A layer of buried facets still exists above 9250' elevation within the snowpack. At 42cm (23.6") below the surface a 10cm (4") thick layer of unconsolidated snow grains exist that have shown to be reactive in tests with light to moderate pressures. This weak layer has had an additional stress added to it from new snow accumulations & rain. The weight & lubrication combined with temperatures above freezing, may cause this layer to fail under the weight of a human. Very apparent whumphing, or collapsing of air spaces, while traveling across flat land should alarm you. Apply that collapsing mechanism to a steeper slope & you got an avalanche.
One slide-path above Leavitt Rd that is a known "Repeat Offender" faces East & always collects wind deposits. Yesterdays rain likely compromised the shear resistance of a newly deposited wind slab & saturated it to the point of failure. Shearing occurs from added stresses to the pack & often tears away the snowpack vertically as it propagates horizontally on a layer of weakness. This is a very destructive form of avalanche because of the heavy mass & surface area potential it has when propagated across a starting zone.
Many of the slopes steeper than 35 degrees had wet loose avalanches due to rain. The rain saturation of the new snows was visible & became progressively thinner at you ascend. Rain will increase the density of the new snow & only percolates so far before capillary action takes over. The saturated snow sits atop a fluffier, less dense snow & wants to pull itself away somewhat uniformly. We call them roller balls or cinnamon rolls. As a snowmobiler we can notice ribbons shooting off our skis & a track pattern that's unique.
More rain fell higher than initial expectations. Our weather forecast seemed to be getting warmer & wetter every time you'd check. It was noted that surface saturation of the snow was happening with the appearance of roller balls, loose wet & wet slab avalanches. The snowpack starting at 8500' is almost nonexistent. The depth exponentially grows as you near 9500' within a small distance traveled. Please refer to my Snow Pilot graph for further explanation. We still see a persistent slab problem 42cm below the surface @ 9500'. Rain may help dissolve this hazard below 9000' but where it remained neutrally cold & dry we are still seeing reactivity.
Rain fell very high on the landscape. Very little wind was observed during precipitation. The BWRA saw a wet mix of snow & fog, making me feel like I was in Alaska again. Temps struggle to fall below freezing at our weather stations.
This snowpack summary applies only to backcountry areas in the Bridgeport Winter Recreation Area. Click here for a map of the area. This snowpack summary describes general avalanche conditions and local variations always occur. This snowpack summary expires in 48 hours unless otherwise noted. The information in this snowpack summary is provided by the USDA Forest Service who is solely responsible for its content.
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