900 AM PST TUE DEC 4 2007 && ZONE AVALANCHE FORECASTS * OLYMPICS- Considerable avalanche danger above about 5000 feet and moderate below Tuesday and Tuesday night and gradually decreasing. Further decreasing moderate avalanche danger below 7000 feet Wednesday through Wednesday night. * WASHINGTON CASCADES- Considerable avalanche danger above about 4000 feet and moderate below Tuesday and Tuesday night and gradually decreasing. Further decreasing moderate avalanche danger below 7000 feet Wednesday through Wednesday night. * MT HOOD AREA- Considerable avalanche danger above about 4000 feet and moderate below Tuesday and Tuesday night and gradually decreasing. Further decreasing moderate avalanche danger below 7000 feet Wednesday through Wednesday night. SNOWPACK ANALYSIS The existing snowpack structure prior to this weekends storm cycle was ripe for a big danger increase and indeed that is what happened. The snowpack structure was primarily a very shallow old snowpack with 1 to 2 feet of low density snow lying above surface hoar or well developed faceted snow formed during the fair and cold weather in late November. This snowpack began being loaded with heavier density wind deposited snow late last week and again Saturday through Sunday. By Sunday the rising freezing levels, continued heavy precipitation and very strong winds initiated a widespread avalanche cycle. This cycle continued Monday as heavy precipitation at further rising freezing levels followed the heavy snowfall and strong winds from late Saturday and Sunday. There were numerous reports of the unstable conditions and natural avalanches that occurred throughout the Cascades through Monday. Many of these can be viewed on the information exchange page on the FOAC web site http://www.avalanchenw.org/cgi-bin//search_reports.php as well as Turns All Year and others. The current danger has diminished as a result of the avalanche cycle along with currently decreasing precipitation, diminishing winds and gradual cooling. Although this is causing a saturated snowpack resulting in considerable wet snow instabilities. Snowpack melt and consolidation has been generally between 1 to 2 feet since it peaked in depth late Sunday. Backcountry travelers should be aware of the continued possibility of triggered avalanches, especially on steeper terrain or on slopes that did not release naturally over the past few days. These might include lower angled slopes that did not recently slide. Terrain and vegetation may still be anchoring a shallow snowpack at low elevations especially east of the Cascade crest. But be aware of the slopes you are connected to that may extend to higher elevations where quite different avalanche conditions may exist. Slides generated at higher elevations may reach run out zones where a much shallower snow cover exists. TUESDAY AND TUESDAY NIGHT Gradually diminishing but still relatively strong westerly crest level winds along with moderate rain or snow and slowly lowering freezing levels is expected Tuesday. This should begin to refreeze the old wet snowpack at higher elevations but maintain unstable wet snow at mid and lower elevations. Further cooling along with light to moderate rain or snow mainly along the west slope areas late Tuesday and Tuesday night should begin to build some new unstable layers on lee slopes at higher elevations. At lower elevations the cooler temperatures and consolidated snow should result in a significantly decreasing avalanche danger. WEDNESDAY AND WEDNESDAY NIGHT Further cooling with light to occasionally moderate snow showers and decreasing light to moderate winds early Wednesday should allow for refreezing of the old wet snowpack and also develop some new unstable layers, especially near ridges at higher elevations. Showers ending with decreasing winds late Wednesday should allow for a further slowly decreasing danger. &&