Daily Analysis

Pre-Analysis Per-Gauge Facts (all times CDT; QPE times converted from Z)

Boxley (07055646, height): (a) first 2.34 ft @00:00; (b) max 4.51 ft @08:00; (c) last 3.41 @23:30; (d) intraday low 2.34 @00:00; (e) low→peak +2.17 ft over 8 hr (biphasic: quick pulse 2.65→3.76 @02:45–03:15, dip to 3.53 @05:30, main 4.51 @08:00). Boxley-zone Day-106 1-hr QPE peak 0.394" @07:02Z = 02:02 CDT → peak 4.51 @08:00 = lag 5.97 hr.

Ponca (07055660, discharge): (a) first 264 @00:00; (b) max 1320 cfs @09:45; (c) last 585 @23:30; (d) low 253 @01:30; (e) low→peak +1067 cfs over 8.25 hr. Ponca-zone 1-hr QPE peak 0.462" @07:02Z = 02:02 CDT → peak 09:45 = lag 7.72 hr.

Pruitt (07055680): (a) height first 10.23 @00:00; (b) height max 10.23 ft / discharge max 4290 cfs @00:00 (Event-20 culmination — exceeds yesterday's 10.11/4150 → new study record); (c) last 6.83 ft / 1330 cfs @23:30; (d) intraday low 7.61 ft @03:45 (1850 cfs @03:45–04:00); (e) low→secondary peak 8.90 ft / 2930 cfs @07:00 (+1.29 ft / +1080 cfs) — two-mode signature, plus minor Ponca-routing wobbles at 12:00 (8.12) and 15:00 (8.16).

St. Joe (07056000): (a) first 7.16 ft / 2440 cfs @00:00; (b) max 17.59 ft / 19,600 cfs @08:00 (≈2.45× flood; STUDY RECORD, far above Event 15's 14,500); (c) last 12.22 / 9320 @22:45; (d) low 7.16 @00:00; (e) low→peak +10.43 ft / +17,160 cfs over 8 hr (first sub-peak 10.23 @02:00, dip, main surge to 17.59 @08:00).

Harriet (07056700): (a) first 7.58 / 3990 @00:00; (b) max 17.54 ft @14:30 / 21,800 cfs @13:30–14:00 (≈2.33× flood; STUDY RECORD); (c) last 13.42 / 13,400 @23:45; (d) low 7.34 ft @03:15; (e) low→peak +10.20 ft / +18,120 cfs over ~11 hr (early Bear bump 7.91 @01:15, dip, main propagation surge).

Richland Creek (07055875, height): (a) first 9.13 @00:00; (b) max 9.25 ft @00:15 (Event-20 culmination — exceeds yesterday's 8.35 and Event 15's 8.89 → STUDY RECORD Richland height); (c) last 3.69 @23:00; (d) low 3.69 @23:00; (e) pure flashy recession after overnight peak (noise bump 6.07→6.82 @03:00–05:00).

Bear Creek (07056515): (a) first 10.53 / 11,300 @00:00; (b) max 11.20 ft / 12,900 cfs @01:30 (Event-20 culmination — exceeds yesterday's 8.72/7580 → STUDY RECORD Bear); (c) last 4.03 / 735 @23:15; (d) low 4.03 @23:15; (e) flashy recession with secondary bump 6.14→6.94 ft / 4090 cfs @04:45–06:45.

1. PRECIPITATION SUMMARY

Today's QPE was the trailing pulse of the Event-20 system — light and broadly distributed, basin-max 0.875" (Ponca zone), peaking in the pre-dawn hours (1-hr peaks ~02:02–04:02 CDT). Spatial pattern reversed from yesterday: the upper basin got the most (Boxley 0.781", Ponca 0.875", Pruitt 0.853"), while yesterday's Richland/Bear/Cave bullseye dried to 0.47–0.81". No cell exceeded ~0.55"/hr (Falling Water 0.554"). This rain is a secondary forcing; the day's headline gauge responses are the overnight propagation of Day-105's flood pulse, not today's rain.

2. GAUGE RESPONSES

• St. Joe — study-record trunk flood. 7.16→17.59 ft / 19,600 cfs @08:00, a +10.43 ft / +17,160 cfs surge. This is the Event-20 overnight trunk integration I flagged as pending. First sub-peak 10.23 @02:00 = Richland tributary arrival (Richland peaked 9.25 @00:15 → 1.75 hr Richland→St. Joe); main 17.59 @08:00 = Cave (3.41" D105) + Big (3.36") + Little Buffalo + Richland-outlet integration. Signal separation: Richland surged → trunk surge is Richland-sub-basin + Cave/Big direct, exactly as predicted.
• Harriet — study-record flood. 7.58→17.54 ft / 21,800 cfs @13:30–14:30 (+10.20 ft). Compound source confirmed: early bump @01:15 from Bear Creek confluence (Bear 12,900 cfs @01:30) + main surge from St. Joe propagation.
• Pruitt culminated at 10.23 ft / 4290 cfs @00:00 (record), then two-mode secondary 8.90 ft / 2930 cfs @07:00.
• Boxley delivered the delayed pool-fill: +2.17 ft to 4.51 ft @08:00, crossing Hailstone Optimal (4.4) briefly and above Low-Floatable (3.7) ~03:00–18:00.
• Ponca flashy direct response 253→1320 cfs @09:45 (mid-Optimal, below flood 1600).

