Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain on Wednesday
Weather Forecast
The region moves into a pattern associated with zonal flow. In short, this means that a series of small disturbances will affect the area as freezing levels remain relatively high, around 1200 m or so. I expect 10 - 15 cm of new Sunday night and an additional 10 - 15 cm Monday. A more organized system is building in the pacific with some pineapple qualities (warm/ moist) The timing is a bit ruff right now, but it looks to move into the area late Wednesday bringing moderate free precipitation and freezing levels rising to 1500.
Avalanche Summary
The new snow was quite reactive Saturday afternoon. Numerous sluff's and very soft slab avalanches to 10 cm in depth were reported.
Snowpack Summary
The initial burst of Saturday's storm delivered 20 cm of cold dry snow. Temperatures began to warm up around dinner time and an additional 12 cm wet heavy snow has fallen as of 2:00 PST Sunday. I feel comfortable calling everything beneath the storm snow well settled. From a technical perspective, we are monitoring the old storm snow which rests on dry cold snow formed during an Arctic Outbreak. A few days ago a Rutschblock test in the north showed a result of RB6, MB down 90 on this layer. In the south a CTE test produced a failure down 70 at this interface. We may see some limited activity out of this layer Sunday, but I think that will be its last kick at the canThis storm will also serve as a litmus test for the Jan. 13th SH/FC layer. With 20 - 40 mm of additional water weight, if it doesn't preform Sunday/Monday, then I think we can move it into the dormant layer category.Deep in the pack the mid December layer has gained a lot of strength and I don't think we'll see any action from this layer until the spring.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.