Light to moderate rainfall returned to the watershed today after four consecutive dry days (3/11-3/14). The rain was concentrated in a brief pulse, with almost all precipitation falling in a single 1-hour window around 15:06-16:06 UTC (10:06-11:06 CST / approximately 2-4 PM CST based on gauge responses).
Zone averages (24hr totals): | Zone | Total (in) | Peak 1hr (in) | Notes | |------|-----------|---------------|-------| | Pruitt | 0.482 | 0.443 | Highest zone average; Cove Creek 0.524", Hoskin Creek 0.440" | | Ponca | 0.413 | 0.520 | Whiteley Creek 0.556" (highest single HUC12), Beech Creek 0.458" | | Bear Creek | 0.309 | 0.217 | Moderate, distributed | | Richland | 0.296 | 0.311 | Light | | St. Joe | 0.236 | 0.346 | Light average across 14 HUC12s; Flatrock Creek 0.523" was a hotspot | | Harriet | 0.172 | 0.163 | Minimal | | Boxley | 0.161 | 0.098 | Minimal |
Spatial pattern: This was primarily a Ponca-Pruitt zone event. The heaviest rain fell in the Whiteley Creek (0.556"), Cove Creek (0.524"), Flatrock Creek (0.523"), Beech Creek (0.458"), and Hoskin Creek (0.440") HUC12s — a concentrated band across the upper-middle watershed. The headwaters (Boxley) and lower watershed (Harriet) received minimal rain.
Temporal character: Nearly all rain fell in a single burst. Max 3hr ≈ max 6hr ≈ max 12hr ≈ total 24hr for every HUC12, confirming a brief convective pulse rather than prolonged stratiform rain.
Ponca (07055660): Declined from 197 cfs at midnight to a minimum of 182 cfs at 14:45 CST, then reversed and rose to 207 cfs by 21:45 CST. The rise of ~25 cfs (+14%) from the 182 cfs low represents a small but measurable response. Ponca crossed back above 200 cfs by ~20:00 CST and ended the day at 207 cfs. This is a recession arrest and modest rebound, not a significant event rise.
Pruitt (07055680): Continued declining from 308 cfs at midnight to ~281 cfs by 14:00 CST, then showed a small uptick to ~302 cfs around 17:45 CST before resuming decline to 278 cfs at EOD. Height similarly showed a brief bump from 4.42 ft to 4.49 ft around 17:30-17:45. The Pruitt gauge precip total of 0.27" (gauge tipping bucket) is consistent with the MRMS zone average of 0.482". Response: marginal — approximately +20 cfs / +0.07 ft bump above the recession trend, lasting ~3 hours.
St. Joe (07056000): Continued declining from 722 cfs to ~598 cfs at EOD. However, the St. Joe height data shows increased noise/oscillation starting around 15:45 CST (height jumping between 4.64-4.76 ft in short intervals). The CFS data similarly oscillates (598-656 range in the last 8 hours). This is likely instrument noise from turbulence rather than a real signal — the overall trend remains downward. The gauge precip was only 0.07". No significant response to today's rain.
Harriet (07056700): Steady decline from 878 cfs to 763 cfs. No deviation from recession. No response.
Boxley (07055646): Brief uptick from 2.55 to 2.59 ft around 15:00-16:00 CST (+0.04 ft), then returned to 2.55 ft. Consistent with the very light 0.161" of rain — barely detectable.
Richland Creek (07055875): Small bump from 1.42 to 1.47-1.48 ft around 20:00-22:15 CST (+0.05 ft). With only 0.30" of rain, this is at the noise floor. Consistent with the detection threshold of >0.6" for a real response.
Bear Creek (07056515): No response. Height dropped from 2.48 to 2.46 ft. Discharge declined from 15.0 to 14.1 cfs. The 0.31" of rain produced zero detectable rise. Consistent with the >0.6" (likely >0.8") detection threshold hypothesis.
Ponca — marginal event (near detection threshold): - Rain: 0.413" zone average (peak Whiteley 0.556"), delivered ~14:00-15:00 CST - Response: +25 cfs from recession trough (182→207 cfs), beginning ~15:30-15:45 CST - Lag: ~1-2 hours from peak rainfall to initial rise - Antecedent: Dry — only 0.67-1.01" 7-day precip across Ponca zone HUC12s. This is the driest antecedent condition observed in the study. - Assessment: 0.4" on dry antecedent produced barely detectable response (~14% rise). This is at the boundary of detection threshold for Ponca. Compare with Event 1 (1.0" on dry antecedent → +95 cfs/+113%) and Event 3 (0.83" on wet antecedent → +350 cfs/+178%). The response scales roughly with rainfall amount but the dry antecedent condition also suppresses it. Supports the ~0.3" detection threshold estimate but demonstrates that near-threshold rainfall on dry soils produces only marginal signal.
