Winter sea level and South Coast precipitation remained linked after linear ENSO adjustment in 1961-2025

We tested the link between winter mean sea level at San Francisco and winter precipitation in the California South Coast division. We used fixed NOAA monthly sources and 62 complete winters in 1961-2025. After removal of a linear time trend, correlation was 0.653. After adding concurrent winter Nino 3.4, it was 0.622, with a 95% five-year block interval of 0.478 to 0.753. Linear ENSO supplied 36.2% of the detrended covariance, but the remaining covariance was positive. The change in correlation was uncertain. Nonlinear ENSO adjustment, omission of three large El Nino winters, ranked responses, and three- and ten-year blocks retained a positive association. Other division and Seattle results give descriptive context. The result shows that this linear ENSO adjustment does not remove the seasonal link. It does not identify a cause or prove independent circulation effects. Selected sites, retrospective products, missing months, and block assumptions limit inference. Seasonal means and totals do not establish same-day floods, water supply, or damage. The package includes source paths and hashes, fixed input fields, code, saved resamples, figures, an independent audit, and an exact repeat.

sea level · precipitation · California · ENSO · compound hazards · partial correlation · block bootstrap