Quick report
- Red Flags
- Recent Avalanches, Heavy Snowfall, Wind Loading, Cracking, Collapsing, Poor Snowpack Structure
- Red Flags Comment
- <p>Numerous bulls-eye clues today with widespread cracking and huge collapses. Wind drifting with sensitive wind drifts. Evidence of either a natural or human-triggered slide in So Long area of Catherines, as well as large repeater in Rocky Point (reported under an avalanche observation.) Weak layers were either density change within recent storm snow or facets. </p>
Very intense, sustained winds blowing above 9000' made for dangerous avalanche conditions today, particularly on slopes with weak faceted snow underneath. The dense, wind-blown snow was quite supportable (ski pens were 5-10 cms) and my concern is this new slab will gain strength, and make those slopes with persistent snow at the base "feel" stable. (But in reality it now will just be harder to trigger avalanches, and that any avalanches will just now be larger.)
Photo below is from Rocky Point, an apparent natural avalanche that connected across ~250'. Mark White had reported slides on this slope on Thanksgiving, and this slope was re-loaded with storm and wind-blown snow. It failed on a layer of facets sitting above the October crust. I submitted this under a separate avalanche observation. Take home for me was that slopes with persistent weaknesses that have avalanched have just re-loaded and are primed for more avalanching.
Although I did not ride south-facing slopes, I did talk to a few parties that were on the south aspects around Michigan City in Grizzly Gulch and they reported the storm snow is supportable and is covering up many of the rocks. With continued danger due to weak facets on slopes facing west through southeast, we may have options for much safer riding on south and southwest aspects.
Snowpack
- Instability Comment
- <p>Heavy snow amounts plus strong winds clearly overloading persistent weak layers.</p> <p>Sensitive drifts found on all aspects above 9000'. On aspects facing generally northwest through southeast, it will continue to be an issue as these drifts are on top of very weak faceted snow. On other aspects, I imagine they will settle out quickly. </p>
Really difficult to determine new snow amounts as so much snow was being moved around by the winds. Winds made Saturday storm snow much denser with an inverted feel.
HS ranging from 45-100 cms (18-40").