East Slopes North

Quieter weather has allowed the snowpack to begin to heal since heavy snow and rain fell at the beginning of the week. You may still be able to trigger very large and deadly avalanches on deeply buried weak layers on northerly aspects near and above treeline. Watch for triggering avalanches in wet snow or recently formed storm layers. 

Heavy snow, rain, and difficult travel limited access and information. On Thursday, observers reported another 3-5 inches of snow in the past 24 hours. They reported a widespread cycle of avalanches that occurred 2/28-3/1 up to size D3. They also reported tests on the late January facets (about 5 feet below the surface) and the February 26th facets (under the recent storm) indicate the potential for human-triggered avalanches. Near Harts Pass, observers measured 55" of storm snow which settled to about half that height by March 1st. The weather station at Washington Pass recorded an overall gain in height of snow  38" between the 26th and the afternoon of the 28th followed by rain to 6,500. Enough rain fell to create moist to wet snow surfaces and difficult travel. Cooling temperatures should form surface crusts.

The storm brought a widespread cycle of large to very large avalanches across the zone. NWAC Forecaster, Matt Primomo, reported a couple of crowns on steep, unsupported slopes in the Hairpin valley that were deep enough to involve the late January facets. On Thursday, a snowmobile triggered a very wide slab avalanche, at least D2.5, at 6600-6800ft, NE, near Harts Pass. While we don't know for sure, the crown is estimated to be 5ft deep and may have run on the late January facets. On Tuesday, observers reported triggering a small avalanche, about 1 foot deep on an E-SE aspect at 7,000ft near Harts Pass. The slide started as wet loose that then broke into a slab 10-15 feet wide. Near the Silverstar trailhead, I found the February 26th facets preserved under almost 2 feet of recent storm snow and resting on a crust. Snowpack tests produced sudden results (CTM (SP)) on the layer. Numerous avalanches to size D2.5 occurred on S-SE aspects of Delancey ridge. It appeared that some ran in dry snow on Monday with wet avalanches running later in some of the same paths. On Monday, observers near Harts Pass reported widespread natural avalanches in the new snow, even on small, low-angle features and paths that don't frequently avalanche. By the evening of the 28th, they reported 3 feet of accumulated storm snow. 

On Sunday, observers in the Cutthroat creek area found touchy avalanche conditions in the early storm snow and tests that indicated the potential for triggering the late January facets. One large soft slab up to 1.5ft deep was noted from a SE aspect at 6,700ft. On a similar slope, observers reported remotely triggering a slab avalanche, likely on the 2/26 interface. Numerous small (D1-1.5) loose avalanches were also observed from upper elevations.