Accurate and timely snow measurements are critical to NWS winter weather forecast and warning operations. However, obtaining accurate observations can be challenging at times. The following is a brief summary of snow measurement techniques. Please follow the procedures below as closely as possible in order to provide accurate snow reports. We appreciate your efforts!
Before the snow season, observers are instructed to prepare for snow by placing their snowboards in the yard and marking them in order to find them after a snowfall. You can easily make your own snowboard from a piece of sturdy wood, ideally 16" x 16" inches. Paint your snowboard white to prevent the board from absorbing heat and melting the snow prematurely. Snowboards ensure accurate measurements because you know when using a snowboard that you are measuring off a solid surface. There are times, especially early in the season, when snow can be perched on top of the grass in your backyard. Pushing your snow stick to the ground in these instances may overestimate the actual reading. To measure snow, use a snow stick measured in tenths of an inch or use a simple yardstick and convert to tenths of an inch.
Snowboard in yard marked by a reflector
image courtesy CoCoRaHS
Snowboard after snowfall
image courtesy CoCoRaHS
Snowfall is the accumulation of new snow and ice in the past 24 hours prior to melting or settling. Snowfall is measured to the nearest tenth of an inch (0.1). The best way to get an accurate snowfall measurement is to use a snowboard. Measure the amount of new snow on your snowboard, record it, then sweep it clean and set in on top of the snow and you're ready for your next reading. Snowboards work well when little or no wind is involved. However, when windy conditions result in blowing and drifting, your snowboard is more than likely not representative of the true amount that fell. When wind is a factor, take your snow stick and record several readings around your yard. Average those readings to get a representative snowfall measurement.
Snow depth is the total depth of all snow on the ground at observation time. Some observers use a separate board that they do not clear for total snow depth readings. Similar to snowfall readings, if wind is involved one must take several readings around the area and average them for an accurate snow depth value. NWS cooperative observers, Chicago Area Snowfall Team (CAST) and Rockford Area Snowfall Team (RAST) observers measure snow depth to the nearest whole inch. CoCoRaHS observers measure snow depth to the nearest half inch.
NOTE: When taking several readings in your yard to determine an average snowfall or snow depth reading, try and find areas with an even layer of snow that has not experienced significant drifting. Also avoid artificial drifts such as snow banks resulting from snow removal observations.
NWS Cooperative Observers as well as NWS CAST/RAST observers submit their reports via WxCoder. CoCoRaHS observers submit their daily and significant weather reports via the CoCoRaHS web site. Snow reports are also welcome from trained spotters and the general public using the following links:
E-spotter for trained spotters
Submit snow reports for the general public