Pre-analysis per-gauge facts (Day 73, 2026-05-12): - Boxley (07055646): first 2.52 ft @ 00:00; max 2.52 ft @ 00:00 (= first reading, pure recession); last 2.35 ft @ 23:30. Range -0.17 ft. - Ponca (07055660): first 239 cfs @ 00:00; max 239 cfs @ 00:00 (= first reading, pure recession); last 203 cfs @ 23:30. Range -36 cfs. - Pruitt (07055680): first height 4.23 ft @ 00:00, first discharge 240 cfs @ 00:00; max height 4.24 ft @ 00:45, max discharge 243 cfs @ 00:45 (small early-day blip); last 3.98 ft / 171 cfs @ 23:30. Range -0.26 ft / -72 cfs. - St. Joe (07056000): first 4.44 ft / 543 cfs @ 00:00; max 4.53 ft @ 13:15–14:00 / 584 cfs @ 13:15; last 4.40 ft / 525 cfs @ 22:45. Within-day rise of +0.16 ft / +41 cfs from morning trough (4.37 ft / 512 cfs @ ~06:15–08:00) to mid-day peak. - Harriet (07056700): first 4.45 ft / 691 cfs @ 00:00; max 4.48 ft / 712 cfs @ 03:00; last 4.38 ft / 642 cfs @ 22:45. Continued Event 10 propagation peak then receded; renewed gentle rise late day (4.33 → 4.38 ft from 16:30 → 22:45). - Richland Creek (07055875): first 2.18 ft @ 00:00; max 2.19 ft @ 00:15 (= near first reading); last 1.91 ft @ 23:00. Pure recession, range -0.28 ft. - Bear Creek (07056515): first 2.22 ft / 20.4 cfs; max 2.23 ft / 21.0 cfs @ 11:45 (single-step noise blip); last 2.21 ft / 19.8 cfs @ 23:15. Effectively flat.
Zero rainfall across the entire watershed. All 37 HUC12s record 0.000" 24-hr QPE. 7-day antecedents are essentially unchanged from D-1 (tiny upticks of <0.05" reflect rounding/light residual). Boxley zone 7-day stands at 2.78", Richland 7-day at 2.55–2.61" — both peak values driven entirely by the Day 71 convective event.
With no forcing today, all activity is Event 10 propagation/recession:
Today produced no QPE, so no new direct rainfall-response pairs. But Event 10 cascade reaches completion today, enabling the Harriet Event 10 transfer ratio that was pending Day 72:
Harriet Event 10: - Peak: 4.48 ft / 712 cfs @ D73 03:00 - Pre-event: 4.12 ft / 473 cfs (D71) - Rise: +0.36 ft / +239 cfs - Direct QPE for Harriet zone: 0.28" - But Harriet response is dominated by mainstem propagation, not local QPE. Compute against upstream St. Joe input: St. Joe rose +282 cfs; Harriet rose +239 cfs ≈ 85% of St. Joe rise propagated downstream. - Per-inch transfer (using direct Harriet zone QPE only, with the caveat that propagation dominates): 239 cfs / 0.28" = 854 cfs/in — clearly an over-estimate because Harriet's rise is mostly NOT from local rain. More meaningful: 0.36 ft / 0.28" = 1.29 ft/in, but again propagation-dominated. - St. Joe peak → Harriet peak lag = 14.5 hr (D72 12:30 → D73 03:00). - Cross-event comparison: Event 8 (saturated antecedent) St. Joe→Harriet lag was shorter and Harriet rose more strongly relative to St. Joe; Event 10 antecedent at Harriet was 0.33" (dry to moderate) vs Boxley/Richland zones which were moist-mid (1.0–1.5"). The 14.5-hr St. Joe→Harriet lag falls within prior expectations for moderate-flow propagation. Antecedent at Harriet was DRIER than at upstream zones, so transfer attenuation (Harriet rise = 85% of St. Joe rise) is consistent with channel absorption in the relatively dry Harriet local watershed.
Pruitt Event 10 secondary signal arriving at St. Joe (Day 73 13:15 secondary peak): - Pruitt peak D72 14:00 (287 cfs) - St. Joe secondary peak D73 13:15 (584 cfs, +72 cfs above morning trough) - Pruitt → St. Joe lag for mainstem signal: ~23.25 hr in low-mid flow conditions - This is consistent with the prior-event observation that mainstem-only Pruitt→St. Joe routing is slow in low flow; the Richland tributary signal arrives much earlier (Richland peak D71 19:45 → St. Joe primary peak D72 12:30 = 16.75 hr). - Confidence: moderate. The 584 cfs reading at 13:15 could partly be noise, but the smooth rising curve from 512 cfs (08:00) → 584 cfs (13:15) over 5+ hours indicates a real signal.
Mainstem-only chain for Event 10 final cascade (mainstem gauges only, per role instructions): - Boxley peak: D71 21:45 - Ponca peak: D72 01:45 (4.0 hr from Boxley) - Pruitt peak: D72 14:00 (12.25 hr from Ponca) - St. Joe primary peak: D72 12:30 (from Richland tributary, NOT mainstem propagation — flagged for context but excluded from mainstem velocity calc) - St. Joe secondary/mainstem peak: D73 13:15 (23.25 hr from Pruitt — this IS the mainstem signal) - Harriet primary peak: D73 03:00 (14.5 hr from St. Joe primary D72 12:30 — Richland-driven cascade) - Harriet secondary rise: pending (still rising 22:45)
Mainstem-only routing velocity: Boxley→Ponca→Pruitt→St. Joe(secondary): ~39.5 hr cumulative for the slow mainstem signal in low-mid flow. Boxley→Pruitt = 16.25 hr (very slow in low flow), Pruitt→St. Joe(mainstem) = 23.25 hr. These low-flow velocities are consistent with the long Day 72 Ponca→Pruitt time we already flagged.
Event 10 effectively complete at Harriet. Total Event 10 timeline: - Forcing: D71 14–17 CDT - Boxley peak: D71 21:45 - Cascade duration to Harriet primary peak: D71 ~16:00 → D73 03:00 = ~59 hr forcing-to-Harriet-peak - Secondary mainstem signal still arriving at Harriet end of D73. - Total event magnitudes: Boxley +0.89 ft; Richland +1.91 ft; Ponca +164 cfs; Pruitt +156 cfs; St. Joe +282 cfs (primary), +72 cfs (secondary); Harriet +239 cfs.
MAJOR FINDING: The St. Joe double-peak structure is now empirically resolved. The hypothesis document already stated that "St. Joe peak (D72 12:30) preceded Pruitt peak (D72 14:00) by 1.5 hr" demonstrating Richland-tributary dominance. Today extends that finding: the Pruitt mainstem signal arrives at St. Joe ~23 hours LATER as a distinct secondary peak. This is the first explicit observation of double-peak structure at St. Joe attributable to differential tributary-vs-mainstem timing. Strongly validates the signal-separation framework and gives a quantitative Pruitt→St. Joe low-flow mainstem lag (~23 hr).
The Harriet late-day re-rise (16:30 → 22:45, +0.05 ft / +34 cfs) is the leading edge of the secondary signal propagating from St. Joe. Confirm tomorrow.