It was a crazy storm for December in upper Little Cottonwood Canyon. Temperatures prior to frontal passage were obscenely high, 33ºF at Alta-Collins. The heaviest snow-water equivalent (SWE) rates were just after frontal passage (0.35 inches in 1 hr) and about 2/3 of the 0.99" (SWE) total fell at temperatures at or above 30ºF.
These warm temperatures, combined with the convective nature of the storm, led to very high snow densities, with Alta-Collins recording only 5" of snow. That's a mean water content of close to 20%, although the last inch or two should be lower density. Total snowfall likely decreases rapidly with decreasing elevation below about 8500 ft given the high snow levels during the storm.