At the upper elevations, backcountry travelers could trigger wind slabs on a variety of aspects. A slight chance still remains for skiers and riders to trigger a deep persistent slab on shaded and partially shaded slopes above 9,000 feet. Evaluate the snowpack carefully, and identify terrain features where these two avalanche problems could exist. With the exception of small, isolated pockets in very steep terrain, human triggered avalanches are unlikely at the mid and lower elevations.
Southwesterly, westerly and northeasterly ridgetop winds have formed shallow wind slabs on a variety of aspects above 9,000 feet. Skiers and riders venturing into steep, wind-loaded terrain could trigger these slabs to depths of one foot.
Although unlikely to be triggered, persistent deep slabs remain a concern in avalanche prone terrain on westerly through northerly to easterly aspects above 9,000 feet. Large triggers, such as snowmobiles or groups of people, are more likely to be able impact the persistent weaknesses near the base of the snowpack. These hard slabs could have crown depths to six feet. Previous tracks are not an indication of stability.
The National Weather Service has issued a Winter Storm Warning beginning at 5 PM Saturday night and continuing through 5 AM on Thursday. Snowfall began to develop this evening and will increase in intensity overnight. Periods of moderate to heavy snowfall will continue during the day on Sunday. Mountain temperatures might decrease a bit overnight before topping out in the mid 20s during the day. Southwesterly ridgetop winds will range from 15 to 25 miles per hour.The general avalanche hazard is expected to be MODERATE Sunday morning and will rise during the day as new snow, moderate to strong winds and warming temperatures combine to create new wind slabs. During the day or by the evening, the avalanche hazard could increase to CONSIDERABLE at the higher elevations, and skiers and riders could easily trigger these newly formed slabs with depths of one to two feet by nightfall. On shaded and partially shaded slopes above 9,000 feet, the likelihood of triggering deep persistent slabs will slowly increase as the storm adds weight to deeply buried weak layers. Monitor weather conditions and be willing to alter your plans if a rapid loading event occurs. There is also a chance for valley rain in the afternoon, which will be most likely in the southern portions of the forecast area. If this happens, shallow wet slides will become possible.
