There are some "tricks" to getting a ball park estimate to these two questions.
For a good estimate of the amount of snow on the ground, divide the snow water content by density of the snow. Snow density varies site to site and with time during the winter, but a rule of thumb for most sites is–
Dec 1 = 0.15, Jan 1 = 0.20, Feb 1 = 0.25, Mar 1 = 0.30, Apr 1 = 0.35.
So as an example, in February a site that has 15 inches of snow water (swe), probably has about 15 inches / 0.25 = 60 inches of snow depth. For the most accurate density value
for an area and the elevation you are interested use these:
- Idaho Basin Snow Density vs. Elevation Graphs
To determine how much new snow fell in a recent storm, look at the "Rate of Change Reports" under the Daily Data section of the Current Water Year page.
If the site has a depth sensor the increase in the snow depth is shown for the past 4 days. If the site doesn't have a depth sensor, note the amount of snow water (swe) that the
site gained, then divide that number by 0.10 or 10%, since 10 inches of new snow generally contains 1 inch of water equivalent. For example if a site picks up 1.5 inches of snow water, then according to this rule 1.5 inches / 0.10 = 15 inches of new snow. Take a powder day – we’re sure your boss will understand.