0915 AM PST SUN DEC 30 2007...AMD && ZONE AVALANCHE FORECASTS...AMD * OLYMPICS, MT HOOD AREA, WASHINGTON CASCADES NEAR AND WEST OF THE CREST- ...AVALANCHE WARNING FOR SUNDAY... High avalanche danger below 7000 feet Sunday, with greatest danger on southeast through northeast exposures. Slowly decreasing danger expected later Sunday night and early Monday becoming high above 5 to 6000 feet and considerable below. Further gradually decreasing danger on Monday, becoming considerable below 7000 feet. * EAST SLOPES WASHINGTON CASCADES- ...AVALANCHE WARNING FOR SUNDAY... High avalanche danger above 4000 feet and considerable below on Sunday. Danger slowly decreasing later Sunday night and early Monday, with further decreasing danger expected Monday, becoming considerable above 4000 feet and moderate below late Monday. * OUTLOOOK FOR TUESDAY- Slowly increasing danger is expected on Tuesday, mainly in the Olympics and on lee slopes in the Cascades especially north and northwest exposures near higher ridges and west facing slopes near the Cascade passes. Further increasing danger likely Tuesday night and early Wednesday. SNOWPACK ANALYSIS Increasingly heavy snow and strong winds late Saturday through early Sunday have loaded a variety of recently buried weak snow layers as well as large amounts of slowly settling older snow. This weather has produced increasingly unstable and more cohesive wind slab snow in most areas. A generally high avalanche danger should be accentuated on southeast through northeast exposures, where natural and human triggered slides are likely. While most field reports prior to the increasing snowfall late yesterday indicated primarily small 6 to 12 inch soft slabs releasing on lower density snow received during lighter winds and showers and cold temperatures last Wednesday, some isolated but larger slides were still being triggered by both explosives and skiers on the weakening and faceting crust that developed early last week. Some of these slides reached 2 to 3 feet or more. Recent stability tests from highway and ski area professionals indicate the continued existence of some easy shears both within the new snow from the past few days and near the Christmas eve crust. Unfortunately now there is also a recent report of a natural 6-8 ft slab releasing down to the old faceted early December crust this occurring around the 5000 ft level on a north facing slope called Machs Coulir in the Alpental Back Country. Although recent snow settlement and gradual insulation of this layer from colder surface temperatures are helping this layer to very slowly stabilize and strengthen, this troublesome and weak bed surface is closer to the surface along the Cascade east slopes. Also it may still be relatively close to the surface on steeper slopes that have already released on this old crust. Hence, while it is a slowly decreasing problem in most locations near and west of the Cascade crest, it may still be a more immediate concern in the overall shallower snowcover along the Cascade east slopes, especially in the northeast Cascades where only limited warming occurred during much of December. And it may once again become a concern west of the Cascade crest if future heavy rainfall occurs. DETAILED FORECASTS SUNDAY...AMD Heavy snowfall and strong winds are expected Sunday, especially in the Olympics and Cascades near and west of the crest. This weather should maintain or slightly increase the generally high danger as an increasingly sensitive snowpack develops along with progressively larger wind slabs, especially on lee slopes. Shooting cracks, extensive fracture propagation and sympathetic slides should become likely Sunday, and increasingly large cornices may be very sensitive as well. Avalanches which initiate in the most recently deposited wind slab snow may step down to older weaker layers, with more isolated larger slabs possibly reaching the old early December crust, especially in higher terrain along the Cascade east slopes. While the expected very strong winds may also scour some wind exposed terrain to higher density snow near the old crust from earlier in the week and produce a wind hardened snowpack with an associated lower danger, nearby lee slopes should be heavily loaded, with wind deposits and associated fractures possibly developing lower in the path than normal. As a result of the anticipated poor weather and visibility conditions as well as the increasingly unstable snowpack, back country travel in avalanche terrain is not recommended Sunday, and travel should be confined to lower angle terrain not connected to steeper terrain above. SUNDAY NIGHT, MONDAY Slowly decreasing winds and showers expected Sunday night through early Monday should allow for a gradual decrease in the avalanche danger as new wind slabs begin to settle. However, low temperatures and the existence of more deeply buried weak layers should make this a very slow process. Further decreasing light showers, light winds and slow clearing later Monday morning and afternoon should allow for a further slow decrease in the danger as both surface slabs and buried weak layers continue to slowly settle and strengthen. However, significant winds slabs and a considerable danger should persist in wind loaded terrain and travelers are urged to perform stability tests and use proper route selection and travel techniques when venturing into avalanche terrain. It should also be noted that in wind sheltered areas experiencing clearing Monday night, some surface hoar formation is possible. If it occurs, this weak layer may become an important factor in future avalanche activity if it survives the warming and/or filtered sun anticipated for Tuesday. MONDAY NIGHT, TUESDAY Increasing winds are expected late Monday and early Tuesday, along with increasing clouds, slow warming aloft and some light showers in the Olympics and north-central Cascades late Monday night and early Tuesday. This should be followed by further light rain or snow in the Olympics, but partly cloudy skies in the northern Washington Cascades decreasing to mostly sunny skies in the southern Cascades and Mt Hood area. In the Washington Cascades and Mt Hood area, the warming aloft and expected moderate to strong winds should help to maintain or slightly increase the avalanche danger, with greatest danger shifting onto northwest through northeast exposures near higher ridgelines. Near the Cascade passes, a cold easterly surface flow should limit warming related effects and shift greatest danger onto west facing slopes. However in the Olympics, the combination of warming, winds and light to moderate rain or snow should produce a more significant increase in the danger. Increasing light to moderate rain or snow spreading to most areas Tuesday night into early Wednesday should combine with moderate to strong winds and slow cooling to produce a further and more general increase in the danger as increasingly dense snow or rain begins to load the upper part of the recently stabilizing snowpack that consists of generally lower density snow or wind slabs. &&