How El Niño Could Affect California’s Water Year
Wild precipitation swings in recent years have left Californians asking, "What's next?". Weather Tools has the answer, with a groundbreaking and proven methodology for forecasting California's water year.
The Golden State endured three years of persistent drought, followed by a recent above-normal 2022-23 water year (Oct 1 - Sep. 30) that filled reservoirs and left behind a relieved populace.
There's little doubt El Niño will play a significant role in the overall weather pattern across the country in the coming months. But its effects on California's precipitation aren't as clear-cut as one may think.
Meteorologist Rob Doornbos is the founder and CEO of Weather Tools, Inc., which issues an annual report that forecasts the total water year precipitation across the state. He says both climatic patterns -- an El Niño and its sister pattern, La Niña -- have led to water year precipitation amounts on both sides of average.
"Past El Niño events have shown significant variations in their impact here in California," Rob says. "Some brought much-needed relief, with above-average rainfall and snowpack, while others fell short of expectations," he adds.
Weather patterns such as El Niño or La Niña are paramount to California's economy, considering they significantly influence the annual precipitation patterns and water resources. However, the uncertainty surrounding their outcomes underscores the complexity of the atmosphere and the importance of continued research and innovation for improved forecasts, benefiting businesses and individuals alike.
So, we asked Rob to weigh in on our El Niño questions as they relate to California's water year precipitation forecasts.
El Niño is a climate phenomenon characterized by the periodic warming of sea surface temperatures in the central and eastern tropical Pacific Ocean. This natural occurrence has far-reaching effects on global weather patterns, making it a topic of great interest and concern for meteorologists, climate scientists, and regions vulnerable to its impacts.
Approximately two-thirds of previous El Niño occurrences in California have resulted in above-average precipitation levels, while the remaining one-third have led to below-average statewide precipitation for the water year. Weather Tools' methodology relies on significantly more than just climate pattern data to forecast precipitation accurately.
Recent research out of UCLA suggests that the periodic fluctuation of sea surface temperatures in the Pacific (referred to as ENSO) explains only about 25% of the year-by-year variability in California’s precipitation and that most of the variability is explained by atmospheric circulation patterns independent of ENSO. The CAP Forecast bridges that gap as its proprietary technique focuses on the requisite atmospheric processes, whether they are ENSO-associated or not.