3. RAINFALL-RESPONSE PAIRS

Boxley (today's + carried-over rain, primed): zone 0.781" today on top of Day-105's 0.753" (which had only delivered +0.02 ft — held in pool storage). Combined ~1.53" → +2.17 ft = 1.42 ft/in (wet/primed). Lag QPE peak 02:02 CDT → peak 08:00 = 5.97 hr. Antecedent now very wet (Boxley 7-day 3.10"). Comparison: sits in the wet-primed band between Event 4 (1.30, wet-primed) and Event 19 Day-100 (2.28, very-wet+extreme-intensity). Lag 6 hr is faster than the dry pool-fill 7–11 hr (Events 9, 1) — consistent with pool already primed by yesterday. No deviation flag. Confirms local-knowledge pool-and-drop: the 0.753" "filled pools" overnight, then today's pulse rode straight through.

Ponca (today's rain, wet): 0.875" zone → +1067 cfs = 1220 cfs/in. Lag 02:02 → 09:45 = 7.72 hr. Antecedent wet (Ponca 7-day ~2.2–3.1"). Comparison: Event 2 wet ≈1030 cfs/in. Today +18% higher — within tolerance but on the high side; refine wet Ponca range to ~1000–1220 cfs/in.

St. Joe (event-scale, Day-105 tributary forcing): rise from pre-event ~4.5 ft / ~600 cfs to 17.59 / 19,600 = +13.1 ft / +19,000 cfs. Against St. Joe own-zone Day-105 avg 2.16": ~6.1 ft/in (~8,800 cfs/in) — but this is tributary-amplified (Richland 3.79" + Bear inflow not in own-zone QPE). Lag: Cave Cr Day-105 1-hr peak 1.071" @21:02 CDT (Jun 13) → St. Joe peak 08:00 (Jun 14) = ~11 hr. Comparison: exceeds Event 15's wet flood-scale ~4 ft/in and ~3 ft/in event-scale — new study-high St. Joe transfer, driven by simultaneous multi-tributary concentration. This is the highest St. Joe response of the study.

Harriet (event-scale): +10.5 ft / ~+18,000 cfs against Harriet-zone Day-105 2.532" → ~4.1 ft/in (~8,260 cfs/in). Wet flood scale, exceeds Event 15.

4. DOWNSTREAM PROPAGATION

• St. Joe → Harriet: peak 08:00 → 13:30–14:30 = ~6–6.5 hr at flood flow. Straight-line 17.9 km; at sinuosity 1.5 ≈ 26.9 km channel / 6 hr = 4.5 km/hr ≈ 1.24 m/s. Matches Event 15's 6-hr flood timing — confirms the flood-flow lower-mainstem signature.
• Richland → St. Joe (tributary inflow, not cascade): 00:15 → 02:00 first sub-peak = 1.75 hr (reported as tributary arrival, not part of the five-gauge cascade).
• Ponca → Pruitt: today's Ponca peak 09:45 produced only a minor Pruitt wobble ~15:00 (~5.25 hr at high flow); Pruitt was dominated by its own overnight Cove surge, so no clean cascade pair.
• Boxley/Ponca responded in parallel direct forcing (Boxley peak 08:00, Ponca 09:45) — the distributed-forcing signature (Event 11/20 type), not a clean sequential cascade.

5. MULTI-DAY EVENTS

Event 20 is now complete and is the largest event of the study. Day 105 delivered the tributary flood (Pruitt 10.23/4290, Bear 11.20 ft/12,900 cfs, Richland 9.25 ft — all now study records); Day 106 delivered the overnight trunk integration to St. Joe 19,600 cfs (2.45× flood) and Harriet 21,800 cfs (2.33× flood).

This answers Open Q4 (March-2024 signature): the full Event-20 system exceeded the March 2024 reference at St. Joe (17.59 ft / ~13 ft rise here vs 2024's ~15 ft / ~11 ft rise) — and did so from a 3.4–3.9" multi-tributary concentration rather than a single 4–8" Richland bullseye. Conclusion: a 2024-scale (and larger) trunk flood is reproduced when Richland + Cave + Big + Bear flood simultaneously, even at sub-4" totals, because the integrating trunk sums concurrent sub-basin floods.

6. ANOMALIES OR SURPRISES

• Major refinement of the Event-19-vs-20 framing. Yesterday I wrote that lower-basin tributary floods "do not immediately register at the integrating trunk; the trunk surge is delayed." Today shows the delay (~8–11 hr) resolves into a record-breaking trunk flood — fundamentally unlike Event 19 (upper-only forcing, attenuated to 30–36% of flood threshold at the lower mainstem). The lower/mid-basin holds ~52% of basin area (St. Joe own-zone + Richland + Bear + Harriet); concentrated forcing there DOES drive a trunk flood, with an overnight lag. Upper-only does not. This is the clean spatial complement.
• High-stage rating curves performing through study-record stages — St. Joe 17.59 ft / 19,600 cfs and Harriet 17.54 ft / 21,800 cfs tracked smoothly height-vs-discharge.
• Pruitt two-mode confirmed again (surface peak 00:00 + secondary 07:00) — consistent with documented karst/routing behavior, now at flood stage.
• No contradiction to the Bear-Creek stage-dependence finding: Bear's overnight 11.20 ft was the out-of-bank extreme, receding flashily today.