PRE-ANALYSIS (per-gauge facts, all timestamps CDT):
| Gauge | First | Max | Last | Intraday Low | Low→peak rise |
|---|---|---|---|---|---|
| Boxley (ft) | 2.64 @00:00 | 2.64 @00:00 | 2.46 @23:30 | 2.46 @22:15 | +0.02 ft (2.54 @13:45 → 2.56 @14:30) — noise-level |
| Ponca (cfs) | 206 @00:00 | 206 @00:00 | 162 @23:30 | 159 @22:30 | none (monotone fall) |
| Pruitt (ft/cfs) | 4.55/360 @00:00 | 4.56/364 @00:15 | 4.31/284 @23:30 | 4.31/284 @23:30 | +0.01 ft only — noise |
| St. Joe (ft/cfs) | 5.14/902 @00:00 | 5.14/902 @00:00 | 4.78/706 @22:45 | 4.78/706 @22:45 | none |
| Harriet (ft/cfs) | 5.06/1180 @00:00 | 5.06/1180 @00:00 | 4.75/917 @22:45 | 4.75/917 @22:45 | none |
| Richland (ft) | 1.21 @00:00 | 1.21 @00:00 | 1.13 @23:00 | 1.13 @23:00 | none |
| Bear Cr (ft/cfs) | 2.19/23.5 @00:00 | 2.19/23.5 @00:00 | 2.15/21.0 | 2.15/21.0 | +0.01 ft (2.15→2.16 @18:30) — noise |
This is a recession-only day (Day ~5–6 of the Event 19 tail) with a trace of sub-threshold rain. Every gauge's max equals its first reading or near it — all are in pure recession from the Day-100 Event 19 peak. No gauge response is attributable to today's rain.
1. PRECIPITATION SUMMARY: Light, spatially-diffuse rain basin-wide. Basin-max 24-hr QPE 0.099" (Pruitt zone), with the wettest individual HUC12s being Flatrock (0.104"), Cove (0.103"), Hoskin (0.095"), Cane Branch (0.080"), Lick Cr (0.077"). Peak 1-hr intensities 0.05–0.078" clustered at 04:02–05:02 CDT (09:02–10:02 UTC). No cell exceeded 0.11" total. This is far below every detection threshold (Boxley ~0.5" wet / ~1.0" dry; Pruitt ~0.3" wet but routing-dominated; St. Joe ~0.3–0.5"). Antecedent is drying (Pruitt-zone 7-day ~2.0–2.6", down from ~2.2–2.8" yesterday).
2. GAUGE RESPONSES: None attributable to rain. All seven gauges fell through the day. Recession rates (cross-event comparison below): - St. Joe: 902 → 706 cfs over 22.75 hr ≈ 8.6 cfs/hr at ~700–900 cfs. - Harriet: 1180 → 917 cfs ≈ 11.6 cfs/hr at ~900–1180 cfs. - Pruitt: 4.55 → 4.31 ft / 360 → 284 cfs. - Ponca: 206 → 162 cfs — crossed below its Low-but-Floatable threshold (200 cfs) at ~01:45 CDT; now sits in Low-but-Floatable (150–200). First mainstem gauge to exit Optimal, exactly as the Day-103 doc predicted. - Boxley: 2.64 → 2.46 ft ≈ 0.0077 ft/hr — slow-seepage pool-drain, ~Day 7, now near/below pre-Event-19 baseline. - Richland: 1.21 → 1.13 ft, flashy decline continuing below pre-event baseline. - Bear Cr: 23.5 → 21.0 cfs ≈ 0.11 cfs/hr — extremely flat flashy tail, no rating-table steps.
3. RAINFALL-RESPONSE PAIRS: None. Peak 1-hr QPE (Pruitt zone 0.078" @ 04:02 CDT) produced no measurable rise at any gauge, so no lag or transfer ratio is computable. This is itself a useful detection-threshold confirmation: ~0.10" zone-max on a drying-but-still-moist antecedent (2.0–2.6" 7-day Pruitt) is fully absorbed — consistent with Open Question #10 (minimum forcing to perturb a flat-recession watershed) and with Event 18's finding that ~0.3" is sub-threshold on a drying antecedent. Today pushes the absorbed-pulse floor lower (~0.10").
4. DOWNSTREAM PROPAGATION: None — no pulse to route.
5. MULTI-DAY EVENTS: Continuation of the Event 19 recession tail (now its 6th tracked recession day). Recreational note: St. Joe (706–902 cfs) and Harriet (917–1180 cfs) remain mid-Optimal; Pruitt (284–364) Optimal; Ponca has dropped to Low-but-Floatable. The Event-19 lower-mainstem Optimal window now extends ≥6 days despite the upstream-only nature of the flood — reinforcing the "attenuated upstream flood still yields a multi-day basin-wide Optimal tail" corollary. Ponca, with the smallest routed reservoir upstream, is first to fall out, as forecast.
6. ANOMALIES OR SURPRISES: None. One quantitative refinement: today extends the dQ/dt-vs-Q recession curve to its low-flow end. We now have St. Joe ~8.6 cfs/hr at ~800 cfs (Day 104) → ~14.5 at ~1100 (Day 103) → ~32 at ~1900 (Day 102); Harriet ~11.6 at ~1050 → 19.3 at ~1250 → 37 at ~1900. The curve remains monotonic and roughly superlinear in Q. Notably St. Joe at ~800 cfs is now falling slower (8.6 cfs/hr) than the Days-95/97 "pipeline-empty" baseline (~10–15 cfs/hr) — the Event-19 pulse has essentially drained and the system is asymptoting toward baseflow; the slope is now baseflow-limited, not interflow-limited.