Quick report
- Red Flags
- Recent Avalanches, Heavy Snowfall, Wind Loading, Cracking, Collapsing, Poor Snowpack Structure
- Red Flags Comment
- <p>Very large natural avalanche from one of the slide paths on the backside of Raymond Slabs in Main Porter Fork - submitted as a separate avalanche observation.</p>
The photo from below is of a snowpit I dug at 9,300' in Main Porter on January 23. It shows the very poor structure, with weak facets and depth hoar in the bottom 60-75 cms of the snowpack. The only difference is there is now a 1-1.5 meter slab on top. There have been very large natural avalanches in Millcreek Canyon the past few weeks, and recently in West Porter and also In Between in Main Porter. The runouts for these slides are running very long distances, much further than is expected.
It is pretty simple - expect very large and dangerous avalanches that are with ~25-year returns, and possibly creating new avalanche paths.
The avalanche danger on 2/16 was rated as "Extreme" which is defined as (1) "natural and human triggered avalanches are certain", (2) "large to very large avalanches in many areas", and (3) "avoid all avalanche terrain". While performing field work today, we adhered to this travel advice and avoided slopes > 30° (in fact we traveled on slopes significantly less steep) and avoided avalanche runout zones.
Snowpack
- Instability Comment
- <p>Very weak snowpack structure in Millcreek Canyon. Increasing danger with additional snow in the forecast.</p> <p>New snow was cracking and collapsing very easily at the interface with the old snow surface. This is now down 30-60 cms. Avalanches initially failing in the new snow could step down to the buried PWL's. </p> <p> </p> <p>Increasing danger with additional snow forecasted for Wednesday.</p>
45 cms settled storm snow on top of the low-density stellars from the interface with the old snow surface. Lots of dense graupel throughout the storm snow.