0830 AM PDT Wednesday, April 11, 2001 ZONE AVALANCHE FORECASTS..... OLYMPICS. . .WASHINGTON CASCADES. . .MT HOOD AREA. . . Considerable avalanche danger above 4000 feet and moderate below Wednesday, except for a locally high danger on steep sun exposed slopes late morning and afternoon hours Wednesday, especially in areas that have accumulated significant recent snowfall. Avalanche danger gradually decreasing Wednesday night and Thursday becoming considerable above 5 to 6000 feet and moderate below. Avalanche danger increasing Thursday night becoming considerable above 4 to 5000 feet and moderate below. SNOWPACK ANALYSIS.... Significant new snow has accumulated over the Olympics and Cascades on both west and east slopes over the past 24 hours. Most areas received between 6 to 18 inches of new snow. The new snow fell at cooling temperatures and was accompanied by strong and shifting winds. The winds during snowfall were initially westerly Tuesday and shifted to east to northeast winds overnight and early Wednesday. This has built new areas of unstable wind slab on a variety of aspects, especially near ridges and at higher elevations. The recent new snow was deposited over the 15 to 30 inches of snow that has accumulated since last Friday in most areas. This older snow generally overlies a strong melt- freeze crust formed during warm weather in late March. Field reports near Chinook Pass on Tuesday indicated that on exposed southerly slopes at about 6000 feet, a very hard underlying crust had only a few inches of soft snow over it. While recent reports on north facing slopes in the north Washington Cascades west of the crest and from about 5500 to 7000 feet, indicated some 2 to 4 feet of recent snow was overlying the old crust. Therefore, widely varying amounts of recently deposited snow should be expected on varying aspects. Generally good bonding has been reported between recent snow layers with a good bond to the crust. However, there have been some recently reported triggered soft slabs in the north Washington Cascades above 6000 feet, as well as a climax slide triggered from a cornice fall. Triggered soft slabs remain likely on steeper terrain, especially at higher elevations where winds and new snow accumulation were greatest. Backcountry travelers should use extra caution with the significant amounts of new snow available to slide. WEDNESDAY. . .WEDNESDAY NIGHT. . . Mostly sunny except for decreasing snow showers mainly in the south and along the east slopes in the south early Wednesday. The greatest present danger is expected on steep slopes that are receiving sun on the recent snow. This should quickly form unstable slab conditions and likely cause widespread natural slides in steeper terrain. At higher elevations and along ridges, triggered soft slabs of 2 to 3 feet or more are likely in areas that have received the greatest recent snow, such as the volcanic peaks and some east slopes areas. At lower elevations and in wind sheltered areas new unconsolidated snow may release as dry lose slides on steeper slopes while any sun and daytime warming may quickly change these conditions to possible wet slides. THURSDAY. . .THURSDAY NIGHT. . . Cloudy with generally light winds and slightly rising freezing levels Thursday should allow for recently formed wind slabs to gradually settle and strengthen causing a gradually decreasing danger. Increasing snow and wind Thursday night at lowering freezing levels should again form new areas of shallow wind slab over existing low-density snow or previously deposited wind slabs. This should again cause an increasing danger with triggered slab avalanches becoming likely on steeper terrain, mainly at elevations above about 4 to 5000 feet.