Zero precipitation across the entire watershed today. All 37 HUC12s report 0.0" for the 24-hour period. No rain fell anywhere in the Buffalo River watershed on April 19.
7-day antecedent precipitation has increased relative to yesterday due to the Apr 18 Pulse 2 rain now being fully captured in the rolling window. Current 7-day values range from 0.77" (Bratton Creek, ungauged) to 1.50" (Boxley), with most HUC12s in the 0.9-1.4" range — moderate antecedent moisture.
Despite zero new rainfall, several gauges showed notable movement today as Event 6 Pulse 2 (Apr 18, 0.3-0.7" widespread) propagated through the system:
Upper watershed — recession: - Boxley: 2.57 ft → 2.45 ft, steady decline of -0.12 ft through the day. The Pulse 2 rise that peaked at 2.63 ft on Apr 18 ~15:00-16:00 CST is now receding cleanly. Boxley has dropped back to pre-Pulse 2 levels. - Ponca: 169 cfs → 147 cfs, declining all day from 169 at midnight to 147 at EOD. Ponca is approaching the 150 cfs "Low but Floatable" lower boundary. The Pulse 2 bump that peaked at 173 cfs on Apr 18 ~20:00 CST has already receded. Ponca dropped below 150 cfs at ~21:00 CST today — this marks the end of the extended floatable period that began during Event 4. - Richland Creek: 1.65 ft → 1.56 ft, steady decline. Now at the lowest level since before Event 6. - Bear Creek: 2.25 ft → 2.23 ft, minimal change, essentially at baseflow.
Middle watershed — Pruitt shows a clear propagation bump: - Pruitt: Started at 4.06 ft / 194 cfs, rose through the early morning to peak at 4.20 ft / 232 cfs around 07:45-10:15 CST, then declined through the afternoon to end at 4.09 ft / 203 cfs. This +0.14 ft / +38 cfs rise with no new local rain is Event 6 Pulse 2 propagation arriving from the upper watershed. Pruitt returned to Optimal (>200 cfs) and stayed there all day — currently right at the boundary at 203 cfs.
Lower watershed — St. Joe shows late-day secondary rise: - St. Joe: Held relatively flat at ~4.19-4.22 ft / 417-429 cfs through most of the day, then began a clear rise starting ~14:30 CST, accelerating through the evening to reach 4.33 ft / 474 cfs by 21:00 CST and holding through EOD. This is a +0.13 ft / +53 cfs rise from the afternoon low. This is the Event 6 Pulse 2 propagation wave arriving at St. Joe, as predicted yesterday. The rise began ~14:30 CST, which is ~30 hours after the Apr 18 rain centroid (~08:00 UTC = ~03:00 CST Apr 18). St. Joe appears to still be rising or plateauing at EOD.
Event 6 Pulse 2 propagation — timing analysis:
The Apr 18 Pulse 2 rain fell primarily between ~03:00-06:00 UTC (roughly 09:00 PM Apr 17 - midnight CST), concentrated in the upper/middle watershed (Boxley 0.605", Ponca zone 0.614", Pruitt zone 0.603", St. Joe zone 0.464").
Propagation velocity (peak-to-peak estimates for Pulse 2): - Boxley → Ponca: ~4-5 hours (consistent with prior events) - Ponca → Pruitt: ~12-14 hours (slower than Event 4's 10 hr, consistent with lower flow) - Pruitt → St. Joe: St. Joe still rising, so full lag TBD. Rise began ~7 hours after Pruitt peak — consistent.
Classic downstream propagation pattern observed today with zero new precipitation — a textbook case:
The Pulse 2 wave is moving downstream through the system. Upper gauges (Boxley, Ponca) are receding while middle gauges (Pruitt) peaked this morning and lower gauges (St. Joe) are still rising. Harriet hasn't seen the wave yet.
Propagation sequence timeline (Pulse 2): - Boxley peak: Apr 18 ~15:30 CST (2.63 ft) - Ponca peak: Apr 18 ~20:00 CST (173 cfs) — +4.5 hr - Pruitt peak: Apr 19 ~08:00 CST (232 cfs) — +16.5 hr from Boxley - St. Joe peak: Not yet reached — still rising at 474 cfs at EOD Apr 19 - Harriet peak: Expected Apr 20
This is occurring at moderate baseflow (Pruitt ~190 cfs, St. Joe ~420 cfs), providing a mid-range data point for propagation velocities. The propagation is notably slower than Event 4 (which had higher flows and thus faster wave speeds).
Event 6 status update: Event 6 Pulse 2 propagation is now clearly tracked through the system. Key observations:
Recreational duration tracking: - Ponca: Dropped below 150 cfs ("Low but Floatable" lower boundary) at ~21:00 CST today. The continuous floatable period (>150 cfs) that began during Event 4 on ~Apr 4 has ended — total duration: ~16.5 days. This is a remarkable sustained period driven by Events 4, 5, and 6 stacking. - Pruitt: Returned to Optimal (>200 cfs) today due to Pulse 2 propagation. Was in Optimal from Event 4 start (~Apr 4) through ~Apr 12, dropped to Low-but-Floatable, then had brief Optimal touches on Apr 17 and is now back in Optimal. Currently at 203 cfs, right on the boundary — will likely drop back to Low-but-Floatable tomorrow. - St. Joe: 474 cfs at EOD, still rising. Has been continuously in Optimal (>200 cfs) since Event 4 began Apr 4. Now at Day 16 of continuous Optimal. - Harriet: 529 cfs at EOD. Has been continuously in Optimal since Event 4. Day 16 of continuous Optimal. The Pulse 2 propagation wave should arrive tomorrow and may push Harriet slightly higher before beginning final recession.
Surprising St. Joe late-day rise magnitude: The St. Joe rise from ~420 to 474 cfs (+54 cfs, +13%) is larger than expected from only the mainstem propagation of 0.4-0.7" of rain. Given that Richland Creek is declining (1.65→1.56 ft) and Bear Creek is flat, the source must be either: (a) mainstem propagation from Pruitt carrying more volume than apparent from CFS alone, (b) delayed subsurface contributions from the large St. Joe zone sub-watersheds (Little Buffalo, Big Creek, Cave Creek) responding slowly to yesterday's 0.37-0.43" rain in those areas, or (c) combined effect of both. The rise pattern — flat through midday, then accelerating — is more consistent with mainstem propagation arrival. I'll update the St. Joe response model: even 0.4" widespread rain produces a detectable 50+ cfs bump at St. Joe when antecedent conditions are moderate.
No contradiction with existing hypotheses. The propagation timing at lower flows (slower than Event 4) is consistent with the expectation that wave speed correlates with flow magnitude.