No precipitation today. All 37 HUC12s recorded 0.00" for the 24-hour period ending April 20. This is the second consecutive dry day (Apr 19-20). The watershed is now in a post-Event 6 recession with no new rainfall input.
7-day antecedent precipitation remains moderate at 0.77-1.45" across the watershed, with the highest values in Richland headwaters (1.40") and Boxley (1.45"), reflecting the Event 6 Pulse 1 and Pulse 2 contributions from Apr 15-18.
All gauges are in recession. No new rises occurred.
Upper watershed — rapid recession: - Boxley: 2.45 → 2.37 ft (-0.08 ft). Smooth, monotonic decline. Approaching pre-Event 4 baseflow levels (~2.35 ft area). - Ponca: 147 → 136 cfs (-11 cfs, -7.5%). Ponca dropped below 150 cfs ("Low but Floatable" threshold) at ~21:00 Apr 19 and remained below all day Apr 20. Currently at 136 cfs, solidly in "Too Low" territory. This finalizes the Ponca floatable window from Event 4. - Pruitt: 4.09 ft / 203 cfs → 3.97 ft / 169 cfs (-0.12 ft / -34 cfs). Pruitt dropped below 200 cfs (Optimal threshold) around ~02:30 Apr 20 and continued falling. By EOD at 169 cfs, it is in "Low but Floatable" range and declining. Pruitt dropped below "Low but Floatable" (100 cfs) is still far away.
Lower watershed — Event 6 Pulse 2 propagation now visible at Harriet: - St. Joe: Peaked early in the day at 4.38 ft / 495 cfs (~07:00 CST), then began clear recession. By EOD: 4.22 ft / 429 cfs. The Pulse 2 wave has peaked and passed St. Joe. St. Joe Event 6 Pulse 2 peak confirmed: 495 cfs at ~07:00 Apr 20. This is +21 cfs above the EOD Apr 19 value of 474 cfs — a very modest bump, consistent with the small Pulse 2 rainfall totals (0.4-0.7" across the St. Joe zone). - Harriet: Rose through the first half of the day — 516 cfs at midnight to peak of ~594 cfs at ~09:30 (height) / ~18:30 (CFS peak, 594 cfs). The height and CFS data show a broad plateau from ~09:00 to ~18:30 at 4.29-4.31 ft / 581-594 cfs. Harriet Event 6 Pulse 2 peak confirmed: ~594 cfs at ~18:30 Apr 20 (or broad plateau 581-594 from ~09:00-18:30). Rise from pre-pulse trough of ~516 cfs = +78 cfs (+15%). Then began slow recession by late evening: 568 cfs at 23:30.
Signal separation check — Harriet rise source: - Bear Creek: flat at 2.22-2.24 ft / 20.4-21.6 cfs all day. No independent Bear Creek response. - Therefore, the Harriet rise is mainstem propagation from upstream (St. Joe), not independent Bear Creek watershed rain. This is confirmed: Bear Creek flat → Harriet rise = upstream propagation. Consistent with signal separation logic.
Tributary gauges — recession: - Richland: 1.55 → 1.49 ft (-0.06 ft). Continuing steady decline. - Bear Creek: 2.23-2.24 ft, essentially flat at baseflow (~21 cfs).
No new rainfall-response pairs today (no precipitation). However, we can now finalize the Event 6 Pulse 2 propagation timing:
Event 6 Pulse 2 propagation chain (finalized): - Pulse 2 QPE centroid: ~08:00 UTC Apr 18 (~03:00 CST Apr 18) - Boxley peak: 2.63 ft at ~15:30 CST Apr 18 → ~12.5 hr lag - Ponca peak: 173 cfs at ~20:00 CST Apr 18 → ~17 hr lag - Pruitt peak: 232 cfs / 4.20 ft at ~08:00 CST Apr 19 → ~29 hr lag - St. Joe peak: 495 cfs / 4.38 ft at ~07:00 CST Apr 20 → ~52 hr lag - Harriet peak: ~594 cfs / 4.30 ft at ~13:00 CST Apr 20 → ~58 hr lag
These lag times are notably longer than Event 4 Pulse 3 lags (11-40 hr), which is consistent with the lower flow velocities — Event 6 Pulse 2 moved through the system during lower baseflow conditions. The Pruitt-to-St. Joe lag (~23 hr) and St. Joe-to-Harriet lag (~6 hr) are particularly instructive.
