Balanced Ridge forecast inputs
January issuance → April–July · 24m of individual daily gage, weather, and snow histories · four benchmark gages
NMFk extracted signals
Compare the observed-history Ridge control with a balanced observed/CFS kernel. Earlier seasons choose the forecast-block weight and Ridge penalty. Both arms retain identical individual daily histories and the matched 1983–2026 cohort. Annual refitting is tested in 2026 only; weather forecasts cover April–June and discharge targets cover April–July.
Setup and interpretation
All 24 balanced Ridge jobs completed. The blocked 2025–2026 arm selects and fits using labels through 2024 only. Annual 2026 may use earlier 2025 labels for tuning and fitting, never 2026 labels. Each forecast excludes its target-year and later labels. These are retrospective comparisons; reported recent scores must not be used afterward to choose a preferred objective, seed, or configuration.
Observed versus predicted
Errors in the selected period
Each row uses finite observed/predicted pairs from independent forecast years. Positive bias means overprediction. Missing complete truth remains unscored. The displayed range coverage is empirical; nominal coverage is not guaranteed.
Dry, normal, and wet flow errors
Paired objective, refitting, and reference comparisons
Each pair uses identical forecast years with common finite truth and predictions. Negative RMSE change favors the candidate. Keep the recent interval separate from historical comparison. Annual 2026 can tune on earlier 2025 labels under its locked schedule; reported recent scores must not choose a preferred model afterward.
Fixed Ridge seed
This Ridge supplement uses one fixed seed. Seed spread is unavailable and would not provide calibrated forecast uncertainty.