Pre-analysis per-gauge facts (today, 2026-05-10):
| Gauge | First reading | Max | Last reading |
|---|---|---|---|
| Boxley | 2.26 ft @ 00:00 | 3.09 ft @ 21:45–22:15 | 3.03 ft @ 23:30 |
| Ponca | 190 cfs @ 00:00 | 214 cfs @ 23:30 (still rising) | 214 cfs @ 23:30 |
| Pruitt height | 3.92 ft @ 00:00 | 3.93 ft @ 00:30 | 3.82 ft @ 23:30 |
| Pruitt discharge | 155 cfs @ 00:00 | 158 cfs @ 00:30 | 131 cfs @ 23:30 |
| St. Joe height | 4.10 ft @ 00:00 | 4.12 ft @ 00:30/01:15 etc | 4.02 ft @ 22:45 |
| St. Joe discharge | 401 cfs @ 00:00 | 409 cfs @ 00:30 (early) | 371 cfs @ 22:45 |
| Harriet height | 4.23 ft @ 00:00 | 4.23 ft @ 00:00/00:15 | 4.12 ft @ 22:45 |
| Harriet discharge | 542 cfs @ 00:00 | 542 cfs @ 00:00 | 473 cfs @ 22:45 |
| Richland | 1.36 ft @ 00:00 | 3.24 ft @ 19:45 & 20:15 | 2.95 ft @ 23:00 |
| Bear Creek height | 2.26 ft @ 00:00 | 2.26 ft @ 00:00 | 2.23 ft @ 23:15 |
| Bear Creek discharge | 22.9 cfs @ 00:00 | 22.9 cfs @ 00:00 | 21.0 cfs @ 23:15 |
Significant convective rainfall arrived late afternoon/evening with a strong spatial gradient. Peak 1-hour QPE clustered 19:02–22:02 UTC (i.e., ~14–17 CDT, with most intense cores 14:02–17:02 CDT). Key zones:
Spatial pattern: an arc from the upper headwaters (Boxley/Ponca) sweeping southeast through Richland HW. Pruitt sub-basin in the rain shadow between cores.
Boxley (height-only): Major rise. Trough at 2.20 ft mid-day, then two-stage climb: a small bump to 2.43 ft 17:30–18:00, then the dominant surge — 2.51 ft @ 21:00 → 3.09 ft @ 21:45/22:00, a +0.58 ft jump in 45 minutes (largest hourly rise: +0.63 ft/hr @ 21:45). Recession began 22:30, now 3.03 ft at 23:30. Source: upper Buffalo HW (Terrapin Branch 0201, zone QPE 1.32"). Boxley clearly entered the Low-but-Floatable range for the section above the gauge (≥3.2 ft = Boxley→Ponca floatable; not quite — still under 3.2). Above-Boxley "Hailstone" requires ≥3.7 ft Low-Floatable; not reached.
Ponca (discharge-only): Rising. Trough 178 cfs @ 13:15, then 190 → 214 cfs by 23:30, still climbing. Peak not yet reached today. Source: combined Ponca-zone forcing (Beech 1.30", Smith 1.20") plus Boxley propagation.
Pruitt: No event response. Continued recession from 3.93 → 3.82 ft / 158 → 131 cfs. Pruitt zone QPE only 0.14" — well below detection threshold; the small bumps in the time series (3.86 → 3.88) are within noise.
St. Joe: Mostly in continued recession (4.12 → 4.02 ft, 409 → 371 cfs). Within-day jitter shows a few +0.02 to +0.03 ft micro-rises (17:30, 18:30, 19:00) that hint at early arrival of distributed near-zone runoff from Little Buffalo HW, Big Cr HW, Cave Cr — but no coherent peak yet. The 0.36" zone-avg with concentrated 0.5–0.6" cells in 0102/0302/0305 should produce a delayed rise (~16–36 hr) over coming days.
Harriet: Pure recession. 4.23 → 4.12 ft / 542 → 473 cfs. Harriet zone QPE (0.28") is sub-threshold for direct response; any rise will come from upstream propagation tomorrow.
Richland Creek (FLASH HYDROGRAPH): The major signal. Pre-event 1.33 ft @ ~14:30. Onset of rise 14:45 (1.37). Then explosive climb: - 15:00: 1.40 → 15:45: 1.51 (+0.11/45min, modest first phase) - 16:30: 1.53 → 17:45: 1.81 (+0.28/75min, accelerating) - 18:00: 1.94 → 18:30: 2.93 (+0.99 in 30 min, ~1.98 ft/hr instantaneous) - 18:45: 3.18 ft → 19:45: 3.24 ft peak (held at 3.24 through 20:15) - Recession: 3.24 → 2.95 ft by 23:00 (-0.29 ft / 2.75 hr = -0.10 ft/hr). - Total rise: +1.91 ft in ~5 hr from 1.33 baseline. Largest hourly rise +1.37 ft @ 18:45. - Peak 3.24 ft is just above the 3.2 ft "Low-but-Floatable" threshold for upper Richland recreational use. Brief — already falling back through 3.2 between 21:30 and 22:00.
Bear Creek: No response. 0.33" zone QPE on dry antecedent (7-day Bear Cr HW 1.30", Outlet 0.65" — only modestly wet). Stayed flat 2.23–2.26 ft, 21.0–22.9 cfs. Confirms the ~0.9–1.0" Bear Cr activation threshold; 0.33" is well under.
