Snow on Palomar Mountain in February. File photo courtesy UCSD HPWREN camera network

It snowed in the San Diego County mountains on New Year’s Eve, but new research from Scripps Institution of Oceanography finds the local winters are getting shorter.

After examining snowpack data from 1982 through 2017, researcher Amato Evan found that winters are becoming shorter in mountainous regions of the western United States.

His research shows that the snow is disappearing earlier in the year, which could have implications for state water management and wildfire activity.

Evan analyzed data collected from a network of over 400 snow sensors across the western states. He developed a mathematical formula that allowed him to cut through day-to-day ups and downs in the snowpack and identify trends in how snowpack varies over the course of a season.

“The data used in this study are highly accurate but also very noisy, in that there are a lot of ups and downs with changes in daily and yearly weather,” said Evan. “Part of the challenge was developing a robust method to tease out the signal in these data that is due to the longer term effects of climate change.”

Evan found two key changes in mountain snowpack that were consistent across the western United States. The first is that winters are essentially being “squeezed” from both sides — by expanding fall and spring seasons — thus becoming shorter.

The second is that the snowpack at higher elevations is increasingly showing the buildup and melt characteristics of lower mountain altitudes, which means less snow and earlier melt times.

“The power of this work was the ability to examine how and why snowpack is changing throughout the year,” said Evan.

The study was published in December in the Journal of Applied Meteorology and Climatology.

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Chris Jennewein

Chris Jennewein is Editor & Publisher of Times of San Diego.