Avalanche Forecast

Mild daytime temperatures and sunshine Saturday should give way to increased clouds late in the day and a chance of a few showers late. This should allow for shallow surface snow melt, breaking down existing surface crusts through the day where they existed. Cooler settled and mostly stable powder is likely on steeper shaded slopes. 

Small loose wet avalanches should be possible on direct, steep, solar aspects. 

We have lowered the likelihood of triggering an avalanche on an older wind slab, however, it would still be wise to watch for these conditions on specific terrain features. Most likely suspects are steep slopes below ridges or cross loaded ribs, mainly near or above treeline and avoid slopes where being caught in a small slide could have larger consequences, such as slopes above trees, cliffs or where the terrain would funnel snow into a trap, like a creek bed or natural depression.

About a week of fair weather was centered around the New Year. This allowed the significant snow that fell during a strong storm cycle, that ended about Christmas, to settle and stabilize. It also led to extensive surface hoar and near surface faceted snow to develop on non-solar, sheltered slopes. These weak surface snow conditions were from seen in numerous reports both west and east of the WA Cascade crest. On solar aspects, a thin sun or melt-freeze crust formed during the stretch of high pressure. 

Since Sunday, a few inches of steady light snow have accumulated along the east slopes, with up to 12 inches at Mission Ridge with only moderate SW ridge-top winds. 

Tom Curtis was west of Blewett Pass around Iron Mountain, New Years Day and found the December 13 buried surface hoar layer 60 cm down that showed sudden collapses in several column tests, including PST with a firm slab overhead. In this area, the layer was prevalent on NE-E aspects around 5300 ft near treeline. This may be a layer of concern to track or look for moving forward in this specific area. No reports from this area have been received. This layer is likely gaining significant strength due to the mild temperatures this week, however it should still be considered a problem, until ruled out. 

PST End down, 60cm on 20151213 buried surface hoar layer. West of Blewett Pass, January 1, 2016. ENE aspect NTL @ 5330ft. Photo: T. Curtis

The North Cascades Mountain Guides on January 1st and 2nd at Washington Pass generally report good stable conditions and a lack of results in snow pit tests. Minor wind effects have been noted near ridges.

Reports via the NWAC observations page for January 2nd at Blewett Pass, email received at the NWAC from Holden for January 3rd and further reports via the NWAC observations page for January 4th for Stevens and Snoqualmie, and most recently Tuesday the 5th on Red Mountain near Salmon La Sac help confirm the extent of the recently buried surface hoar.

Thanks for this observation posted Tuesday which includes a nice video example! https://www.nwac.us/observations/pk/277/

Avalanche professionals in the Tumwater Canyon area Wednesday reported the 1/3 surface hoar layer about 20 cm down on a NW aspect at 4000 ft, but lacking the cohesiveness to present a slab problem. The surface hoar layer was also found on solar aspects at this elevation. 

Several loose-wet slides were also reported Thursday afternoon depositing wet snow in the Tumwater Canyon area due to warming temperatures.