Measuring snow is not simple, and recent slushy snows have highlighted this. To begin with, snow that does not accumulate cannot be measured except for its water content. It may snow all day, but if it all melts as it falls, the actual snow accumulation is just a trace.
Snow that accumulates should be measured on a flat, white, non-metallic surface well away from trees or houses. This surface should reside on top of the snow and be exposed so it is as cold as the outside air. Snow compacts as it falls, so the snow should be swept away from the measuring surface and then re-measured no more than once every six hours for as long as the snow continues.
Wind further complicates measurement. Baffles can be installed around the snow board, but often the best snow measurements in windy weather are obtained by making a great many measurements and taking the average.