FLAGSTAFF, Ariz. — Coconino County officials say the Schultz and Pipeline Fire burn scars experienced what is believed to be the largest, most widespread, and continuous rainfall event since rain gauges were installed following the 2010 Schultz Fire.
The intense monsoon storm moved across the burn scar Saturday night, triggering more than 150 rain gauge threshold alerts between 8:48 p.m. and 11:00 p.m. across the 13 monitoring stations located throughout the Schultz and Pipeline Fire flood areas.
Every rain gauge recorded significant rainfall during the event. The three northernmost gauges measured 3.89 inches, 2.48 inches, and 2.32 inches of rain, while seven additional gauges recorded more than one inch of rainfall.
County officials said the previous largest rainfall event occurred in 2018, when roughly six inches of rain fell in about an hour. However, that storm was largely confined to a single watershed, while Saturday night’s rainfall covered a much broader area.
Minimal Flooding Despite Historic Rainfall
Despite the unprecedented rainfall, officials say the exceptionally dry conditions across the burn scars helped limit flooding.
Field cameras operated by the Coconino County Flood Control District and observations from County Public Works crews recorded only about six inches of water entering the flood channel along Brandis Way. Storm drain inlets in the other seven flood corridors serving the Timberline and Wupatki Trails neighborhoods showed little to no runoff from the burn scars.
During the storm, Coconino County issued two Shelter-in-Place Emergency Notifications, while the National Weather Service issued a Flash Flood Warning after rainfall thresholds and radar estimates indicated the potential for dangerous flooding.
Future Storms Could Produce Greater Flooding
While Saturday’s storm produced relatively minor runoff, officials caution that conditions have now changed significantly.
The heavy rainfall has saturated much of the burn scar, meaning future monsoon storms are expected to generate much larger and faster-moving flood flows.
“After three years of very limited monsoon rainfall events, it appears that this summer may set rainfall records, so please stay alert and keep your children inside when rainfall is expected,” said Lucinda Andreani, Administrator for the Coconino County Flood Control District.
Since the 2022 Pipeline Fire, the Flood Control District has invested more than $120 million in watershed restoration projects and flood mitigation infrastructure across the nine affected watersheds.
Officials say the system is designed to manage approximately two inches of rainfall in 45 minutes, but warn that as soils become increasingly saturated, floodwaters will rise more quickly and may eventually exceed the system’s capacity.
Residents living within the Schultz/Pipeline Flood Area are urged to remain vigilant throughout the remainder of the monsoon season and pay close attention to emergency notifications whenever heavy rain is forecast.
Residents can monitor real-time rainfall totals from the area’s rain gauge network by visiting the City of Flagstaff’s online rainfall map.
