Meteorologists have had surprisingly little to go by when estimating snowfall in spots where winter gales and storms blow — like in the Norwegian mountains.
The problem that plagues meteorologists in pursuit of precise precipitation measurements boils down to gauge design. The typical snow gauge measures solid precipitation by catching snow in large plastic buckets. Weather stations on mountain plateaus are whipped by the same winds as hapless skiers — snowflakes race by in a blur, more or less horizontally, so that only snow that is blown right into the bucket gets measured.
Scientists have found a formula for calculating the error in wind bias made by most weather station gauges that measure precipitation. They developed it by measuring precipitation at a custom-built weather station at Haukeliseter in Telemark County.
The gauge has an extra wind shield for a more accurate collection of snow. The double set of wind fences lets only 20 percent of the wind blow through. Inside the concentric fences the snow falls vertically. The test station provides much better measurements than normal weather stations, according to the figures from three winter seasons.
Only ten percent of dry snow blows right by, compared to as much as 80 percent during windy conditions at normal alpine weather stations. The researchers measured amounts of precipitation over a certain size, wind speeds and temperatures. Quantities of snow were measured once a minute, much more often than at standard weather stations.
After they had collected sufficient data they conducted a statistical analysis of the information. First, sleet accumulation does count toward snowfall amounts, but freezing rain does not.
If snow melts continuously on contact, that can be recorded as a "trace" of snow for the period. While it's important to make sure your snowboard is placed in a good position to begin with, sometimes you can't help with strong wind drifts or uneven accumulations, even on that small surface. Drifts can be tricky. As so many of you are aware, snow doesn't always just fall straight down. In fact, blowing and drifting snow is common, especially behind a front and in lake-effect cases.
This can cause some areas to look like they've received many inches or even feet more than they have! So, what happens if your snowboard is caught in an inescapable deluge of snow drifts?
The answer is to take several measurements all across the area, even off the snowboard. You'll want to note where snow may have piled up excessively due to winds. Look for an increase in depth closer to trees, buildings, or any free standing objects.
The trick is to find a few areas that seem to be a little less than average, and a few areas that seem a little more than average and note all measurements. While not totally scientific, it's the best way to get as close to an accurate measurement as possible when the winds are really strong. When you start taking your snowfall measurements, make sure to record them and send them our way. Not only is it a valuable tool for us, but your reports can help us track the heavy bands and more accurately adjust final snow amounts.
We can be reached at OhioWeather charter. The snow should be measured to the nearest tenth of an inch on the snowboard or other collecting surface. If there has been a lot of wind blowing and drifting the snow, it may be necessary to take more than one measurement on the snow board or collecting surface and average the measurements together to get a more representative total. Once you've recorded the new snowfall, clean off your snowboard or measuring surface.
Snow Depth : This is the amount of all snow on the ground and may include snowfall that has fallen in previous events. On your second snowboard, or on a flat piece of ground, measure the total snowfall to the nearest inch. Again, more than one measurement may be needed if there's been a lot of wind or some melting has taken place and the snow is not evenly distributed across your measuring surface.
If more than one measurement is needed, average all the measurements and record the snow depth to the nearest inch. Once you've measured the snowfall, we encourage you to send us your report. There are a couple of ways to do so:. If you're one of our storm spotters, please give us a call on the number provided to you during your training.
Otherwise, send us your report via Facebook or Twitter. Don't forget to include your location in your report. That was just the basics. If you would like more information on how to accurately measure snowfall or information on the other types of useful snowfall and winter precipitation measurements, then please see the following resources:. Snowfall Measurement Guidelines - A comprehensive list of instructions used by our Cooperative Weather Observers for measuring winter precipitation.
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