I heard it was coming and knew it was just a matter of time before it actually got here but it was still a surprise to wake up and see snow on the ground. It is still snowing and the weather report says more is coming too.
Some people think of this as one of those awful four-letter words but I love the changing Nebraska seasons. Sometimes we are lucky enough to see all of them in one day :)
It has been quite a while since I last wrote a NeRAIN newsletter so some of you newer volunteers may have never received one before. The website has been running pretty smoothly, and the reports have been coming in so consistently that I just didn't see a need for one but relearning how to measure snow is a good reason to send one out again. Since it has been a while, this will be a rather long newsletter but please read to the end to learn how to enter snowfall data or to learn what to do if you don't want to track the snow.
Keep in mind that, just like being a volunteer for NeRAIN, measuring and recording snowfall is not required. If you choose not to do so, just take in your rain gauge for the winter and please be sure to rejoin our efforts next spring when the precipitation is more to your liking.
I didn't encourage this last year because I had never measured snow myself. At the beginning of last winter, I wasn't sure if I would continue but after doing it all last year, I found it really wasn't that much more effort. Consequently, this year I DO encourage you to at least give it a try. If you decide to discontinue at any time for the winter, again just take your equipment inside and wait for spring.
WHAT TO DO?
You are measuring and reporting three things:
· TOTAL PRECIPITATION which includes both the rain and the melted water content of the snow that fell. This is the content of your gauge, melted and measured in your inner measurement cylinder. You may use your 'core sample' as your reported precipitation if the gauge catch was obviously less than what actually fell.
· NEW SNOW, which is the maximum accumulation of fresh snow that fell since your observation the previous day. This means if the new snow had been 2.5 inches deep last night but by the time you went out at 7 AM the next morning it only measured 1.5 inches, then the amount of fresh snow you should report is 2.5 inches -- the maximum new accumulation prior to melting, settling or blowing. Snowfall is reported to the nearest 0.1 inch
(If the snow has fallen and accumulated fairly uniformly, then a single measurement of fresh snow on your snowboard or preferred snowfall measurement location may be adequate. But if it was windy, and the snow has drifted, then you will need to take an average to get a representative estimate.)
· TOTAL DEPTH OF SNOW. This is the total of both new and old snow remaining on the ground at 7 AM. -- rounded to the nearest 0.5 inch
In addition to these measurements, we also encourage you to take a core sample of the fresh snow that has fallen in the past day. Sometimes this is a better actual measurement than what has landed in your gauge.
If your core measurement is greater than the precipitation catch in your gauge, and you are confident that your core measurement is a good and consistent measurement, then please enter your 'Core' measurement in the 'Precipitation' column as well as the 'Core' column.
Write down the actual gauge catch in the 'Remarks' so we can confirm how they compared.
· Do not get confused and enter your snowfall in the 'precipitation' column. That happened a few times last year. 'Precipitation' is simply the melted water content. Please don't get confused. Likewise, do not enter the water content of the snowfall in the 'Snowfall' column.
· Always take a look at the ratio between your reported precipitation and the snowfall. A wet snow will have a ratio of about 10 inches snow to each 1 inch of water (10% water) Most Nebraska snows are less dense and average 7-8% water or around 13 inches of snow per inch of water content. But we can sometimes get very dry, fluffy low-density snows with less than 3% water. For example, we have seen 5 inches of snow with only about 0.05 to 0.15 inches of water content.
· You need to remove the inner tube and funnel and bring them indoors. You should only be catching fresh snowfall in the large outer cylinder.
· Our gauges are not perfectly suited for measuring the water content of snow falling from the clouds. They work OK if winds are light or if you are in a nice protected location. However, for wind-driven snow, our gauges will usually catch only a portion of the snow that falls. To get the best sample, you may need to change the location of your gauge to a spot closer to the ground or more protected from the wind to more accurately capture the true precipitation.
But for wind-driven snow it is nearly impossible to find an ideal location to measure. You may need to make wise and objective estimates
If snow sticks to the rim of the gauge, it may not be obvious how much should be brushed into the inner cylinder for measurement and how much should be knocked off. I advise taking a smooth, flat surface and pushing it straight down on top of the gauge. It will knock some snow in and some out, but at least it is a consistent and objective method.
· If your gauge catch seems too low, then take a snow core and compare the water content with your regular gauge. Remember, that your core sample should only include fresh snow from the past 24 hours for comparison.
There is a bit more to it than this and you can refer to the NeRAIN website for additional information. Here is the direct link for how to measure snow:
If you still have questions after reading this newsletter and reviewing the website information, be sure to ask. It is MUCH easier to get data into the database right to start with than it is to try to clean up errors later.
Thanks again for volunteering for NeRAIN.
Nebraska Department of Natural Resources
301 Centennial Mall South
P.O. Box 94676
Lincoln, NE 68509-4676