Richland Creek (high confidence, primary calibration of the day): - Peak 1-hr QPE in 0307: 1.08" @ 20:02 UTC = 15:02 CDT. (Centroid of forcing across 0306+0307 closer to 15:00–16:00 CDT given equal 1-hr peaks.) - Peak gauge: 3.24 ft @ 19:45 CDT. - Lag (peak-to-peak): ~4.5–4.75 hr. Sharper end of dry-condition Richland lag. - Transfer ratio: rise 1.91 ft / zone-avg QPE 1.43" = 1.34 ft/inch. - Antecedent: 7-day Richland zone = 0306: 1.24" / 0307: 1.02", zone-avg ~1.16". This is mid-range moist — not the dry recession floor of Day 65, and not the saturated state of Event 8. Reflects residual moisture from Event 9 (10 days ago) plus Day 70's antecedent.
Cross-event comparison — Richland: | Event | Antecedent | QPE zone | Rise | Lag | Transfer (ft/in) | |-------|-----------|----------|------|-----|------------------| | Event 8 (wet) | very wet | ~3" | ~3 ft | ~6 hr | ~1.0 | | Event 9 (dry) | 6 dry days | 1.04" | 0.33 ft | 22 hr (slow) | 0.25 | | Today (moist) | ~1.16" 7-day | 1.43" | 1.91 ft | ~4.5 hr | 1.34 |
>30% deviation flag: YES. Today's transfer ratio (1.34 ft/in) is higher than wet (1.0) and 5× higher than dry (0.25). The lag is shorter than wet (4.5 vs 6 hr) and dramatically shorter than dry (22 hr). This is a major finding: moderate antecedent (~1.2") + high-intensity (>1 in/hr) forcing produces a more flashy hydrograph than the saturated wet state. Plausible mechanism: karst storage was partially primed by Event 9 residual + Day 70 light rain, so the conduit network activated immediately rather than absorbing the first inch. Once activated, the higher rainfall intensity (1.08"/hr vs ~0.5"/hr typical wet event) produced faster, sharper rise than Event 8's lower-intensity but cumulatively heavier rain. Proposed refinement: add "moist-antecedent + high-intensity" Richland mode to dual-mode table — lag 4–5 hr, transfer ~1.3 ft/in. Note transfer ratio is sensitive to definition: rise/total-QPE = 1.34, but rise/peak-1hr-QPE (1.08") = 1.77, even higher.
Boxley (high confidence): - Peak 1-hr QPE in 0201: 0.67" @ 19:02 UTC = 14:02 CDT. - But Boxley peaks at 21:45 CDT with the surge happening 21:00–21:45 — that's ~7.5 hr from the nominal peak. However, the bulk of rain (max 3-hr 1.07", max 6-hr 1.08") fell 14–17 CDT, suggesting effective forcing centroid ~15:30 CDT. Lag from forcing centroid → peak: ~6.25 hr. - Rise: 2.20 → 3.09 ft = +0.89 ft / 1.32" zone QPE = 0.67 ft/in. - Antecedent: Boxley zone 7-day 1.45" — moist (residual Event 9 + light Day 70). - The 21:45 spike (+0.63 ft in one hour) is classic "pool overtopping" — pre-existing pools filled gradually 17:00–21:00 (+0.23 ft over 4 hr), then crested and released in a near-step rise.
Cross-event comparison — Boxley: - Event 9 dry high-intensity: lag 2.25 hr, transfer 0.71 ft/in (1.23" QPE → +0.87 ft). - Today moist mid-intensity: lag ~6 hr, transfer 0.67 ft/in. - Transfer ratio is near-identical to Event 9 (0.67 vs 0.71 — within 6%). But lag is much longer — 6 hr vs 2.25 hr. Why? Today's peak 1-hr intensity was 0.67" vs Event 9's higher cell, and the total fell over a longer 3–6 hr window. The "pool fill" pattern is visible: gradual rise 17:00–21:00 then step at 21:45. This supports the pool-and-drop local knowledge: under lower-intensity sustained rain on moist (not saturated) antecedent, pools fill slowly and release in a delayed surge. Boxley transfer-ratio coefficient now well-constrained near 0.7 ft/in for dry-to-moist conditions across two events. No >30% deviation in transfer.
Ponca (in progress, low confidence — peak not reached): - 1-hr peak QPE ~14 CDT, Ponca @ 23:30 still climbing (+24 cfs since 13:00 trough). Will likely peak overnight.
Cascade is in progress and incomplete: - Boxley peak ~21:45 CDT. - Ponca: peak not yet reached at end of day 23:30 (still +214 cfs and rising). Expected peak ~01–03 CDT Day 72 based on Boxley→Ponca dry-condition lag of ~3 hr. - Pruitt: no response yet from the Boxley/Ponca surge; expected ~Day 72 morning (using ~10.75 hr dry Boxley→Pruitt sub-segment lag, but partially constrained by very low Pruitt-zone QPE). - St. Joe: not yet — expected late Day 72. - Harriet: not yet — expected Day 73.
Will track tomorrow.
This is the start of Event 10 — a Tier-2 multi-zone event with concentrated Richland forcing and broad upper-watershed activation. Will continue Day 72+. Richland already past peak.