There's More To Measuring Snow Than Just Finding Out How Many Inches Fell
By Chris Spears
DENVER (CBS4) - You've probably taken a snow measurement at some point in your life, and it likely involved a ruler or measuring tape and a place on your deck, the top of a picnic table or a car.
But did you know there's actually a little more to measuring the snow than just finding out how many inches fell?
An official snow observation has three parts.
The first is the easiest - finding out how many inches of snow fell.
It's best to have one representative location that is relatively flat where you can place a snowboard before a snowstorm moves into your area.
A snowboard is a scrap piece of wood that is painted white so that it doesn't retain much solar energy. That will help minimize initial melting as snow begins to accumulate.
If you live in place where large snow events are possible it's a good idea to mark your snowboard with something so you can find it, such as a flag or reflector.
But it's often difficult to measure snow when a storm is windy.
If you feel the measurement on your snowboard is not accurate due to wind then take an observation from 3 or 4 spots in your yard and average those amounts.
Make sure to avoid areas where obvious drifts are located.
Once you measure the snow, clear the board off and place it on top of the snow pack so it is ready for the next event.
The second part of the snow observation involves taking the snow that collected inside your rain gauge and melting it down to find the snow-water equivalent (SWE).
In others words how much water was in the snow.
Rain gauges aren't perfect and can often "undercatch" during a windy snowstorm. Unfortunately there isn't much that can be done to avoid this except to make good notes in your observation.
In an extremely windy storm where you are certain the gauge didn't perform well you can take a core sample of the new snow from your snowboard and melt it down to find out the SWE.
That total can then be compared to the SWE from the gauge melt and potentially even be averaged together if you feel that is the best way to represent the total water in your new snowfall.
Once you have your snow-water equivalent (SWE) the third part of the snow observation is simply finding out how much snow is on the ground.
The amount of snow on the ground is a spatial average and includes any new and old snow.
In the period after a snowstorm you may have several days with no new precipitation, but each of those days will have an entry for amount of snow on the ground.
Official weather observers will note the amount of snow on the ground each day at their time of observation until it has all melted away.
There is a fourth part to the snow observation but it isn't typically done on a daily basis.
It's a core sample of the total snow on the ground, both new and old snow, that is melted down to find out the SWE of your snow pack.
This is how we find out how much water is in the mountains each season to help determine spring runoff and reservoir storage.
Meteorologist Chris Spears writes about stories related to weather and climate in Colorado. Check out his bio, connect with him on Facebook or follow him on Twitter @ChrisCBS4.
