East Slopes North

The sun and warmer temperatures are helping to settle the new snow, but you could find lingering instabilities with recently drifted slabs, or weaker snow beneath. Heed signs of instability like whumphing collapses, cracking, and steer clear of steep slopes that appear duned with wind drifts. In areas that previously held a shallow snowpack, you could trigger avalanches that run on weak snow near the ground.  

Sunday was a very nice day in the mountain, the sun and warm temperatures did have an effect on snow surfaces that face south. A few new avalanche observations came in: a small wind slab from Blue Lakes Col, a small soft slab from below a tower to the NE of Portly, and numerous small loose snow avalanches. Observers have been reporting fairly widespread whumphing collapses from 2,600ft to 4,000ft over the past few days. These have been in valley bottoms, or areas with very shallow snowpacks from roughly Delancey Ridge and to the east. Collapses at higher elevations appear to be much less frequent, though one observer reported a collapse from a NW aspect at 7,300ft below Blue Lakes Col on Sunday.

A storm passed through over the weekend, and storm totals ranged from 0.5" (Wa Pass) to 1.2" (Harts Pass) of SWE in the zone with 8-12" of new snow. About 3" of snow fell at Washington Pass on the 8th, and covered up a mixed bag of surfaces. At this interface, you'll find sun crusts on steep south slopes, firm wind board, soft, weaker snow, and potentially large surface hoar. While surface hoar may have been blown over by wind in some areas, its likely preserved under the surface of wind-sheltered slopes.

Some other notable observations: On the 8th, Willie spotted an older slide that appeared to have run on a deeper layer near Kangaroo Ridge(see photo below). On the 5th, Josh found impressive propagation with snowpack tests, and multiple parties witnessed collapsing in open terrain below treeline near Goat Peak.

You can find facets from mid-November (buried 11/22) just below the middle of the snowpack on most slopes from Washington Pass into the eastern mountains. It's uncertain if they remain intact as far west as Rainy Pass. We haven't received reports of avalanches on this layer, but it's been the source of numerous reports of collapsing, mostly at lower elevations. The grains appear to be bigger and "sharper" further east. Near and west of Washington Pass and below about 7,000ft the facets received rain and you'll find them just beneath a crumbly crust. The overlying snowpack also varies from west to east with elevation. It's generally deeper as you move west and higher in elevation. Overall, the weak layer seems most problematic where the grains are the biggest, closer to the surface, and have a stiffer slab immediately on top. Big storms could create avalanches on this layer.

Be ready to make your own assessments of the snow and avalanche conditions. Let us know what you see by submitting observations.