Pruitt — marginal event: - Rain: 0.482" zone average (Cove Creek 0.524"), delivered ~14:00-15:00 CST - Response: +20 cfs bump above recession trend (~281→302 cfs), beginning ~15:30 CST - Lag: ~1.5 hours from peak rainfall - Antecedent: Dry — 0.51-0.55" 7-day precip in Pruitt zone - Assessment: 0.48" on dry antecedent produced marginal bump. Pruitt also received upstream wave from Ponca's small response, so the local vs propagated signal is ambiguous. Near detection threshold on dry antecedent.
Bear Creek — non-detection: - Rain: 0.31" zone average - Response: None - Antecedent: Dry (0.55-0.72" 7-day) - Assessment: 0.31" on dry antecedent → zero response. Further supports the >0.6" (likely >0.8") threshold. This is now the fourth non-detection at Bear Creek (0.0", 0.52", 0.31" all produced nothing; only 1.2" produced a response).
No significant propagation event to track. The small bumps at Ponca and Pruitt were local responses to local rain, not propagated waves.
Not applicable — this was a single brief pulse after four dry days.
7-day antecedent precipitation dropped dramatically. As predicted on Day 14, Event 2's rainfall (3/07) rolled out of the 7-day window. Antecedent values dropped from 1.3-3.2" range (Day 14) to 0.24-1.01" range (Day 15) — a 50-75% reduction. The watershed is now in its driest state of the study. This is a valuable data point: today's marginal responses to 0.4-0.5" rain on dry soil contrast sharply with the strong responses to similar rainfall amounts on wet soil (Events 2-3). This directly validates the antecedent moisture amplification hypothesis.
St. Joe height oscillation. The St. Joe height data shows unusual oscillation (0.06-0.08 ft swings between consecutive 15-min readings) starting around 15:45 CST. This doesn't correspond to any significant rainfall in the St. Joe zone (only 0.07" at the gauge). It may be instrument noise, wind effects, or possibly a localized convective cell producing brief turbulence near the gauge. The CFS data shows corresponding oscillation. This is the first time such oscillation has been observed at St. Joe during recession, and it complicates the recession rate calculation for this segment of the day. Treating this as noise, not signal.
Recession continues (Day 5 of dry recession): This is the longest clean recession period in the study (3/12 through 3/15, with today's rainfall being too small to significantly interrupt). Updated recession observations:
| Gauge | 3/14 EOD | 3/15 EOD | 24hr Change | Rate (%/hr) |
|---|---|---|---|---|
| Ponca | 195 cfs | 207 cfs* | +6% (rain bump) | N/A (interrupted) |
| Pruitt | 308 cfs | 278 cfs | -9.7% / 24hr | ~0.42%/hr |
| St. Joe | 732 cfs | 613 cfs | -16.3% / 24hr | ~0.74%/hr |
| Harriet | 878 cfs | 763 cfs | -13.1% / 24hr | ~0.58%/hr |
Pruitt's recession rate has slowed further from ~0.81%/hr (Day 14) to ~0.42%/hr (Day 15), indicating it's approaching baseflow. At 278 cfs, Pruitt is still in Optimal (>200 cfs) but declining. At current rate, Pruitt will cross below 200 cfs around 3/18-19 (~3-4 more days).
Ponca re-entered Optimal briefly. Ponca crossed above 200 cfs at ~20:00 CST due to the rain bump. However, this is marginal and the pre-rain trajectory was 182 cfs and declining. Without follow-up rain, Ponca will likely drop back below 200 cfs within 24 hours. The Event 2+3 Optimal window at Ponca is now definitively over — the 3/14 crossing was the end of the sustained window. Today's brief exceedance is a separate, marginal event.
Recreational status update: - Ponca: Marginal — oscillating around 200 cfs boundary. "Low but Floatable" to borderline "Optimal." - Pruitt: Still Optimal at 278 cfs, declining. Projected to remain Optimal ~3-4 more days. - St. Joe: Optimal at 613 cfs. At 0.74%/hr decline, will cross 200 cfs in ~160 hours ≈ ~6.5 more days ≈ ~3/22. - Harriet: Optimal at 763 cfs. Will remain Optimal into late March.