Quick report
- Red Flags
- Recent Avalanches
- Red Flags Comment
- <p>We observed the remnants of a sizeable natural avalanche in the Northwest Couloir. I would estimate its size as R3 D3. It ran all the way down the bowl at the base, reaching the flats where there are lots of small pine trees and left a large debris pile. Due to the lack of snow on the debris we were guessing it happened sometime yesterday (Monday.) I'm guessing the initial cause was probably windloading but we were unable to determine whether it stepped down to any persistent weak layers. </p>
We toured on the west side of Mount Nebo today from elevations of 6,000 to 9,800 feet, traveling on predominantly west, northwest, and southwest facing slopes. Our initial plan was to head up to the large bowl below the Northwest and Champagne couloirs and try to get a sense of what the snowpack structure was on high elevation terrain on Nebo. When we reached the bowl and saw the large avalanche debris we decided not to go any further and explore other options instead. We did dig a quick pit on a WSW facing slope at 9,200 feet to make sure that there weren't any persistent weak layers hiding under crusts. We found a very strong and consolidated snowpack made up of several crust layers with slightly softer (1F) snow between, but no weak layers at interfaces. HS here was between 180 and 200 cm. This seemed to be deeper than most areas at this aspect and elevation since we were at the bottom of a steeper slope, where new snow pools and is mostly sheltered from the elements. Not far above this we found a pretty shallow and weak snowpack on a similar aspect that is much more exposed to the wind. We did note that the top layer of new snow was sluffing far and fast on the crust beneath it.
Unfortunately we were not really able to get a sense of whether persistent weak layers are still in play on this side of Nebo. We did lots of pole probing and quick hand tests on the way up and found some areas where the snowpack seemed pretty deep and strong and others where there was lots of weak faceted snow. We were mostly in the woods though, and this side of Nebo is filled with blowdown and bushes at the mid elevations and probably does not give a very good representation of what the snowpack is like in higher, more serious terrain.
Photo 1 is of our snowpit, photos 2 and 3 shows the debris from the avalanche.
Snowpack
Snow was mostly dense powder and graupel in areas we traveled today. The depth of the new snow seemed variable depending on terrain features. In our snowpit we measured 25 cm of new snow but this was at the base of a steeper slope where graupel was likely pooling. On our skin track above this area we were only seeing maybe 2-3 inches of snow on top of a pretty stout sun crust. No warming of the snow today but we did note many rollerballs and small wet loose slides from prior days in steep terrain between 8,000 and 9,000 feet.