Daily Analysis

Day 59 (April 28, 2026) — Major widespread storm event in progress

1. PRECIPITATION SUMMARY

Today is a Tier 3 candidate event — heavy widespread rainfall across the entire watershed, with a particularly intense convective burst at the close of the day. Total 24-hr QPE exceeds 1.0" zone-averaged in nearly every gauge zone:

• Boxley: 1.379" (peak 1hr 0.825" centered on Terrapin Branch HUC12 0201; 6hr max 1.349")
• Ponca: 1.147" (peak 1hr 0.714"; 6hr max 1.006")
• Pruitt: 1.131" (peak 1hr 0.81"; 6hr max 0.911") — Hoskin Creek 1.312" is the hotspot
• St. Joe: 1.028" (peak 1hr 0.727"; 6hr max 0.953")
• Richland: 1.153" — Falling Water Creek HUC12 0307 received 1.403" with peak 1hr 0.986"
• Bear Creek: 0.921"
• Harriet: 1.059" (peak 1hr 0.957"; 6hr max 1.185") — Spring Creek HUC12 0409 1.255" is hotspot
• Ungauged: 0.685" zone-avg, but Bratton Creek 0507 received 1.174" with peak 1hr 1.016"

HUC12 hotspots (12-hr totals): Henson Creek 1.675", Spring Creek 1.255", Outlet Little Buffalo 1.412", Hoskin 1.312", Falling Water 1.403", Whiteley 1.391", Boxley 1.379". Storm was watershed-wide, with two pulses: one ~13:00 CDT (peak 18:02 UTC = 13:02 CDT) over the lower-mid watershed, and a second very intense pulse late in the day (00:02–01:02 UTC = 19:02–20:02 CDT) loaded into upper headwaters — the Boxley/Ponca/Henson zones.

Antecedent: Already-wet from Event 8 onset and Event 7 recession. Boxley zone 7-day at 2.02", St. Joe headwaters 1.7–2.1", ungauged 2.1–2.5" — the watershed is fully primed.

2. GAUGE RESPONSES

• Richland Creek: Flat at 1.85–1.95 ft most of day, then catastrophic flash response at 20:45 → 21:45 CDT: 1.99 → 4.89 ft (+2.90 ft in 1 hour), peak at 21:45, immediately receding to 4.03 ft by 23:00. This is by far the largest hourly rise we've recorded in the study. Triggered by the 0.986" peak-1hr in Falling Water Creek (HUC12 0307) at 04:02 UTC = late evening CDT.
• Boxley: Flat decline then sharp rise from 18:00 onward: 2.50 → 3.79 ft at 23:30 (+1.29 ft, with +0.75 ft in last 30 min) — still rising at end of day. This is the second-largest Boxley rise of the study.
• Ponca: 173 → 226 cfs (+53 cfs) rising late, still on uptrend.
• Pruitt: Two-pulse response. First pulse: 4.28 → 4.62 ft (+0.34 ft) at 12:30→15:30 CDT. Brief drop to 4.52, then second pulse: 4.52 → 4.73 ft at 21:30 (+0.21 ft). Discharge 252 → 398 cfs (+146 cfs).
• St. Joe: Continued recession most of day (5.04→4.81 ft, 846→722 cfs), but a small upward bump 4.81→4.88 ft at 13:30 CDT (+0.07 ft / +35 cfs) — this is first-pulse arrival from upstream. Currently 722 cfs, rise barely starting.
• Harriet: Began rising mid-afternoon. 4.80 ft (13:15) → 5.06 ft at 20:45 (+0.26 ft, +210 cfs to 1180). Recession continues partial.
• Bear Creek: Minor: 2.30 → 2.36 ft (+0.06 ft, 25.6 → 30.1 cfs). Wet-antecedent threshold marginal — 0.92" total QPE has produced only ~5 cfs of new flow on top of 25 cfs.

