Breaking Forecast Boundaries: The California Annual Precipitation Report Delivers Water Year Clarity Beyond El Niño's Reach

CHICO, Calif.--(BUSINESS WIRE)--Weather Tools, Inc. unveils the 2023-24 California Annual Precipitation (CAP) report today, emphasizing that water year precipitation is influenced by factors beyond El Niño alone.

The CAP forecasts have successfully verified every year for the last 7 years. No other California water year precipitation forecast has come close to doing the same, making it the most accurate and reliable water year precipitation forecast in California.

A recent study published in The Bulletin of the American Meteorological Society reveals that sea surface temperature fluctuations in the eastern Pacific account for merely 25 percent of the year-to-year variability in California’s precipitation. These changes in sea surface temperatures are referred to as El Niño-Southern Oscillation (ENSO). While strong El Niño conditions are expected to persist into the spring of 2024, past El Niño events have shown significant variation in their impact on California precipitation.

The Public Policy Institute of California published an article on October 16, 2023 by Dr. Xianan Jiang from University of California Los Angeles (UCLA) stating, “Our current climate prediction models have almost no skill in predicting the non-ENSO circulation patterns. This is why the seasonal prediction for California precipitation is so challenging. If we make a prediction based purely on tropical sea surface temperatures, it just won’t be accurate.”

The CAP model brings the missing pieces of the puzzle to the table and provides a complete water year picture. “We believe the CAP report bridges this gap in forecasting,” said Rob Doornbos, owner and founder of Weather Tools. “Our proprietary technique focuses on the requisite atmospheric processes whether they are ENSO-associated or not. This year’s strong El Niño is not a forecast input for us. The Weather Tools CAP forecast methodology takes a deeper dive into unique data sets that no one else is looking at that are foundational to CAP’s impeccable forecast track record,” Doornbos adds.

Each year during the first week of November, Weather Tools, Inc. releases its CAP report, which forecasts the total precipitation for California’s water year from Oct 1^st to Sept 30^th – almost a full year in advance. This statistical model provides two critical pieces of information:

• Whether it will be an “above” or “below” normal water year.
• A definitive range of precipitation amounts, in 20% ranges relative to normal: >40% below normal (BN), 20-40% BN, 0-20% BN, 0-20% above normal (AN), 20-40% AN, or >40% AN.

Once the data is analyzed and predictions are made for the water year, the forecast doesn’t change. Customers are not left chasing a fluctuating prediction and can make informed, water-related decisions months in advance.

In addition to the water year precipitation forecast, customers receive monthly progress reports with information on how the water year is unfolding. This includes an update on precipitation received utilizing National Weather Service data, a meteorological comparison with similar water years, inferences on precipitation patterns and timing, and reservoir status.

“The CAP forecast was a huge benefit to our organization this year both planning budgets and also planning our strategic communications,” said Tim Johnson, CEO of the California Rice Commission. “This tool turned our efforts from a shot in the dark to planning based on actionable information. I can’t recommend it highly enough.”

In California, a precipitation forecast of this type is essential for water management, drought and flood preparedness, reservoir planning, agriculture, renewable power generation, emergency response, and more. The CAP report’s forecast domain includes the footprint covered by the California State Water Project and Central Valley Project contractors and can be further regionalized to meet a customer’s specific operational needs.

Weather Tools has partnered with Baron Weather, to distribute the CAP report. Weather Tools, Inc. is a California-based team with a combined 100 years' experience in Meteorology, data science, and Hydrology. The Weather Tools’ team also includes agriculturalists and farmers, offering a unique blend of talent and perspective into the water challenges facing California.

For more information or to purchase the CAP report: [e-mail], call 1-800-960-7184, or visit www.weathertools.org