RENO, Nev. — Snowflakes can fall through relatively warmer air and make it all the way to the ground without melting, as long as that warmer air below the cloud is very dry. And Colorado is famous for its air.
That means we can get snowfall when the air temperature is as warm as 39 degrees, but other times the snow still melts into rain despite the dry air -- making the rain-to-snow transition one of the tougher things to forecast.
One of the problems is that computer models lack the sophistication to deal with all the variables, like how air coming over mountain ranges can change the pressure and humidity.
There is also a lack of verification. If the computer models don't know their solution for when rain was going to turn to snow was wrong, then they will keep making the same mistakes.
A research project called Mountain Rain or Snow aims to help improve the forecast.
“Our project is working out a series of those probability curves so the models can be a little more nuanced for different locations,” said Meghan Collins, a research scientist with the Desert Research Institute.
Collins said the whole program is centered around one very simple question: What is falling from the sky right now?
She said that very simple question fills a big gap in hydrologic research, and she’d like the answer to that question to come from citizen scientists across the state of Colorado and any other state that has similar rain-to-snow forecast issues.
Weather stations with sophisticated technology that automatically records the type of precipitation minute by minute are spaced too far apart. In most states, there can be more than 50 miles between observations.
Scientists can also use weather satellites to fill in the gaps, but Collins said the data is not fine enough coming from more than 20,000 miles above the earth.
"Sometimes real, old-fashioned humans are the best way to answer a question or make an observation," Collins said.
It's easy to help meteorologists tackle this weather dilemma.
Just log in to the website rainorsnow.app. You can use the browser on your phone or laptop, but if you use your computer, you have to enable location settings so your observation will show the right coordinates.
Then let scientists know what time the rain in your area turns to a mix, and then again when it turns to snow.
The program's name has the word mountain in it, because mountain ranges have profound effects on the conditions that allow snow to fall when the air is above freezing. But you don't have to live in the mountains to participate. Collins said they need a wide range of data from all over the region.
She said they have already received more than 8,000 observations across the country, but most are focused near the Sierra Nevada mountains, where the Desert Research Institute is located. They would like more participants from the Rocky Mountain region, and also the northeast part of the country.
“It’s very powerful that people can get involved and evolve the science much further than scientists can do by themselves," Collins said.
This is not just getting the forecast right to help people plan their daily lives, but Collins said that rain/snow transition forecasts help hydrologists plan. As the climate warms due to global warming, rain-on-snow events are projected to become more frequent, which may deplete our snowpack earlier.