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RegisterJan 8th, 2015–Jan 9th, 2015
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Avoid steep sun exposed slopes if snow becomes wet in more than the top few inches; small wet loose slides could be problematic in isolated areas. Read the Snowpack Discussion and Detailed Forecast if traveling in the Mission Ridge Area.
A cooler day with increasing mid and high level clouds is expected on Friday. Increased cloud cover should also minimize the loose wet avalanche problems even on steep solar aspects.
We have little information and lower confidence about the Persistent Weak Layer in the Mission Ridge area post storm. Evaluate the snowpack in this area before entering avalanche terrain as it may not be representative of the east Cascades zone forecast.
As a general backcountry travel safety note, watch for terrain hazards (exposed rocks, trees, streams, etc) at lower elevations and on wind scoured aspects. On non-solar aspects with a slick and supportable crust, take extra caution when traversing steep slopes and be prepared to self-arrest if necessary.
East of the crest about 6-12 inches of snowfall Sunday was followed by about 1 to 3 inches of rain on Monday with a warming trend especially on Monday. At higher elevations mainly in the northeast more of the precipitation will have fallen as snow and less as rain before precipitation ended on Monday. A period of freezing rain likely occurred at lower elevations Sunday night.
This led to a natural avalanche cycle east of the crest. Backcountry skier/pro patroller Dan Veenhuizen was on Mt Cashmere on Tuesday and noted debris from large avalanches from Sunday and Monday. At 6900 ft he found what should be the December facet layer at about 90 cm below the surface, however it was not reactive to an ECT. Also from this cycle the North Cascade Mountain Guides reported large avalanches up to D3 in the Washington Pass area, including slides reaching Hwy 20 but not crossing the closed highway.
Mostly sunny and unseasonably warm weather followed mid-week in the alpine while the valleys stayed colder and cloudier. In most areas this weather has led to draining, consolidation and a general resetting of the upper or entire snowpack. While the weather has been pleasant in the mountains, ski conditions have generally been reported as poor over the last few days
No new observations have been received from the Mission Ridge area which saw less precipitation but strong warming as well earlier this week. It is unknown how likely the PWL in this specific area is to human triggering after Sun/Mon loading and the potential supportable crusts in the area. Warm temperatures and a shallow snowpack will have supported rounding of faceted snow in this area.
Facet layer in a pit on Mt Cashmere on Tuesday by Dan Veenhuizen.