Agency gathering data to improve rain, snow predictions

Laney Griffo
Meghan Collins, DRI uses Citizen Science Lake Tahoe app to track winter conditions.


It’s 35 degrees in the Lake Tahoe Basin and the weather calls for precipitation. Will it be rain or snow?

Turns out, that is not an easy question for scientists to answer. However, scientists at the Desert Research Institute, with the help of citizen scientists, are trying to find an easier answer to that question with their ‘Tahoe Rain or Snow?’ project.

Keith Jennings, a water resource scientist with Lynker Technologies is the “data guru” on the project.

“In a water resources model, it’s really easy to predict snowfall when it’s cold, so say 20 degrees, it’s almost always going to be snow,” Jennings said. “Same when it’s warm, when it’s 50 plus degrees, it’s almost always going to be rain. However, in the middle zone, particularly the few degrees above freezing, 32 to 40 degrees, even the best methods tend to get it wrong about 40% of the time.”

This project is aimed at perfecting the models to predict rain or snow in those in between temperatures.

How are they doing it?

Meghan Collins, education program manager at DRI deals with the people side of the project. Through the Citizen Science Lake Tahoe app, people login and fill out a simple survey. It asks them if it’s raining, snowing or mixed precipitation at that exact moment where they are. The app then sends that information to DRI along with a timestamp, location stamp and temperature.

Collins said one of the great things about the app is that it allows people to send in questions in real time. A common question she gets is “what is mixed precipitation?”

The simple answer she gives, “if you have to stop and think about it, it’s probably mixed precipitation.”

They started collecting data from January to May 2020 and started again in the fall through the present. They’ve had over 200 citizen scientists collect data.

“The dedication of the community members cannot be overstated,” said Collins, adding that their goal was 200 data points collected and presently, they’ve received over 1,000 data points.

One important thing to note is that this project is not challenging the freezing point, Jennings said it is unequivocally 32 degrees. However, there is a lot of variability in temperature and humidity and how that impacts falling snow.

So, what they are really looking at is what happens to the snowflake between the clouds and the ground.

Why does it matter?

“Rain and snow, depending on the intensity of the storm, can have dramatic differences in societal impacts,” Jennings said.

If the storm is snowy, you could have great skiing but also traffic issues and avalanche danger. If it rains, it could lead to flooding. So knowing what’s coming can help everyone be better prepared.

“Getting the rain or snow wrong can really impact our predictions of traffic delays, accidents, skiing conditions, avalanches, flooding,” Jennings said.

He added that it can also vary within relatively short distances. So, what’s happening in Reno can be different than what’s happening on the drive up to Tahoe and then even within the Basin itself.

“The U.S. has some of the most climatic diversity in the world,” Jennings said.

Knowing how much and what kind of precipitation not only helps in the short term but can also help for long term planning of water conservation efforts and possible drought conditions.

What’s next?

Collins said they are continuing to collect data. They are particularly lacking data from the western slope so she encourages anyone from Donner, Soda Springs down to Auburn to join in.

“We’re reminding people to always keep their eye on the sky,” Collins said.

The first year of the project was funded through NASA and the National Science Foundation’s Established Program to Stimulate Competitive Research grant program. They were able to show the validity of the project.

On Wednesday, March 3, NASA and EPSCoR announced Tahoe Rain or Snow was one of eight projects to be chosen to receive additional funding.

They will be expanding their research to Oregon, Colorado and further down the Sierra Nevada.

To participate, text “winter” to 855-909-0798. or visit

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