The primary avalanche threat remains persistent slab. In steep, wind-affected terrain above 9,000 feet that held snow from early October, skiers and rider could trigger slab avalanches one to three feet deep. These slabs have the potential to kill or seriously harm backcountry travelers. To avoid this threat, determine if the October rain crust and faceted snow combination is present, and assess the slab properties of the overlying snowpack. Collapsing and shooting cracks are an obvious clue that a sufficient slab exists for propagation of an avalanche. In terrain where the crust/facet combination is absent, avalanche activity is unlikely.
The combination of weak, faceted snow lying on a strong rain crust primarily exists on northwesterly through northeasterly aspects above 9,000 feet. Backcountry travelers could trigger slabs failing on this layer to depths up to three feet in steep, wind-affected terrain.
( Discussion is generated from the previous day's afternoon forecast. )On Friday, expect partly cloudy to mostly sunny skies before cloud cover increases in the afternoon as a weak disturbance begins to move into the region. Light, scattered snow showers could linger overnight in the mountains and return late in the day on Friday. Overnight lows at the higher elevations will drop into the single digits before rising to near 10 in the afternoon. Northwesterly to northerly ridgetop winds will range from 5 to 15 miles per hour.The general avalanche hazard is expected to be MODERATE on Friday. The primary avalanche problem remains persistent slab. Two components are needed for backcountry travelers to encounter this problem. First, the crust/facet combinations needs to be present. It primarily exists on westerly through northerly to easterly aspects above 9,000 feet and dips below 9,000 feet in mostly shaded terrain. Second, there needs to be a strong enough slab to propagate failure of the faceted snow. These two components are fairly straight forward to identify by either knowing where this layer exists and assessing surface conditions, or by digging a snowpit. These slabs could range in depth from one to three feet depending on location. In the Tetons, where more snow has accumulated, slab depths will be on the higher end of the range. Less snow has fallen in the Togwotee Pass and Greys River areas, and shallower slab depths are expected.
