Quick report
- Red Flags
- Cracking
- Red Flags Comment
- <p>Widespread cracking was found in two main areas. Wind loading from cross loading as well as typical down slope loading were creating wind slabs of varying densities with cross loading in the upper reaches of the USA bowl developing one finger hard wind slabs that were cracking with trail breaking on slope angles of less than 30 degrees. This cracking was enhanced by the hollowness of the snowpack because of the bushiness of the terrain. Of note, when one person rode the rider's right line off the peak of West Monitor we experienced a significant spider-web/window paining to the rider's right of his tracks. As the rider descended and was into his 15th turn he under cut a steep rollover to his right and a series of stress fractures were created without the slope fully moving. These stress fractures left gaping cracks ranging from one to three inches wide. The stress cracking area was rather large: at least 80 to 100 feet wide and 60 to 80 long/running downhill.The slope that fractured was NNW and it had old snow left over from the event on 10/21/12. The old snow was around 7 to 9 inches deep with warm/damp snow at the ground surface and up about 1 to 2 inches deep. Then there was a hollow area directly above this damp snow where there were moderate sized facets up to 6 inches deep and this was capped with a m/f crust. The fracturing broke at the interface of the damp grains and the facets.</p>
Poor snowpack structure in areas that had old snow will continue to present issues.
Snowpack
- Instability Comment
- <p>The primary avalanche issue appears to be related strictly to areas where there was old snow before this last big event from the past 48 hours. Deep slab issues, though soft slab in nature, appear to be of significant concern with the potential for releases going up to three to at least four feet deep. Basically full depth releases and in some ares where there is now significant wind loading may result in slabs of a thicker density and greater depths. </p> <p>As the new snow pack settles and the soft slab densifies these areas where there was old snow may present a more tricky problem. As the new snow begins to bridge these basal weaknesses these hair trigger sensitivities may become a bit more stubborn allowing riders to get further out onto suspect slopes before they initiate possible/potential propagating weaknesses. </p>
The second big impulse that went from Saturday evening through Sunday morning was a bit more dense than the first wave from Thursday evening through Friday. New snow amounts ranged from 11 to 17 inches in this last wave, and it came in with a bit more turbulence wind wise resulting in a mixture of graupel, rimed stellars and light density stellars. As a result there was a bit of a density inversion to the upper layers of the snowpack. This interface continued to yield easy shears throughout the day. Regardless, new snow fall amounts in the past 48 hours stacked up to amounts ranging from 34 inches at 8000 in Silverfork to upwards of 38 inches on the upper elevations on the Park City side of the range. These figures combined with some areas where the old snow had up to 9 inches and the deepest total season settled snowpack was coming in around 42 inches.