3. RAINFALL-RESPONSE PAIRS

Falling Water Creek → Richland Creek (event signature): - QPE: 1.403" total, peak 1hr 0.986" (HUC12 0307), 3-hr max 1.283" - Gauge: +2.90 ft in 60 min - Lag: Peak 1-hr rainfall centered ~03–04 UTC = 22–23 CDT; gauge peak 21:45 CDT. This implies the rise preceded the peak rainfall reading slightly, suggesting the antecedent rainfall buildup (peak 0307 6hr max 1.283") was already running off before the peak hourly rate. Effective lag from rainfall onset to peak rise: ~3–4 hours — extremely fast, characteristic of wet-antecedent runoff in steep tributary terrain. - Transfer ratio: 2.90 ft / ~1.28" effective rainfall = ~2.3 ft/in — far higher than any prior Richland event observed. This is in the range that would correspond to "low but floatable" Upper Richland (3.2 ft) and approaching "optimal" (4 ft). The peak at 4.89 ft briefly hit near-Optimal Upper Richland conditions — a confirmed local-knowledge calibration target. This fits the "3-7 runs/year" guidance. - Comparison to March 4-5, 2024 reference event: That event produced ~17,000 cfs at ~15 ft. Today's 4.89 ft peak is much smaller but the response shape (sub-4-hour flashy spike) matches.

Boxley zone rainfall → Boxley gauge: - QPE: 1.349" 6-hr max in Terrapin Branch (HUC12 0201), peak 1hr 0.825" centered 19:02 CDT - Gauge: 2.50 → 3.79 ft, rising +1.29 ft, with +0.75 ft in final 30 minutes (still in progress) - Lag: Peak rainfall ~19 CDT; first gauge response 18:30 with pool-and-drop signature (pre-peak rainfall response at 18:15→18:30 +0.04 ft); steepening at 23:00–23:30. Lag from QPE peak to current rise rate: ~3-4 hours, consistent with pool-and-drop wet-antecedent acceleration. This is faster than Event 7's ~10.5h lag, matching the local "first major rain after dry spell" hypothesis: pools are full now. - Transfer ratio (in-progress): 1.29 ft / 1.35" = ~0.96 ft/in already, and rising. This will exceed Event 7's 0.78 ft/in. Boxley likely to cross Hailstone "low but floatable" 3.7' threshold (already at 3.79 ft) — second event in the study to do so, but during a still-active rain. Will likely reach "Optimal" 4.4 if rain continues.

Pruitt zone rainfall → Pruitt: 1.13" QPE → +0.36 ft net rise so far. Within expected ratio.

Bear Creek wet-antecedent confirmation: 0.92" QPE on very wet (1.5" 7-day plus residual from Event 8) antecedent → only +0.06 ft and +5 cfs. This contradicts prior hypothesis that Bear Creek wet-antecedent threshold drops to ~0.5". Either the karst threshold is more like 1.0-1.2" even when wet, or peak response is still hours away. Will know tomorrow.

4. DOWNSTREAM PROPAGATION

The first-pulse propagation is now visible: - Pruitt first response 12:45 CDT - St. Joe first bump 13:30 CDT (+45 min lag) - Harriet rising from 13:15 CDT onward

This is much shorter than the typical ~14h Pruitt→Harriet lag and indicates internal-source contribution (Cane Branch, Hoskin, Big Cr-Buffalo all received >1.1") added to Harriet directly — not pure propagation. The Boxley/Ponca pulse is still upstream and will arrive at Pruitt overnight (Day 60 morning) and at St. Joe by Day 60 evening.

5. MULTI-DAY EVENTS

Event 8 has now redefined as a major multi-pulse Tier 3 candidate. Yesterday's lower-watershed pulse produced minor signals; today's two-pulse storm overwhelms the system. Total event QPE (Day 58+59) for some HUC12s now exceeds 2": Henson 1.675", Outlet LB 1.43", Falling Water 1.85" (cumulative). With antecedent 7-day at 1.5–2.5" before today, soil moisture is saturated and additional rainfall will run off near 1:1.

6. ANOMALIES / SURPRISES

• Richland's +2.90 ft in 60 min is unprecedented in the study record and approaches the magnitude (though not the absolute height) of the March 2024 reference event response shape. Prior Richland transfer ratio estimates of ~0.5-1.0 ft/in are blown out by this extreme wet-antecedent flash response.
• Bear Creek remains stubbornly damped even on near-saturated antecedent with 0.92" rainfall — this strengthens the karst hypothesis: Bear Creek may have a structural threshold near 1.5–2.0" before producing a meaningful rise, regardless of antecedent.
• Boxley's pool-and-drop is firing fast because pools are pre-filled by Event 7-8 wetness.
• The rain is still ongoing at the end of Day 59 — Boxley is rising 0.75 ft in 30 min, ungauged hotspots received >1" — Day 60 will be the major analysis day for this event.