Avalanche danger is on the upswing as a powerful storm makes its way inland on Thursday. This will be a good time to minimize your exposure to avalanche terrain. Avoid it altogether if your area receives the upper end of forecast snowfall.
Moderate to heavy snowfall will layer fresh storm slabs across the region. Expect slabs to increase in size, destructive potential, and reactivity over the day. Lower elevation areas that were below threshold depth for avalanches will be approaching and may exceed this threshold during the storm
Wednesday night: Light snowfall bringing a trace to 10 cm of new snow. Strong southwest winds.
Thursday: Increasing snowfall bringing another 15-30 cm of new snow, continuing but easing overnight. Strong southwest winds. High temperatures at treeline around -1.
Friday: Partly cloudy. Light to moderate southwest winds. Treeline high temperatures around -2.
Saturday: Cloudy with wet flurries bringing 5-10 cm of new snow to upper elevations. Moderate to strong southwest winds. Treeline high temperatures around +1.
Avalanche observations in the region remain very limited, in part due to ongoing access limitations. With that said, forecast weather is currently the most important consideration with regard to avalanche activity. Moderate to heavy snowfall is expected to form widespread storm slabs in areas that have reached threshold depth for avalanches. Slabs may prove especially touchy where new snow has buried surface hoar (recently observed in the south of the region). In areas that see 15 or less cm of new snow, hazard may be more limited to wind slabs forming in the lee of ridgecrests and other exposed terrain features.
Thursday's storm is expected to bring totals of 25-40 cm of new snow to the region under the influence of strong to extreme winds. The new snow will bury previously wind-affected surfaces, however surface hoar was obseved in the south of the region earlier this week. It may also exist in the north. Touchy slabs are very likely to form in any areas the new snow buries these weak grains.
Below the evolving surface, a variable 10-40 cm of older wind-affected snow currently overlies a hard rain crust. Another rain crust exists near the bottom of the snowpack.
Average snow depths in the alpine are 100-120 cm. Snowpack depths decrease dramatically at treeline and below, and are below threshold for avalanching in many areas.
Early season hazards such as rocks, stumps, and creeks are a primary concern at these lower elevations.
