End of long dry spell — Event 7 begins. After 6 days of recession (last rain Apr 18), a major widespread rainfall event began this morning and is still in progress at end-of-day Apr 24.
Watershed-wide event with peak intensities clustered in mid-morning CDT (10-11 UTC = ~05-06 CDT, with secondary intensification through 11 UTC = 06 CDT — note times listed as 11:02 UTC = 06:02 CDT).
Zone totals (24-hr): - Pruitt: 1.353" (peak Cove Creek 1.343", Hoskin Creek 1.362", Flatrock 1.403") - Boxley: 1.249" (single HUC12, peak 1-hr 0.697") - Ponca: 1.247" (Beech 1.215", Smith 1.226", Whiteley 1.300") - Harriet: 1.237" but heavily weighted to Water Creek 1.486" and Tomahawk 1.374" — peak 1-hr 0.846" at Water Creek - St. Joe: 1.061" zone average — Big Creek complex 1.0-1.1", Little Buffalo 1.07-1.21", Cave Creek lighter at 0.871" - Richland: 0.984" (Headwaters 1.054", Falling Water 0.913") - Bear Creek: 0.901" (lightest of all gauged zones) - Ungauged below Harriet: 1.31" with peaks Clabber Creek 1.60", Rush Creek 1.575"
Spatial pattern: Watershed-wide but with two intensity maxima: (1) upper watershed (Boxley/Ponca/Pruitt) and (2) Harriet direct + downstream ungauged zone. Big Creek and Cave Creek somewhat lighter than rim. Peak hour was 11:02-12:02 UTC across most HUC12s — a fairly synchronous event.
Antecedent: 7-day totals at start of day were 0.3-0.7" (relatively low after 6-day dry spell). Watershed had drained substantially — Boxley near baseflow, all gauges at lowest values since early March.
| Gauge | Pre-Event (00:00) | EOD value | Rise so far | Trajectory |
|---|---|---|---|---|
| Boxley | 2.19 ft | 3.01 ft (peaked 3.21 ft @ 16:30) | +1.02 ft (peak +1.02 ft) | Past peak, falling |
| Ponca | 115 cfs | 300 cfs (peaked 347 @ 18:15) | +232 cfs peak | Past peak, falling |
| Pruitt | 119 cfs | 527 cfs / 5.08 ft | +408 cfs / +1.34 ft | Still rising rapidly |
| St. Joe | 295 cfs | 356 cfs | +69 cfs | Slow rise, early phase |
| Harriet | 385 cfs | 594 cfs / 4.31 ft | +209 cfs / +0.34 ft | Still rising |
| Richland | 1.32 ft | 2.35 ft (peaked 2.50 @ 17:15) | +1.18 ft peak | Past peak, falling |
| Bear Creek | 2.17 ft / 17.5 cfs | 2.20 ft / 19.2 cfs | +0.03 ft / +1.7 cfs | Minimal — confirms zone-light response |
Boxley response timing: Rapid jump from 2.18→2.23 ft between 05:00-05:15 — that's a 0.05 ft step in 15 min suggesting localized convective onset. Then steady climb to 3.21 ft peak at 16:30. Crossed 3.2 ft (Boxley-Ponca section "Low but Floatable" threshold) at ~15:15, peaked just at 3.21 — barely entered floatable range, consistent with local knowledge that this section rarely runs.
Pruitt rapid rise: Pruitt has gone 3.74→5.08 in 22 hours and is still rising. Rate accelerating after 19:00 (433→527 cfs in last 4 hours). Will likely peak overnight Apr 25.
Boxley pair: 1.249" zone QPE (peak intensity ~10-11 UTC = 05-06 CDT) → peak height 3.21 ft at 16:30 CDT, ~10-11 hr lag from peak rainfall. Rise 1.02 ft per 1.25" rain = transfer ratio ~0.82 ft/in. Antecedent was dry (0.61" 7-day) — consistent with prior observations that dry antecedent dampens initial response. Compare to Event 4 Pulse 3: 1.57" produced +2.05 ft (1.30 ft/in) on moderate antecedent. Lower transfer today aligns with lower antecedent moisture.
Richland pair: 0.984" zone QPE → +1.18 ft at 17:15. Transfer ~1.20 ft/in on dry antecedent (0.78" 7-day). Did NOT cross 3.2 ft (upper Richland Low-Floatable threshold) — peaked at 2.50 ft. This sub-1" event is below the threshold for a Richland run, as expected.
Pruitt pair (preliminary, still rising): 1.353" → +1.34 ft so far / 5.08 ft. Transfer already ~1.0 ft/in and climbing. With Pruitt still rising and likely to peak ~5.5-6.0 ft based on Boxley/Ponca propagation, final transfer ratio likely 1.4-1.6 ft/in. Crossed 200 cfs Optimal at ~12:30 CDT.
Ponca pair: 1.247" → +232 cfs peak (115→347). On low-flow antecedent. Crossed 200 cfs Optimal threshold at ~10:45 CDT. Lag from peak rainfall (~05-06 CDT) to gauge peak (~18:15 CDT) ≈ 12-13 hours.
Harriet pair (still rising): 1.237" zone with concentrated rain in direct zone (Water Creek 1.486", Tomahawk 1.374") → +0.34 ft / +209 cfs so far. Bear Creek essentially flat (+1.7 cfs), so this rise is direct rainfall on Harriet sub-basin, not propagation. Initial pulse arrived ~06:15 CDT (369→396 cfs jump) — only ~25-30 min after upper-watershed peak rainfall, suggesting rapid local response from Water/Tomahawk Creeks rather than Bear Creek.
Boxley peak 16:30 → Ponca peak 18:15 = ~1.75 hr. Faster than Event 1 (4-5 hr) and consistent with Event 3 timing — moderate flow velocities. Pruitt still rising at 23:30 — propagation into Pruitt likely occurring now. St. Joe and Harriet have not yet seen the upstream propagation wave; their rises so far are direct rainfall on their own sub-basins. The big upstream propagation pulse will arrive at St. Joe Apr 25 evening and Harriet Apr 26.
This is Day 1 of a new event. Rain is essentially over (peaked late morning, tapering). Major downstream propagation will play out Apr 25-26. St. Joe and Harriet rises so far are local-only; both will see substantial additional rises when the upstream wave arrives.