0830 AM PST TUE JAN 15 2008 && ZONE AVALANCHE FORECASTS * OLYMPICS, WASHINGTON CASCADES NEAR AND WEST OF THE CREST, MT HOOD AREA- Considerable avalanche danger above 4000 feet and moderate below Tuesday morning with greatest danger on northeast through southeast exposures. Danger slowly and slightly decreasing Tuesday afternoon through Wednesday, becoming considerable above 5 to 6000 feet and moderate below, with greatest danger shifting onto southeast through south exposures near higher ridges and slopes receiving sunshine. * EAST SLOPES WASHINGTON CASCADES- Considerable avalanche danger above 5000 feet and moderate below Tuesday morning with greatest danger on northeast through southeast exposures. Danger slowly and slightly decreasing Tuesday afternoon through Wednesday, becoming considerable above 6000 feet and moderate below, with greatest danger shifting onto southeast through south exposures near higher ridges and slopes receiving sunshine. SNOWPACK ANALYSIS Recent weather mid-late Monday through early Tuesday included strong winds, rapidly lowering freezing levels and increasing rain or local freezing rain changing to snow Monday afternoon with some moderate to heavy new snow amounts received overnight. This weather and the formation of some near surface crusts helped to reduce the danger from older buried weak layers of surface hoar and lower density lower wind deposited snow layers, especially at lower and mid elevations and on wind exposed terrain. However, the new snow combined with strong winds helped produce new and in some cases hard wind slabs on southeast through northeast exposures, especially above about 4 to 5000 feet where a considerable avalanche danger exists. At lower elevations some shallow wind slabs should be relatively well bonded to a moderate rain or freezing rain crust formed yesterday afternoon; however some weak layers within the most recently deposited snow should make human triggered slabs up to 6 to 12 inches possible. While a similarly good bond should exist between larger amounts of new snow and a weaker and very thin crust or refreezing wet heavy snow layer at higher elevations, more of the recent precipitation fell as snow and stronger winds should have created larger wind slabs over the weaker crust or denser snow layers. Although the high winds should have scoured much of the new snow down to a fairly stable wind hardened or crusty surface on wind exposed terrain above 4 to 5000 feet, the same winds should have produced a considerable danger and unstable wind slabs ranging up to 1 to 3 feet on wind loaded northeast through southeast exposures. Field reports early Tuesday indicate several easy to moderate shears within the most recently deposited new snow, most probably due to brief variations in wind speeds or precipitation intensity overnight. DETAILED FORECASTS TUESDAY Light to moderate showers should rapidly decrease Tuesday morning, along with more slowly decreasing winds and very low freezing levels. This should be followed by widely scattered light showers and partial clearing mid-day with partly to mostly sunny skies Tuesday afternoon. Such weather should maintain existing danger levels Tuesday morning, with continued wind transport of loose surface snow and changing wind direction slowly shifting greatest danger onto south and southeast exposures near higher ridges. While wind speeds should continue to slowly decrease Tuesday afternoon and evening, expected low temperatures should allow for only very slow settlement of existing slabs. Some sun-produced warming Tuesday afternoon may also produce a local increase in the danger on sun exposed terrain where increased natural loose or isolated slab activity and thin sun crust formation are possible. Also note that on lee slopes at higher elevations, slides beginning within the most recent wind transported snow may trigger some isolated deeper slabs reaching buried surface hoar layers formed late last week or over the weekend. TUESDAY NIGHT, WEDNESDAY, WEDNESDAY NIGHT Increasing mid and high clouds are expected to spread southward and thin Tuesday night and Wednesday, with a chance of a few flurries in the extreme north but considerable sunshine or filtered sunshine likely in most other areas. While further gradually decreasing winds are likely Tuesday night through Wednesday night at lower and mid elevations, moderate northerly winds are expected to continue near higher ridges. Finally, while continued low temperatures are likely in most areas through Wednesday morning, slow warming and rising freezing levels are likely Wednesday afternoon and night, especially in the southern Washington Cascades, Mt Hood area and the Olympics. Overall, this weather should allow for recent wind slabs to very slowly stabilize and the danger to gradually decrease. However, a considerable danger should persist on wind loaded slopes above 5 to 6000 feet, and sunshine combined with gradually warming temperatures may produce a local increase in the danger on wind sheltered but sun exposed terrain along with further weak melt freeze crust formation. It should also be noted that cold temperatures Tuesday and Wednesday should allow for slow faceting and weakening of the snow near the crust from Saturday, and some surface hoar is expected to form in wind sheltered locations Tuesday and Wednesday nights. Such developments should be monitored as they may become important considerations when future snow loading occurs. &&