DENVER — One of the more difficult parts of a snow accumulation forecast is predicting the moment that rain will switch to snow. Just being off by a few hours can mean a difference of several inches.
It's not just a matter of figuring out when the temperature will drop to freezing.
“Maybe you’re driving, and you look at the thermometer in your car and you notice that it's 35 or 36 degrees Fahrenheit and yet there’s snow falling," said research scientist Meghan Collins with the Desert Research Institute. "And you might have wondered, did we just break the laws of physics?”
She said snow doesn’t actually break the laws of physics, but it doesn’t exactly play by the rules either. Snow can fall through relatively warm air and not melt if that air is very dry, like it often is in Colorado during the winter.
So, it's a tricky formula that even the most sophisticated computer forecast models struggle with.
"The transition between rain and snow happens at different temperatures in different storms and it happens differently in different regions," she said.
Collins is helping to run a citizen science research project to help advance the ability for computer forecast models to better predict the rain/snow transition and improve snowfall forecasts.
"We are just asking people to answer one very simple question, what is falling from the sky right now," she said.
The project has the word mountain in it, but you don't have to live in the mountains to participate. More than 1,000 citizen scientists have already submitted more than 40,000 reports from the mountains, the urban areas, and the plains.
Sign up for Mountain Rain or Snow
The project is run on a web-based app. Use your smartphone browser and type in www.rainorsnow.org and follow the instructions. Or if you live in Colorado, text CORainSnow to 855-909-0798 and you will receive instructions by text.
Once you're signed up, just wait from precipitation to start falling and submit a report. Either rain, snow or a mix. Then if the precipitation type changes, submit another report. It's important to make the reports in real-time because the app will send the time and geocoordinates in with your report.
The data will then be cross-referenced with satellite observations and computer forecast model predictions. If errors in precipitation types can be corrected, then overall snowfall forecasts will be more accurate.
“Some people love watching the weather and love talking about it, so this is a way to share that energy with scientists that make a difference,” said Collins.
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