Classification: false_negative Confidence: Band 1 confidence remains medium due to frequent discrepancies between QPE and gauge observations during sharp rises. Bands 4-5 are moving toward high confidence as they are being adjusted for wet-soil performance.
The model severely underestimated a sharp 1.62 ft rise driven by unmeasured near-gauge rainfall, predicting only 0.03 ft while ignoring significant QPE in headwaters bands that likely contributed to the broad background rise.
| Metric | Predicted | Actual | Error |
|---|---|---|---|
| Peak height | 3.87 ft | 4.58 ft | -0.71 ft |
| Total rise | — | 1.62 ft | — |
| Band | Precip | Predicted Rise | Intensity | Moisture |
|---|---|---|---|---|
| 5 | 0.09" | 0.03 ft | LIGHT | WET |
Headline: Watch — Recent rainfall is in the lower-bound range preceding rises to LOW Settled outcome: missed_higher (reached medium) LLM said headline was correct: False Notes: The empirical model predicted 'Low' tier (Watch) but the actual peak reached 'Medium' tier (4.58 ft > 3.4 ft threshold). This is a missed higher outcome.
The prediction engine generated a peak of 3.87 ft, missing the actual peak of 4.58 ft by 0.71 ft (-15.5%). While this error margin is borderline for 'correct' classification in isolation, the mechanism of failure is critical. The model predicted almost exclusively from Band 5 (0.09"), ignoring substantial rainfall in Bands 3, 4, and 5 (accumulating >0.2" per band). More importantly, the hydrograph was 'sharp' with a rise duration of only 0.2 hours and no measurable precipitation at the gauge. This signature strongly indicates a burst of unmeasured near-gauge rainfall (Band 1), similar to Event 3 or the anomalies noted in previous Band 1 updates. The model's failure to account for this implicit Band 1 input, combined with its neglect of the visible headwaters rain, constitutes a functional false negative regarding the event's true drivers and magnitude.
The timing error of 10.1 hours (predicted peak next day vs actual peak same day afternoon) further confirms the model misidentified the source. A 10-hour lag implies headwaters-only response; a sharp, immediate rise implies near-gauge response. The model effectively ignored the dominant signal. The empirical forecast also failed, predicting 'Low' tier when 'Medium' was reached, compounding the missed opportunity for alerting.
Given the sharp hydrograph shape and zero gauge rain, Band 1 must be assumed to have carried the primary load despite QPE silence. The coefficient for Band 1 should be increased to account for this 'invisible' rainfall driver. Conversely, Bands 2-4 showed QPE but contributed less than expected given the wet soil conditions, or their contribution was masked/offset by the Band 1 burst timing. However, since Band 1 is the most likely culprit for the sharp rise, we prioritize adjusting Band 1. We will also slightly increase Band 4 and 5 as they had significant QPE on wet soil that was largely ignored in the prediction.
| Band | Change | Reason |
|---|---|---|
| 1 | +15% | Sharp rise with 0" gauge rain indicates unmeasured near-gauge burst. Model ignored this likely driver. Increasing Band 1 sensitivity to capture future 'invisible' near-gauge events. |
| 2 | -10% | Band 2 QPE (0.21") did not correlate with a significant distinct rise component; the rise was too sharp for Band 2 lag. Penalizing for lack of distinct contribution. |
| 3 | +5% | Moderate QPE (0.63") on WET soil should have contributed more to the base rise. Small increase to account for wet-soil efficiency in headwaters. |
| 4 | +10% | Significant QPE (0.93") on WET soil was largely ignored by the prediction. Wet soils amplify headwaters response. Increasing coefficient to better reflect wet-condition runoff. |
| 5 | +10% | Band 5 had QPE (0.89") but was the only band the model 'saw'. It predicted too little rise from it. Increasing to better capture headwaters contribution on wet soil. |
Band 1 confidence remains medium due to frequent discrepancies between QPE and gauge observations during sharp rises. Bands 4-5 are moving toward high confidence as they are being adjusted for wet-soil performance.