A moderate, widespread rain event occurred on April 18, centered in the morning hours (peak ~03:00-06:00 CST / 08:00-11:00 UTC). This is a continuation and amplification of Event 6 rainfall.
Spatial pattern — upper/middle watershed concentrated: - Pruitt zone: Hoskin Creek 0.689" (0.376"/hr peak), Cove Creek 0.518" — zone avg 0.603" - Ponca zone: Smith Creek 0.718" (0.300"/hr), Whiteley Creek 0.586", Beech Creek 0.538" — zone avg 0.614" - Boxley: 0.605" (0.216"/hr) - St. Joe zone: Flatrock Creek 0.666", Henson Creek 0.699" (0.352"/hr), Outlet LB 0.592", Shop Creek 0.432" — zone avg 0.464" - Little Buffalo complex: 0.432-0.699" (avg ~0.583") - Big Creek complex: 0.364-0.426" (avg ~0.386") - Cave Creek: 0.388" - Richland zone: Headwaters Richland 0.441", Falling Water 0.339" — zone avg 0.390" - Bear Creek zone: 0.423" (Headwaters 0.430", Outlet 0.417") - Harriet zone: 0.351-0.444" — zone avg 0.374"
All rain fell in a ~6-hour window; peak intensities were moderate (0.1-0.38"/hr). This is essentially a second pulse of Event 6, arriving 2 days after the first.
Event 6 propagation from Apr 15-16 rainfall dominates the lower gauges today, with today's new rainfall adding a second pulse to upper gauges.
Boxley (07055646): Rose from 2.42 ft at 01:00 to 2.63 ft at 15:15-18:00 CST (+0.21 ft). This is a clear response to today's 0.605" local rain. Rise began ~04:45 CST, consistent with rain starting ~03:00 CST (08:00 UTC). Peak is modest — Tier 1 detection level.
Ponca (07055660): Rose from 139 cfs at 02:00 to 173 cfs at 19:45-20:30 CST (+34 cfs, +24%). Still below "Low but Floatable" threshold of 150 cfs for much of the morning, crossing back above 150 cfs around ~12:45 CST. The rise is a combination of Boxley propagation and direct Ponca-zone rainfall (0.614").
Pruitt (07055680): Small bump at 02:45-03:30 CST (+0.06 ft, from 4.01 to 4.08 ft). This is the tail of Event 6 Pulse 1 propagation arriving. Then a gradual decline through the day (4.08 → 4.01 by 16:00), followed by a slight uptick to 4.06 by end of day. CFS range: 180-200, hovering in "Low but Floatable" zone. The early morning bump peaked at exactly 200 cfs (Optimal threshold) at 03:30 and 05:15-05:45, but didn't sustain it.
St. Joe (07056000): Continued rising as predicted. Rose from 3.85 ft / 291 cfs (Apr 17 00:00) through 4.09 ft / 379 cfs (Apr 17 EOD) and continued to 4.24 ft / 437 cfs peak today around 07:15-09:30 CST. Total rise from Event 6: +0.40 ft / +146 cfs from pre-event baseline (3.84 ft / 291 cfs on Apr 16). The peak at 437 cfs is within my predicted range of 400-450 cfs from Day 48 analysis. St. Joe appears to have peaked or is near peak — slight decline visible from ~10:00 onward (437 → 413 cfs by EOD), though still elevated.
Signal separation at St. Joe: Richland gauge rose only 0.11 ft today (1.59→1.70, peaking ~10:15), a modest response to 0.39" local rain. This is consistent with the St. Joe rise being driven primarily by mainstem propagation from upstream (Event 6 Pulse 1 + today's upper watershed rain working through the system), supplemented by distributed rainfall across the St. Joe sub-basin. The Richland rise does not account for the magnitude of the St. Joe increase.
Harriet (07056700): Strong, sustained rise all day. Rose from 4.01 ft / 408 cfs at 00:00 to 4.23 ft / 542 cfs peak at 18:00-18:30 CST (+0.22 ft / +134 cfs). Still rising or at plateau at EOD (4.22 ft / 535 cfs). This is primarily mainstem propagation from St. Joe — the Event 6 pulse arriving downstream.
Signal separation at Harriet: Bear Creek rose only 0.03 ft (2.24→2.27, peaking at 06:00), and CFS moved from 21.6 to 23.5 — trivial. Bear Creek is flat → Harriet's rise is mainstem propagation, not independent Bear Creek contribution. This confirms the signal separation logic.
Richland Creek (07055875): Rose 0.11 ft (1.59→1.70 peak ~10:15 CST) from 0.39" local rain. Modest, consistent with Tier 1 detection.
Bear Creek (07056515): Rose 0.03 ft (2.24→2.27 peak ~06:00 CST). Trivial — 0.42" local rain barely detectable. This is consistent with the dry antecedent pattern at Bear Creek.
