The total depth of snow on the ground at the time of observation is
normally the easiest of the snow measurements, except when significant
drifting has occurred. Snow depth is measured by reading the depth of
snow at the permanently-mounted snow stake or by taking the average of
several depth readings at or near the normal point of observation.
Depth of snow on the ground is measured and reported to the nearest
whole inch.
Special concerns and precautions:
1. The key factor is finding a location for the measurement so that the snow depth that is reported is the average depth of snow for unshaded, level areas, not disturbed human activities, in the vicinity (within several hundred yards) of the weather station.
2. During snowmelt, observers often face the situation where snow melts quickly from south-facing areas, but remains deep in shaded or north-facing areas. An observer should use good judgment to visually average snow depths. in the area surrounding the weather station. For example, if half the ground is bare and half the ground is covered with four inches of snow, an appropriate snow depth report would be two inches. When less than 50 percent of the ground area is covered by snow, then snow depth should be recorded as a "trace."
3. When new snow falls atop a layer of partially melted uneven old
snow, it can be very difficult to find an appropriate point or area to
measure snow depth. Many measurements may be needed to obtain a valid
average, or observer judgment may be required to estimate a value.
Stay away from paved areas and areas with lots of human or animal
footprints in the snow.
4. The depth of hail on the ground at the time of observation can and
should be recorded in the same way as snow depth. Make a remark that
identifies the accumulation on the ground as hail.