Day 67 — Event 9 propagation continues; St. Joe responds strongly. Today is the dry-antecedent calibration event continuation, and it's producing exactly the propagation cascade we hoped to observe.
Trace QPE only today (zone totals 0.02-0.07"). Nothing of hydrologic significance. The Day 66 pulse is the forcing being expressed today.
| Gauge | Day 67 movement | Pattern |
|---|---|---|
| Boxley | 2.77 → 2.60 ft (steady recession from Day 66 peak 3.16) | recession, ~0.04 ft/hr early, slowing |
| Ponca | 313 cfs → 261 cfs | recession from Day 66 peak 396 |
| Pruitt | 4.33 → 4.67 ft peak (02:00) → 4.36 ft | clear delayed peak, +0.65 ft from baseline 4.02 |
| St. Joe | 4.32 → 4.92 ft (still rising at 22:45) | +0.60 ft today, +0.62 ft from baseline; 491→780 cfs (+289 cfs, +59%) |
| Harriet | 4.36 → 4.49 ft (rising in evening) | +0.13 ft, late onset ~22:00 |
| Richland | 1.79 → 1.86 (08:00 peak) → 1.72 ft | secondary minor bump then recession |
| Bear Cr | 2.63 → 2.54 ft / 58.7→47.5 cfs | recession from Day 66 peak |
Pruitt — first clean dry-antecedent ratio: - Pruitt zone QPE Day 66: 0.45" (peak 1-hr 0.28") - Pre-event 4.02 ft / 183 cfs → peak 4.67 ft / 377 cfs at 02:00 Day 67 - Lag from rainfall centroid (~10 CDT Day 66) to peak: ~16 hours (vs ~7 hr expected wet) - Transfer ratio: 0.65 ft / 0.45" = 1.44 ft/in — strikingly close to wet-condition 1.4 ft/in! - Discharge: +194 cfs / 0.45" = ~430 cfs/in - SURPRISE: Pruitt does NOT show the 4× damping seen at Richland and Bear Creek under dry antecedent. Hypothesis: Pruitt zone (Cove Cr, Hoskin Cr) has less karst storage than Bear Creek and the Richland HW zone. Mainstem-fed gauges may behave more like rainfall-runoff response and less like karst-buffered tributaries.
St. Joe — first dry-antecedent ratio (in progress): - St. Joe zone QPE Day 66: 0.72" (peak 1-hr 0.76", max-6hr 1.11" — high intensity) - Adding upstream contribution: Boxley 1.23", Ponca 0.76", Pruitt 0.45" - Drainage-weighted contributing rain across full St. Joe basin (1342 km² + 513 km² upstream): roughly 0.7-0.8" effective - Pre-event 4.41 ft / 530 cfs → 4.92 ft / 780 cfs (still rising) - Current rise: +0.51 ft / +250 cfs against ~0.72" zone QPE - Provisional transfer: ~0.7 ft/in (vs wet ~2.1 ft/in) → ~3× damping — fits dry-antecedent pattern. - Lag: rainfall peak 10:02 UTC Day 66 → St. Joe rise inflection ~10:30 Day 67 = ~22-24 hours, peak still pending Day 68. Wet-condition Pruitt→St. Joe was ~14 hr; dry adds ~8-10 hours. - Significant rise of +0.62 ft confirmed. Discharge +290 cfs and climbing.
Harriet: Just beginning to rise (~22:00). Bear Creek is FALLING during Harriet's rise → consistent with mainstem propagation, not local Bear Creek input. Signal separation working as designed.
Reconstructed timeline from Day 66 morning rainfall peak (~10:00 CDT): - Boxley peak: 12:15 Day 66 (~+2.25 hr) — high-intensity dry, fast - Ponca peak: 15:15 Day 66 (~+5.25 hr; Boxley→Ponca ~3 hr) - Pruitt peak: 02:00 Day 67 (~+16 hr; Ponca→Pruitt ~10.75 hr) - St. Joe rising rapidly Day 67 afternoon-evening; peak likely 04:00-08:00 Day 68 (~+42-46 hr from forcing) - Harriet onset ~22:00 Day 67; peak likely Day 68 evening or Day 69 (~+60+ hr)
Pruitt→St. Joe dry-antecedent lag estimate: ~22-24 hr (vs wet ~14 hr — ~60% slower under dry conditions, consistent with pool-fill / channel storage filling).
Event 9 total magnitudes (so far): - Boxley: +0.87 ft (recovering) - Ponca: +190 cfs peak - Pruitt: +0.65 ft / +194 cfs - St. Joe: +0.62 ft / +290 cfs and rising — discharge nearly 50% above baseline - Harriet: just beginning, +0.13 ft so far - Richland: +0.33 ft (Day 66+67 combined; minor secondary bump from late HUC12 0306 trickle) - Bear Cr: +0.34 ft / +34 cfs (recovered already)
Even with modest 0.7-1.2" zone QPE on dry soils, this single-pulse forcing is generating a measurable Tier-1+ response across the entire mainstem chain.