9 AM PST THU DEC 26 2007 AMD && ZONE AVALANCHE FORECASTS...AMENDED... * OLYMPICS, WASHINGTON CASCADES NEAR AND WEST OF THE CREST, MT HOOD AREA- Considerable avalanche danger below 7000 feet Wednesday morning and mid-day with greatest danger on southeast through northeast exposures above 5 to 6000 feet. Danger slightly and slowly decreasing mid-late Wednesday afternoon through early Thursday. Danger increasing later Thursday morning and afternoon, becoming high above 4 to 5000 feet and considerable below late Thursday. Further increasing danger likely Thursday night. * EAST SLOPES WASHINGTON CASCADES- Considerable avalanche danger above 4 to 5000 feet and moderate below Wednesday morning with greatest danger on higher elevation southeast through northeast facing slopes near the crest. Danger slightly and slowly decreasing mid-late Wednesday afternoon through Thursday morning. Danger increasing mid-day and Thursday afternoon, becoming high above 6000 feet and considerable below late Thursday and Thursday night. SNOWPACK ANALYSIS...AMENDED... In most areas of the Olympics, Mt Hood area and Washington Cascades near and west of the crest, some 1-2 feet of new snow has now accumulated over the higher density snow or rain crust layers developed last Sunday from the last major warming trend. The most recent 6-16 inches of this snow fell Tuesday afternoon into early Wednesday along with some increase in winds, especially near higher ridges above 4 to 5000 feet. Since this most recent new snow fell on some relatively cold, low wind deposited snow layers deposited on Monday, some soft slabs ranging up to 12-18 inches have developed on lee slopes, and early morning control results near Alpental confirm this with relatively easy, skier triggered soft slabs ranging up to about 15 inches. While the overall considerable danger should be accentuated on southeast through northeast exposures above about 5 to 6000 feet in most areas, some shallower soft slabs may also exist on lee terrain at lower elevations near the Cascade passes. Recent increasing settlement has also occurred both within the most recent snow and the overall snowpack. With the lack of a large additional load, this settlement should help confine most expected instability to the most recently received new snowfall. However, significant sluffing and small soft wind slabs should be probable in most areas on Wednesday. Also, some small surface slabs may step down to weakening and slightly faceting snow near the higher density snow or rain crust from last Sunday, and back country travelers are urged to perform stability tests and slope cuts in protected or smaller test slopes before venturing into more open terrain. Generally lesser amounts of new snow have accumulated along the Cascade east slopes, however a similar snow structure exists and this is helping to maintain a considerable danger with soft slabs probable above 4 to 5000 feet, especially on steeper lee terrain near the crest. It should be noted that although the warming and / or rain event last Sunday has deposited some higher density layers or crusts that should help bridge over the old heavily faceted layer near the ground, the most recent crusts or higher density layers are expected to weaken during the anticipated low temperatures of the week ahead. With extended forecast models indicating increasingly heavy snowfall late this week and over the weekend, progressively larger slides are possible, reaching either last Sundays crust and potentially stepping down to the early December crust. Back country travelers should track this increased potential for both larger direct action and some climax or ground avalanches very closely, and modify trip plans and routes accordingly. DETAILED FORECASTS WEDNESDAY...AMENDED... Moderate to occasionally heavy snow showers should decrease in the Olympics and northern Cascades later Wednesday morning, in the central Washington Cascades during the afternoon and in the southern Cascades Wednesday evening. After maintaining current considerable danger for much of the day, this weather should allow for a slow and slight decrease in the danger later Wednesday afternoon and evening as recent soft slabs slowly settle. However, significant sluffing and mostly shallow soft slab activity should be probable on many slopes on Wednesday, with slabs ranging up to about 2 feet on northeast through southeast exposures above about 5 to 6000 feet. WEDNESDAY NIGHT, THURSDAY, THURSDAY NIGHT...AMENDED... Further briefly decreasing showers and winds should allow for a further slight decrease in the danger Wednesday night into early Thursday as further slow settlement of slabs and underlying weak layers occurs. However, along with some brief partial clearing in some areas, this weather may allow for some surface hoar to develop. By mid-late Thursday morning, light snow should redevelop in most areas, with snow increasing and becoming moderate to heavy Thursday afternoon and evening. This snowfall should be accompanied by moderate to strong winds and a slight and limited warming trend. As a result, generally increasing avalanche danger is expected later Thursday morning and afternoon as new and generally higher density slabs are deposited over lower density snow or some surface hoar that may develop in some areas Wednesday night. Some sensitive 1-2 ft slabs are expected, and human and natural avalanches should become likely. While most instability near higher ridges should be on north, northeast and east exposures, some west facing slope smay be loaded near the Cascade passes. Moderate to heavy showers and moderate to strong winds Thursday night into early Friday should maintain or increase the considerable to high danger which should persist through much of Friday, with greatest danger in all areas shifting onto northeast through southeast exposures. &&