Avalanche Bulleting Issued 1059 AM PST Thu Mar 03 2011 WA Cascades near and west of crest - north of Stevens Pass     Forecast Thursday through Friday morning: High avalanche danger above 6000 feet and on lee slopes above 5000 feet, otherwise considerable danger Thursday. Danger slightly and temporarily decreasing Thursday night and Friday morning and becoming considerable below 7000 feet. Friday afternoon through Saturday morning: Danger slowly increasing and becoming high above 6000 feet and considerable below. Snowpack Analysis Most NW mountain locations in the Olympics and Cascades near and west of the crest have now received from 30 to over 50 inches of new snow since the most recent series of strong storms began to buffet the region last weekend, with up to 4 to 9 feet of snow (more on lee slopes) now deposited over the crust region that dominated the NW snowpack from late January to about mid-February. While recent increasing settlement and some weak surface crust formation during warming at lower elevations Wednesday has helped reduce the danger somewhat below 4 to 5000 feet and may be helping to reduce but not eliminate the potential for larger slabs involving more deeply buried weak layers, very strong ridge top winds on Wednesday combined with the warming to create stiffening 1 to 3 ft wind slabs overlying numerous weak layers on higher elevation lee slopes... most notably on northwest through northeast exposures. These buried weaknesses include multiple surface hoar layers, faceted snow near several minor sun or melt-freeze crusts, very low density layers, several graupel layers and more significant faceting near the old MLK crust region. While the recent settlement may be gradually reducing the likelihood or frequency of deeper slide releases triggered by recently developing and stiffening wind slabs, the potential for more isolated but relatively deep slides is by no means gone. Even though recently limited visibility into most avalanche terrain has restricted avalanche observations of late, some natural and controlled avalanche fractures ranging from 2 to over 5 feet on Wednesday indicate a continuing (though slowly decreasing) potential for larger avalanches involving more deeply buried weak layers. As a result of both new winds stiff wind slabs developed Wednesday and the multitude of buried weak layers, a high danger continues above 6000 feet and on lee slopes above 5000 feet with considerable danger elsewhere. Detailed Forecasts Thursday through Friday morning Several moderate weather systems expected Thursday into Thursday evening should maintain periods of increased light to moderate snow in most areas at relatively low freezing levels and slightly decreasing ridge top winds. However, further weak layers are likely during breaks or brief decreases in winds or snowfall, and along with additional slow loading of these and other buried weak layers, considerable to high danger should continue in most steeper terrain...with greatest danger on wind loaded northwest, north, northeast and east facing terrain at all elevations. Decreasing showers and winds later Thursday night thru Friday morning should allow for another slow and temporary decrease in the danger as new wind slabs start to settle, loading rates diminish and slow bonding begins to develop in the upper part of the snowpack. This temporary danger decrease should persist into Friday morning before the next strong storm moves across the area mid-late Friday and increases the danger once again. Friday afternoon through Saturday morning Light snow should develop in the Olympics and northern Cascades during the afternoon, increasing and spreading southeastward overnight. Along with strengthening winds and slow warming, this weather should lead to generally increasing avalanche danger as new and more dense slabs develop over lighter snow layers received during relatively light winds and colder temperatures on Thursday. Although moderate to occasionally heavy snow overnight should become more showery Saturday morning along with slow cooling, moderate winds and moderate snowfall from the showers should help maintain considerable to high danger. Near higher ridgetops, the greatest danger should gradually shift from north and northeast facing slopes Friday afternoon to more easterly aspects Saturday morning. Meanwhile near the passes, a pass wind shift overnight should allow the greatest danger to transition from westerly exposures late Friday to more easterly aspects Saturday morning.