Scientific data show citizens that traditional hydrological models may mistake snow for rain

Weather monitors in Tahoe, rain or snow, help reduce inaccuracies in estimating precipitation in the Sierra Nevada

Renault, Nev. (February 22, 2021) – Usually, we think of the freezing point of water as 32 degrees Fahrenheit – but in the world of weather forecasting and hydrological forecasting, this is not always the case. In the Lake Tahoe region of Sierra Nevada, the switch from snow to rain during winter storms may actually happen at temperatures close to 39.5 degrees Fahrenheit, according to new research from the Desert Research Institute (DRI), Lynker Technologies, and citizen scientists from the Tahoe Rain Project or The snow

The new newspaper published this month in Frontiers in Earth Sciences, Data collected by 200 volunteer weather observers to determine the temperature between rain and snow in the winter storms that occurred during the 2020 season. Their results have implications for the accuracy of water resource management, forecasting of the weather, and more.

“Scientists use the temperature threshold to determine where and when a storm will switch from rain to snow,” said Keith Jennings, Ph.D., but if this threshold is turned off, it could affect our expectations for flooding, snow accumulation, and even avalanche formation., Water Resources Scientist at Lynker Technologies and Sun. Lead authors of the study.

Previous studies have found that the thresholds in use are a particular problem in the Sierra Nevada, where a large proportion of winter precipitation drops near 32 degrees Fahrenheit. As the temperature nears freezing, weather forecasts and hydrological models have a hard time predicting correctly whether or not it will rain or snow.

Tahoe Rain or Snow was launched in 2019 to meet the challenge of enhancing forecasting of snow and rain accumulation that would lead to floods by making real-time observations of winter weather. The team consists of two scientists, an educational specialist, and approximately 200 volunteer weather observers from Lake Tahoe and the Western Cliffs regions of the Sierra Nevada and Truckee Meadows.

“Tahoe Rain or Snow harnesses the power of hundreds of local volunteers. The real-time observations they share with scientists add an incredible amount of value to studying hydrology and underscore the critical gaps left by weather models,” said Megan Collins, DRI’s Education Program Director and another lead author on the paper.

In 2020, these citizen scientists provided more than 1000 time stamped and geo-tagged observations of the precipitation phase through the Citizen Science Tahoe mobile app. Ground observations made by the Tahoe Rain or Snow Team in 2020 showed that a warmer temperature threshold of 39.5 degrees Fahrenheit for dividing precipitation into rain and snow may be more accurate for our mountainous region. In contrast, a 32 ° F rainfall and snowfall temperature threshold would predict significant precipitation, resulting in an apparent reduction in snow accumulation. These model errors can lead to problems with water resource management, travel planning, and avalanche risk forecasting.

“Scientists from Tahoe citizens, rain or snow across our region, are opening the door to improving our understanding of winter storms,” ​​said Monica Arenso, Ph.D, Associate Research Professor of Hydrology at the Direct Penetration Institute and another lead author on the paper. “The development of our team of volunteer scientists is important because climate change causes less precipitation with less snow, and it helps reinforce the precipitation forecasts we rely on for the Sierra Nevada and Truckee Meadows.”

Tahoe Rain or Snow continues in 2021. To join, send WINTER to 877-909-0798. You will learn how to download the Citizen Science Tahoe app and receive alerts on good times to submit weather notes. Tahoe Rain or Snow especially needs notes from sparsely populated, remote, or remote areas of the Sierra Nevada.


more information:

For more information about the Tahoe Rain or Snow Project, please visit: https: //www.Dr..Edo /The project /Tahoe, rain or snow /

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