Fresh wind slabs will be forming on leeward aspects and will be increasing in size and depth during the day. In some areas these slabs will be forming on firm old snow surfaces and are likely to be easily triggered by the weight of a single person. In areas where the snowpack is shallower, like the lower elevations, the new snow will be increasing the load on persistent weak layers. In these areas some potential remains for slab avalanches to fail on those problem layers. Evaluate the snowpack and terrain carefully. Monitor conditions with an expectation that the hazard will be increase as the day progresses.
West winds will be forming new wind slabs on leeward aspects. These slabs could build to depths of 2 feet and are likely to be easily triggered in steep wind-loaded avalanche starting zones.
Persistent slab avalanches are possible in areas where the snowpack is shallow, less than four feet deep. These shallow snow areas are most prevalent at the lower elevations but can also be found in isolated areas and on isolated terrain features at the mid and upper elevations. If triggered these persistent slabs avalanches could be 2 to 4 feet deep.
A winter storm warning remains in affect for the area through 11pm tomorrow. Although snowfall rates overnight are to be lighter, on Saturday moisture is to increase again with moderate to heavy snowfall expected through the day. Another 6 to 12 inches is possible by tomorrow night. Temperatures are to be similar to today’s with west to southwest winds having averages between ten and twenty mph. The general avalanche danger will be Considerable above 7500 feet and Moderate below that elevation. In all forecast areas at higher elevations, new, soft, wind slabs with depths to three feet could be triggered in steep leeward terrain. These slabs will become more sensitive as the day progresses. The other avalanche problem is a persistent slab problem. Although this problem also exists in all the forecast areas it varies greatly by area. In the Tetons, avalanches involving these old layers are becoming unlikely at higher elevations and remain more of a concern at lower elevations or in areas where the snowpack is shallow. At Togwotee Pass, the snowpack is much shallower, and weak layers are widespread and prominent. With enough new snow, human triggered avalanche activity involving these weaknesses will become likely. The Southwest Trails area is in between. In some areas, deep snow depths have made the triggering of very large avalanches less likely but in other areas, human triggered hard slab avalanches remain possible and careful snowpack assessment is both recommended and essential.
