130 PM PST MON DEC 17 2007 && ZONE AVALANCHE FORECASTS * WASHINGTON CASCADES NEAR AND WEST OF THE CREST GLACIER PEAK NORTHWARD- High avalanche danger above 4-5000 feet and considerable below Monday. Avalanche danger decreasing and becoming considerable below 7000 feet Monday afternoon and night. Increasing considerable avalanche danger below 7000 feet Tuesday. Avalanche danger slightly decreasing Tuesday night. * OLYMPICS, WASHINGTON CASCADES NEAR AND WEST OF THE CREST SOUTH OF GLACIER PEAK- Considerable avalanche danger below 7000 feet Monday slightly decreasing Monday afternoon and night. Increasing considerable avalanche danger below 7000 feet Tuesday. Avalanche danger slightly decreasing Tuesday night. * MT HOOD AREA- Considerable avalanche danger below 7000 feet Monday slightly decreasing Monday afternoon and night. Increasing considerable avalanche danger below 7000 feet Tuesday. Avalanche danger slightly decreasing Tuesday night. * EAST SLOPES WASHINGTON CASCADES- Considerable avalanche danger above 5-6000 feet Monday and moderate below slightly decreasing Monday afternoon and night. Increasing considerable avalanche danger above 5-6000 feet and moderate below Tuesday. Avalanche danger slightly decreasing Tuesday night. SNOWPACK ANALYSIS Over the 24 hours ending Monday morning Hurricane and Mt Baker received about 12 inches of new snow, with about 5- 9 inches at other locations near and west of the crest, and lighter amounts in the lower Cascade passes and along the east slopes. This snow generally fell with strong southeast winds along the crest changing to southwest on Sunday. Blizzard conditions were reported from Hurricane Ridge on Sunday. This brings snowfall to about 1.5 to 4 feet for Hurricane and locations near and west of the crest since the avalanche cycle and rain event early in December. A general expected snow structure should be about 1-3 feet of snow over thinner lower density snow layers, thin crusts, or old hoar frost layers, over the crust formed early in December. A similar but shallower structure might be expected along the Cascade east slopes. This is a snow structure that should warrant a lot of caution. The main chance of slab layers should be on lee north to east slopes but slab layers might be possible on other lee slopes. Note that a high avalanche danger is forecasted today near Mt Baker due to the heavy snowfall in that area. Some reports from the weekend: the NPS reported that a skier triggered 1 meter deep avalanche on a north slope at about 5200 feet Hurricane Ridge on Saturday, many easily triggered 12-14 inch slab avalanches by the Mt Baker ski patrol on north slopes from 45-5500 feet on Saturday, and significant skier triggered avalanches on the unopened International run at Alpental by the ski area on Saturday. A couple other reports of evidence of instability or the layering indicated above for Saturday and Sunday are to be found on Turns All Year, along with some reports of good snow conditions on lower angle slopes. MONDAY AND MONDAY NIGHT Southwest crest level winds and light to moderate orographic snow showers should decrease Monday morning. A relative break should be seen in most areas Monday afternoon and evening. This should maintain local slab layers on lee slopes along with the potentially unstable snow structure. We recommend caution and safe travel routes if you decide to travel in back country areas on Monday. The relative break in the weather may cause a slight avalanche danger decrease Monday night. TUESDAY AND TUESDAY NIGHT Another front should move generally south to north over the Olympics and Cascades on Tuesday. Strong south to southeast winds along the crest should change to southwest, with east winds changing to light west winds in the lower Cascade passes Tuesday afternoon. Snowfall should be heaviest on the volcanoes, in locations exposed to south flow, and possibly along the Cascade east slopes. This weather is likely to build new slab layers on mainly northwest to northeast slopes at higher elevations, and load the previous local potential unstable snow structure. We would consider natural slab avalanches possible and triggered slab avalanches likely on steep lee slopes on Tuesday. This obviously means we continue to recommend caution and safe travel routes if you decide to travel in the back country on Tuesday. Another short relative break in the weather may cause a slight avalanche danger decrease Tuesday night. &&