1241 PM PDT Tue Apr 05 2011 This forecast applies to back country avalanche terrain below 7000 feet and does not apply to developed ski areas or highways. Zone Avalanche Forecast - Snoqualmie Pass Forecast AVALANCHE WARNING TUESDAY TO WEDNESDAY MORNING Tuesday to Wednesday morning: High avalanche danger above 4000 feet and considerable below. Danger increasing Tuesday night to Wednesday morning. Wednesday afternoon and night: Decreasing high danger above 6000 feet and considerable below. Snowpack Analysis A strong storm began Monday morning, depositing some 10 to 25 inches of new snow in most areas. Strong winds near ridge top caused widespread unstable layers to form on most lee slopes, especially higher terrain. Heavy snowfall and daytime warming produced some natural avalanches Monday, however many of these paths have already reloaded with new unstable layers. Unstable conditions were reported at the Mt Baker and Stevens ski area by field professionals early Tuesday where ski triggered and explosive releases had extensive propagation and were sensitive, despite significant new snow settlement rates. In general, most slides were involving storm snow layers up to 1.5 ft deep, but with good propagation and running long distances. There remains a threat for some slides releasing in new snow layers to penetrate a wet snow layer of some 1 to 2 feet thick that may be buried 1 to 3 feet below the surface. Any slides involving these layers would be big and very dangerous, possibly destructive in nature, however predicting which slope would or could slide to these deeper layers is difficult. Therefore we are not recommending travel in avalanche terrain until these unstable wet snow layers strengthen and new unstable layers stabilize. Detailed Forecasts Tuesday to Wednesday morning: Moderate orographic snow showers and moderate to strong westerly crest level winds should maintain or build further unstable wind slab layers on lee slopes, especially northwest to southeast facing slopes. Another frontal system is expected later Tuesday afternoon through early Wednesday. This should cause increasing and strong winds with moderate to heavy snowfall at low freezing levels. This weather will build new unstable layers on similar aspects, mainly northeast to southeast. Natural or human triggered avalanches should remain likely through early Wednesday, especially on steep open lee slopes. Avalanche releases may step down to or entrain underlying wet snow layers making some isolated large slides possible. Travel in avalanche terrain is not recommended Tuesday through Wednesday morning. Wednesday afternoon and night: Gradually decreasing showers are expected later Wednesday and Wednesday night. This should allow for a slow decrease in danger as previous unstable layers slowly consolidate and settle. However, any sun breaks being received later Wednesday may quickly make recent snow unstable and cause wet snow avalanches on steep exposed slopes. Some of these may be quite large in areas that have received significant recent storm snow amounts. Also, large cornice formations may become weak and fail during the warmest part of the day. These conditions will make careful route-finding essential later Wednesday.