Boxley — today's 0.605" rain: - Rain centroid: ~03:00 CST (08:02 UTC peak) - Rise onset: ~04:45 CST - Peak: ~15:15-16:00 CST - Lag to onset: ~1.75 hours - Lag to peak: ~12-13 hours - Rise: +0.21 ft from 0.605" - Transfer ratio: 0.35 ft per inch - Antecedent: Moderate (0.96" 7-day), elevated baseflow at 2.42 ft - Comparison to Event 6 Pulse 1 (Apr 16): 0.38" produced +0.48 ft rise — but that was atop a lower base (2.17 ft) during the initial Event 6 response. Today's smaller rise per inch may reflect that the response is partly masked by ongoing recession from Apr 16's pulse. Alternatively, the Apr 16 rise included pre-wetting effects from trace rainfall during the preceding dry period. Confidence: low — hard to separate superimposed pulses.
St. Joe — Event 6 propagation: - Event 6 Pulse 1 rain: Apr 16, centered ~00:00 CST (05:02 UTC), Richland zone 0.86", St. Joe zone 0.45" - St. Joe rise onset: Apr 17 ~05:00 CST (started rising from ~291 cfs) - St. Joe peak: Apr 18 ~07:15-09:30 CST at 437 cfs - Lag from Event 6 QPE centroid to St. Joe peak: ~31-33 hours - This is consistent with the Event 4 lag of ~33.5 hours (QPE centroid to St. Joe peak).
Harriet — Event 6 propagation: - Harriet rise onset: Apr 17 ~20:00 CST (first sustained uptick above 391 cfs) - Harriet hasn't clearly peaked yet — still at 535 cfs and plateau/slight decline at EOD - Lag from Event 6 QPE centroid to Harriet peak: >40 hours (still ongoing) - Peak-to-peak lag St. Joe → Harriet: St. Joe peaked ~08:00 Apr 18, Harriet peaked ~18:00 Apr 18 = ~10 hours, which is faster than Event 4's 29 hours. However, this may reflect that Harriet hasn't truly peaked yet, or that the Harriet-zone direct rainfall (0.37") is adding to the mainstem propagation, accelerating the apparent rise.
Full Event 6 propagation chain (combining Apr 16-18 data):
The Apr 16 rainfall (~0.3-0.9" across watershed, concentrated in Richland/Cave Creek) produced: - Boxley peak: Apr 16 ~12:45 CST (2.65 ft) — from 0.38" local rain - Ponca peak: Apr 16 ~17:00 CST (167 cfs) — 4.25 hr after Boxley - Pruitt peak: Apr 17 ~07:15 CST (213 cfs) — ~18.5 hr after Boxley - St. Joe peak: Apr 18 ~08:00 CST (437 cfs) — ~43 hr after Boxley - Harriet peak: Apr 18 ~18:00 CST (542 cfs) — ~53 hr after Boxley, still potentially rising
But note: Today's new rainfall (0.6" upper watershed) added a second pulse that complicates attribution. Boxley's second rise today peaks at ~15:15 CST Apr 18, which will propagate downstream and may extend St. Joe and Harriet elevations. I expect St. Joe to show a secondary bump around Apr 19, and Harriet around Apr 19-20.
Event 6 is now a confirmed multi-pulse, multi-day event spanning Apr 15-18+ (and still active).
Two distinct precipitation pulses: - Pulse 1 (Apr 15-16): 0.3-0.9" concentrated in Richland/Cave Creek/upper watershed - Pulse 2 (Apr 18): 0.35-0.72" concentrated in upper/middle watershed (Pruitt/Ponca zones)
Recreational duration tracking: - Ponca: Crossed back above 150 cfs (Low but Floatable) at ~12:45 CST Apr 18, currently 171 cfs. May stay above 150 for another day if Pulse 2 propagation sustains it. - Pruitt: Has been oscillating around 180-200 cfs all day. Briefly touched 200 cfs (Optimal threshold) at 03:30 and 05:15 CST but couldn't sustain it. Remains in Low but Floatable (100-200 cfs). - St. Joe: Has been continuously above 200 cfs (Optimal) since Event 4 began Apr 4. Now at Day 15 of continuous Optimal. Currently 413 cfs. With Pulse 2 propagation arriving, likely to stay in Optimal through at least Apr 25. - Harriet: Continuously above 200 cfs since Event 4. Now at Day 15 of continuous Optimal. Currently 535 cfs and still rising. This is the highest Harriet has been since the Event 4 peak on Apr 5 (2,720 cfs), but well within Optimal range.
St. Joe peak matched prediction almost exactly. My Day 48 forecast was 400-450 cfs; actual peak was 437 cfs. This is encouraging for the developing transfer functions.
Harriet's sustained rise is notable. The rise from 396 cfs (Apr 16 EOD) to 542 cfs (+146 cfs, +37%) over 2 days from what was essentially a moderate, spread-out rain event (~0.4-0.9" over multiple sub-basins) demonstrates the cumulative effect of a large drainage area. Even modest, widespread rainfall across the 2,775 km² above Harriet produces significant flow increases.
Ponca-Pruitt discharge discrepancy remains interesting. Ponca at 171 cfs while Pruitt is at 194 cfs — the downstream gauge showing higher discharge than upstream, despite Pruitt's additional drainage being only 123 km². This suggests that Cove Creek (0.518") and Hoskin Creek (0.689") are contributing meaningfully to Pruitt, or the ongoing Ponca-Pruitt rating curve discrepancy noted in local knowledge continues to affect readings.