OSNW3 -- you can measure snowfall each hour to find out the rate of accumulation, but you would measure snow depth every 6 hours or when the storm moves out. (that is clearing the board you measure snow depth on)
This is so you don't get an inflated snow depth.
As snow falls, natural melting, settling and compacting takes place, and if you cleared the board each hour, you'd interrupt this process.
When I worked on a weather record project in Minnesota for the State Climatology Office, I saw a lot of this.
So a 25" snowfall would produce a 25" snow depth. Sometimes, especially in the dead of winter, this would be possible, but not all the time.
The storm last weekend here in Denver produced about 20 inches of snow at my house, but it never piled up to more than 10 or 11 inches on the ground because it was so wet and heavy it compacted.
An hourly clearing of the snow board may have made it appear as if I had a 20" snow depth to go along with the 20 inches of snow that fell from the sky.
But due to the weight, settling and compacting, along with some melting because the temperature bounced between 31-33°, it never piled up that deep.
Hope this makes sense...I am writing fast on a lunch hour.