Follow the same rules for a once-a-day observation, but the snow accumulation reported will be the greatest for the previous six hours instead of 24 hours. This is the procedure followed by National Weather Service Forecast Offices. If your daily schedule permits, you may wish to make a snowfall observation every 6-hours, beginning with your regularly scheduled time of observation. Measurements beneath trees are inaccurate since large amounts of snow can accumulate on trees and never reach the ground. In heavily forested locations, try and find an exposed clearing in the trees. In open areas where windblown snow cannot be avoided, several measurements may often be necessary to obtain an average depth and they should not include the largest drifts. Finding a good location where snow accumulates uniformly simplifies all other aspects of the observation and reduces the numerous opportunities for error. It is essential to measure snowfall (and snow depth) in locations where the effects of blowing and drifting are minimized. If snow continually melts as it lands, and the accumulation never reaches 0.1 inches on your measuring surface, snowfall should be recorded as a trace (T) and record in your remarks that the "snow melted as it landed". The total snowfall for that reporting 24-hour day is the sum of the three separate snow squalls, 6.7 inches, even though the snow depth on your board at observation time was zero. The snow from each event melts off before the next accumulation and no snow is on the ground at your scheduled time of observation. For example, three separate snow squalls affect your station during your 24-hour reporting day, say 3.0, 2.2, and 1.5 inches. If snowfall occurred several times during the period, and each snowfall melted either completely or in part before the next snowfall, record the total of the greatest snowdepths of each event and enter in your remarks "snowfall melted during the OBS period". Remember, you want to report the greatest accumulation since the last observation. If your observation is not based on a measurement, record in your remarks that the "snow amount based on estimate". If you are not present to witness the greatest snow accumulation, input may be obtained from other people who were near the station during the snow event. If you are not available to watch snow accumulation at all times of the day and night, use your best estimate, based on a measurement of snowfall at the scheduled time of observation along with knowledge of what took place during the past 24 hours. Snowfall amounts can be measured hourly or at any interval as long as the snow measurement board is NOT cleared more frequently than once every 6 hours. This measurement should be taken minimally once-a-day but can be taken up to four times a day, (every 6 hours) and should reflect the greatest accumulation of new snow observed (in inches and tenths, for example, 3.9 inches) since the last snowfall observation. Measure and record the greatest amount of snowfall that has accumulated on your snowboard (wooden deck or ground if board is not available) since the previous snowfall observation. (See Water Equivalent section below for details)
Observers should determine three values when reporting solid precipitation. Once your equipment has been readied for winter you are prepared for taking snowfall measurements. They should be located in the vicinity of your station in an open location (not under trees, obstructions, or on the north side of structures in the shadows).
Put your snowboard(s) out and mark their location with a flag or some other indicator so they can be found after a new snowfall.
SNOW WAGER TIMES MANUAL
It is easy to forget what needs to be measured, especially in those parts of the country where snow falls infrequently.Īt the beginning of each snowfall/freezing season, remove the funnel and inner measuring tube of the eight-inch manual rain gauge to expose the 8-inch diameter overflow can so that it can more accurately catch frozen precipitation. Doesken and Arthur Judson, CSU, 1996).Įach season before the first snows come: Review these instructions for measuring snow. Some of the materials have been extracted from "The Snow Booklet" by Nolan J. The following procedures were developed from previous National Weather Service procedures and input from a broad array of expertise from climatologists, snow specialists, weather observers, and data users.
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