Classification: correct Confidence: Model confidence remains 'low' as only 1 event has been calibrated. This second event further validates the initial hand-seed coefficient. A third successful event will be required to upgrade confidence to 'medium'.
The physics model accurately predicted a negligible stream response (peak error -1.6%) to a minor late-night rainfall event, with the actual peak occurring slightly earlier than predicted due to the rapid response characteristics of the steep Boxley basin.
| Metric | Predicted | Actual | Error |
|---|---|---|---|
| Peak CFS | 31 CFS | 32 CFS | -0 CFS |
| Total rise | — | 2.8 CFS | — |
| Band | Zone | Precip | Predicted Rise | Intensity |
|---|---|---|---|---|
| 1 | boxley | 0.62" | 125 CFS | MODERATE |
The physics prediction was highly accurate in magnitude, forecasting a peak of 31.0 CFS against an actual peak of 31.5 CFS, resulting in a minimal error of -1.6%. The model correctly identified that the 0.625 inches of rainfall, falling largely after midnight, would produce only a trivial rise above the baseflow of ~28.7 CFS. The band contribution calculation of 125 CFS (using the 200 CFS/inch coefficient) was applied correctly to the rainfall input, but the resulting hydrograph peak remained low due to the small absolute volume and the quick recession expected in this steep, small drainage area.
The timing error of approximately 0.4 hours (actual peak at 23:30 CDT, predicted at 04:51 UTC/23:51 CDT) is within acceptable limits for a quiet event. The slight advance in the actual peak time reflects the 'fast response' nature of the Boxley basin (156 km², steep), where runoff concentrates quickly even with low-intensity rain. No calibration adjustments are necessary for the response coefficient, as the magnitude prediction was spot-on. The moisture and intensity multipliers also appear appropriate for this NORMAL/LIGHT-MODERATE event.
No empirical forecast headline was issued today, which is consistent with the lack of significant hydrological activity. The event remains below all Hailstone tier thresholds (low 500 CFS), justifying the absence of a forecast alert. The model's ability to correctly predict a 'quiet day' reinforces its reliability for low-impact events.
No changes made.