Avalanche Forecast

Due to the high likelihood of human triggering and a variety of avalanche problems expected, dangerous avalanche conditions are forecast along the east slopes of the Cascades Sunday, so stay conservative with your terrain selection. 

Another front will bring more light to moderate rain and snow to the east slopes of the Cascades Sunday, beginning in most areas by mid-morning and turning to light to moderate showers in the afternoon. 

This snow will load the January 3rd and January 11th persistent weak layers were they exist along the Cascade east slopes. This could produce natural or human triggered avalanches that could be remotely triggered, propagate around terrain features and bury, injure or kill.

New wind slab will continue to build mainly on lee northwest to east slopes near and above treeline but should be more varied aspects near the Cascade passes. As the same lee aspects continue to load Sunday, larger avalanches will become possible. 

New storm slab is also likely on varied aspects where winds are lighter and snow rapidly accumulates to deeper than a few inches Avalanches releasing in near surface layers on Sunday may entrain previous snow producing large avalanches.

Deep storm snow that fell during mid-late December is well settled, homogeneous and has stabilized so the current avalanche danger focus will be on the upper snowpack. Fair weather over the New Year caused extensive surface hoar and near surface faceted snow. This was buried by about light to moderate snowfall along the east slopes from about January 3rd-6th. Another fair weather period was seen from about January 7-10th. Surface hoar and near surface faceted snow formed again in many areas during this period. 

The latest report via the North Cascades Guides is from Delancey Ridge on Wednesday where easily triggered wind slab of about 20-25 cm was seen on north and south slopes at about 6000 feet which was releasing on a persistent crust layer buried on January 11th. A 20-25 cm storm slab was also remotely triggered on a south slope at about 5000 feet which released either a persistent crust buried on January 11th or on persistent buried surface hoar from January 3rd. Natural avalanches were also heard in the area.

A couple reports are available for Thursday via the NWAC Observations page. Skiers triggered 10 inch slabs on a crust which may be a persistent layer on north slopes at 6000 feet Silver Star Mountain. Snow pits near Leavenworth had a easy to spot persistent buried surface hoar layer at 35-40 cm from the surface.

On Saturday Mission Ridge pro-patrol found easy 6-8" ski cuts on lee aspects near and above treeline involving new storm snow.  It is thought that the buried surface hoar previously found in the Mission Ridge backcountry on northerly aspects was likely thoroughly tested earlier in the week and no longer a widespread issue in this specific area.