Pre-analysis per-gauge facts (today, 2026-05-18): - Boxley: first 1.88 ft @ 00:00 → max 1.89 ft @ 00:15/00:45/01:00/01:15/01:45 → last 1.84 ft @ 23:30. Pure recession, slight overnight noise. - Ponca: first 75.2 cfs @ 00:00 → max 75.2 cfs (multiple early) → last 70.8 cfs @ 23:30. Pure recession. - Pruitt: first height 3.51 ft / 69.0 cfs @ 00:00 → max height 3.52 ft @ several early times / max cfs 70.7 @ 00:15 → last 3.45 ft / 59.6 cfs @ 23:30. Recession with no event-scale rebound despite afternoon QPE. - St. Joe: first height 3.54 ft / 216 cfs @ 00:00 → max height 3.55 ft @ 01:15, 01:45, 02:15, 02:30, 06:30 / max cfs 219 @ 01:15, 01:45, 02:15, 02:30, 06:30 → last 3.48 ft / 198 cfs @ 22:45. Recession with minor noise; peak is essentially the first reading. - Harriet: first height 3.74 ft / 265 cfs @ 00:00 → max height 3.74 ft @ 00:00–00:30 / max cfs 265 @ 00:00–00:30 → last 3.68 ft / 237 cfs @ 22:45. Pure recession. - Richland: first 1.24 ft @ 00:00 → max 1.24 ft (revisited 10:00–11:30, 13:00–15:45 multiple times) → last 1.22 ft @ 23:00. Notable: Richland rose from intraday low of 1.21 ft (08:00–09:15) back to 1.24 ft by 11:00 — a +0.03 ft micro-pulse coinciding with the heaviest QPE hour. - Bear Cr: first 2.08 ft / 13.2 cfs @ 00:00 → max 2.08 ft @ multiple / max cfs 13.2 at multiple → last 2.06 ft / 12.4 cfs @ 23:15. Slow recession; intraday bumps from 2.06→2.08 around 11:30–14:30 align with QPE timing but stay within noise band.
First measurable QPE in 9 days. Convective cells concentrated in afternoon (15–16 CDT peaks). Spatial pattern is strongly southern/southeastern:
The heaviest core (1-hr 0.273" Long Creek) is outside the gauged network entirely. Within gauged zones, the Big Creek complex and Headwaters Richland (0306) saw the strongest 1-hr intensities. Antecedent was extremely dry (7-day prior to today's event: 0.04–0.18" range across all zones — essentially recovered baseflow regime from Day 78).
No gauge produced an event-scale rise. All gauges remained in their multi-day recession trajectory through the event. Specifics:
Only one rainfall-response pair is identifiable:
Richland micro-pulse: zone QPE 0.182", 1-hr peak 0.199" @ ~10:02 CDT (HUC12 0306). Gauge low 1.21 ft @ 08:00–09:15, peak 1.24 ft @ 11:00. Rise = +0.03 ft. Lag = ~1 hr from 1-hr peak (0306 is the upstream sub-basin; flashy Richland response well-known). Transfer ratio = 0.03 ft / 0.182" = 0.16 ft/in.
Non-detection contrasts (informative): - Boxley: 0.128" zone QPE, 1-hr 0.059", produced zero rise (continued to fall). This is a clean non-detection at the dry-antecedent detection threshold. Combined with the Day 78 dry-baseline + the local-knowledge "pool-and-drop fills first" observation, this confirms that ~0.13" in 1-hr is below the Boxley dry-antecedent detection threshold. - Big Creek complex (St. Joe sub-group): 0.350" Left Fork Big Cr / 0.250" Headwaters Big Cr (each ~the heaviest gauged sub-basin total today) produced no visible St. Joe peak. The St. Joe response should arrive late tomorrow if it materializes — this is a key Tier-1 detection-threshold watch. - Bear Cr: 0.122" Headwaters Bear Cr / 0.099" Outlet — no detectable rise. Matches D77 non-detection pattern at similar zone QPE.
No propagation today — no mainstem peaks to chain together. All mainstem gauges in continuing recession from the May 10–14 Event 10 cascade.
Recession from Event 10 continues uninterrupted. Today's QPE was insufficient to perturb the asymptotic decay trajectory at any mainstem gauge. New study-period lows recorded at every gauge — the basin is now at its deepest baseflow state of the 90-day study.
Comparing to Day 78 recession rates: - St. Joe Day 79: 216 → 198 cfs over ~23 hr = -0.78 cfs/hr. Sequence: D75 -3.1 → D76 ~2.0 → D77 ~1.5 → D78 -1.1 → D79 -0.78 cfs/hr. Geometric decay continues; ratio D79/D78 ≈ 0.71, consistent with prior ~0.7 daily decay ratio. - Harriet Day 79: 265 → 237 cfs = -1.22 cfs/hr. Sequence: D78 -1.5 → D79 -1.22 cfs/hr. - Pruitt Day 79: 69.0 → 59.6 cfs = -0.41 cfs/hr. (Pruitt now 17 cfs below Day 78 close — Pruitt continues steeper proportional decline than St. Joe / Harriet.)
Big Creek complex watch: Day 80 (tomorrow) is the key observation window for whether the 0.35"/0.25" Big Creek QPE produces a delayed sub-detection or detectable rise at St. Joe. Based on Event 10's Pruitt→St. Joe lag of 23 hr at moderate flow and the lower-flow regime today, expect peak arrival ~24–36 hr post-rainfall (≈D80 12:00–D81 00:00) if any rise occurs. Given that 0.13" Boxley produced nothing and that Richland's response was 0.03 ft, I expect St. Joe to show at most a few cfs noise; my prediction is non-detection.
Day 77 → Day 79 spatial pattern continuity: This is the second sub-threshold event in 3 days where rainfall concentrated in the southeastern part of the watershed (Day 77 lower-watershed scatter; today Big Creek/Richland/ungauged). The Boxley/Ponca/Pruitt corridor has now been essentially dry for ~10 days while the southeast has received 3 modest pulses. This may set up a spatial decoupling test if a larger event hits one side: zone-specific antecedent now diverges meaningfully (Boxley zone 7-day 0.06" vs. ungauged Long Creek zone 0.18"–0.40" by tomorrow morning).
Bear Creek baseflow decoupling hypothesis (from D78) — no new confirming evidence today. Bear Cr received another 0.111" today but height held roughly steady at 2.06–2.08 ft (vs. continuing fall expected). Discharge dropped only 13.2 → 12.4 cfs. The pattern is consistent with subsurface support from sub-threshold rain, but the signal is too small to confirm independently. Confidence remains medium.
Pruitt dropped to 3.43 ft / 56.6 cfs, now well below the "Too Low" recreational threshold of 100 cfs and continuing to fall. Per the local-knowledge note about scour shifting flow to river-right at low stage, Pruitt CFS values likely under-represent real flow at this stage. The Pruitt-vs-Ponca comparison is increasingly unreliable.