I had 4 1/2 inches on the ground at the start of the storm (which isn’t done, although now at 8 a.m. it has stopped for the moment). Then I got 13 inches of new snow. But I have only 16 inches of snow on the ground.
That’s because, obviously, overnight the more recent snow slowly compacted the earlier snow. This is why snow depth is an inexact measurement of what happens in a storm. Official measurements involve sweeping away fallen snow multiple times during the storm and totaling the results, to lessen the effect of compacting. But what really matters is “snow water equivalent” or SWE, which melts down the final snowdepth to see how much water it contains.
Yesterday’s snow was average in density – 13 inches melted down to 1.33 inches of water, almost exactly the “average” 10% water content.
But the 16 inches on the ground melts down to 2.13″ of water, a denser 13% average. That’s because the original 4 1/2 inches was much more compacted.
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