Event 6 Pulse 2 peak-to-peak propagation (finalized): - Boxley (15:30 Apr 18) → Ponca (+4.5 hr) → Pruitt (+16.5 hr) → St. Joe (+39.5 hr from Boxley) → Harriet (+45.5 hr from Boxley)
Compared to Event 4 Pulse 3: - Boxley → Ponca: 4.5 hr (E6P2) vs 1.75 hr (E4P3) — 2.6× slower - Boxley → Pruitt: 16.5 hr (E6P2) vs 10 hr (E4P3) — 1.65× slower - Boxley → Harriet: 45.5 hr (E6P2) vs 29 hr (E4P3) — 1.57× slower
The slower propagation is expected given that Event 6 Pulse 2 produced much smaller rises (peak 495 cfs at St. Joe vs 2,630 cfs for Event 4) and thus lower channel velocities.
Event 6 is now COMPLETE. Both pulses have propagated through all gauges and all gauges are in recession.
Finalized Event 6 summary: - Pulse 1 (Apr 15-16): Concentrated Richland/Cave Creek zone. Direct response at St. Joe (+146 cfs to 437 cfs peak Apr 18 ~07:15). - Pulse 2 (Apr 18): Widespread 0.3-0.7". Upper/middle watershed concentrated. Propagated through entire chain. - St. Joe composite peak: 495 cfs at ~07:00 Apr 20 (from Pulse 1 tail + Pulse 2 propagation overlap). - Harriet composite peak: 594 cfs at ~13:00-18:30 Apr 20. - Total St. Joe rise from Event 6: 291 cfs → 495 cfs = +204 cfs (+70%) - Total Harriet rise from Event 6: 396 cfs → 594 cfs = +198 cfs (+50%)
Recreational duration tracking — finalized for Events 4+6 combined:
| Gauge | Threshold | Entered | Exited | Duration |
|---|---|---|---|---|
| Ponca (>150 cfs) | Low-but-Floatable | ~11:00 Apr 4 | ~21:00 Apr 19 | ~15.4 days |
| Pruitt (>200 cfs) | Optimal | ~09:00 Apr 4 | ~02:30 Apr 20 | ~16.7 days (with brief dips in/out near boundary Apr 17-18) |
| St. Joe (>200 cfs) | Optimal | ~12:00 Apr 4 | Still above — 429 cfs EOD Apr 20 | 16.5+ days and counting |
| Harriet (>200 cfs) | Optimal | ~18:00 Apr 4 | Still above — 568 cfs EOD Apr 20 | 16.1+ days and counting |
Revised projections for St. Joe and Harriet exit from Optimal: - St. Joe: Currently 429 cfs, declining ~65 cfs/day. At this rate, drops below 200 cfs around Apr 23-24. However, recession rates typically slow as flow decreases, so more likely Apr 25-27. Revised projection: ~21-23 days total Optimal duration. - Harriet: Currently 568 cfs. Even after the Event 6 Pulse 2 peak passes, Harriet's larger drainage basin sustains flow longer. Projection: drops below 200 cfs around Apr 27-30. Revised projection: ~23-26 days total Optimal duration.
Harriet's surprisingly sustained rise. The Harriet gauge rose from ~516 cfs to ~594 cfs (+78 cfs, +15%) today despite zero precipitation, purely from upstream propagation of Event 6 Pulse 2. Bear Creek flat confirms this is entirely mainstem-sourced. The broad plateau (581-594 cfs from ~09:00 to 18:30) lasting ~9.5 hours suggests the Pulse 2 wave arriving at Harriet was significantly attenuated and spread out — a flattened, broad wave rather than a sharp peak. This is characteristic of small events propagating through large drainage basins.
Ponca-Pruitt baseflow divergence continues. At EOD: Ponca 136 cfs (drainage 390 km²) vs Pruitt 169 cfs (drainage 513 km²). Pruitt's discharge is only 24% higher despite 32% more drainage area. The Ponca value seems proportionally low, potentially consistent with the known scouring issue affecting the Pruitt gauge at low flows (local knowledge: more flow on river right away from gauge) — though in this case it's Ponca that seems low. The Ponca gauge has only discharge (no height), so we can't cross-check with height data. This discrepancy may reflect rating curve issues at Ponca during low flow.