more sensitive above 8500 feet where the possibility also exists for the release of very large and destructive hard slabs that lie on a layer of weak faceted snow near the base of the snowpack. Predicting the release of a persistent slab is difficult and requires an evaluation of the snowpack to the ground and the best way to avoid an accident today is by simply making conservative route and terrain choices. Remember to consider the terrain above your route as it is possible for avalanches to run long distances today. At the low elevations, smaller avalanches could be triggered on very steep terrain features and terrain traps should be avoided.
New wind slabs have formed on leeward terrain. These slabs will be sensitive to backcountry riders and skiers today and could release naturally. These slabs will release as soft slabs and could have depths of one to three feet.
Rapid loading has increased the likelihood for the release of large to very large avalanches involving weak snow buried on December 5th. Such an event could be triggered when a single person hits a weak spot on a slope, by larger triggers such as groups or a snowmachine, or by the release of a wind slab. If triggered these slabs will be hard, have depths of three to six feet and are likely to have dire consequences for anyone involved.
( Discussion is generated from the previous day's afternoon forecast. )Another round of snow arrives on a northwest flow late tonight with sixteen to twenty inches possible in the next twenty-four hours for the Tetons and Salt River Ranges. Valley locations will also receive a good amount with twelve to fifteen inches possible in Star Valley and Jackson. The Togwotee area is forecast to receive eight to ten inches. West wind will average around twenty-five mile per hour with gusts to fifty on ridgelines in the Tetons with stronger winds to the south in the Salts. Expect wind speeds around thirty miles per hour there. Temperatures will rise slightly during this period from the single digits to the upper teens. Wind blown snow will add further stress to the weak layer deep in the snowpack while building slabs one to three feet in thickness. In places where the snowpack is thinner, the weak layer may be more reactive to additional loading. While there has been some time for the snowpack to adjust to the recent snowfall load, continued loading increases the risk of large to very large natural avalanches occurring on this persistent layer. The combination of fresh wind slabs that will be sensitive to human triggering combined with further strain on the deeper, persistent weak layer will keep the avalanche danger elevated again tomorrow. You can expect fresh wind slabs one to three feet thick plus the lingering concern of triggering a very large avalanche on the deeply buried facets. All forecast areas will have a Considerable danger rating at higher elevations. The danger rating will increase to Moderate on steep slopes at lower elevations.
