November 7, 2024
Core Supply Dashboard
WY 2024-25 Precipitation Forecast: 90-110% of normal
Following a slightly below normal water year in 2023-24, California will be looking ‘average’ in water year 2024-25. The California Annual Precipitation (CAP) forecast indicates water year precipitation will be 90-110% of normal.
Expectations for the upcoming water year vary widely, with NOAA’s National Weather Service, media reports, recency bias, and expected La Niña conditions all offering different perspectives (see Insights section). At Weather Tools, we've learned to trust the CAP model and the science behind it, as it has consistently forecasted total water year precipitation accurately in years of extreme abundance and drought- regardless of prevailing expectations.
The dashboard below shows the Core Supply status (Regions 2, 4, and 6).
Core Supply:
CAP Forecast WY 2024-25
Core Supply:
Year-over-Year Comparison
Highlights
- In the CAP data record, weak La Niña years have been associated with varied precipitation patterns: above-normal precipitation occurred twice (in WY 2016-17 with 64.1% and WY 2022-23 with 41.2% above normal) and below-normal precipitation twice (in WY 2017-18 and WY 2021-22, with deficits of 25.8% and 28%, respectively). Despite these varied outcomes, CAP consistently verified in all four instances. Breaking from this dichotomous wet/dry trend, the CAP model indicates that this year's precipitation levels are expected to hover around normal, without significant deviations in either direction.
- Within our eight-year CAP record, water years 2017-18 and 2018-19 bear the most similarities to current conditions. Key model indices align most closely with these years, but with 2017-18 positioned at the lower end with 26% below-normal precipitation, and 2018-19 at the higher end with 28% above-normal precipitation. The current year falls between the two at the normal. We will be closely monitoring these analog years as the season progresses.
