The National Weather Service in Pocatello issued a flash flood warning on July 17 for the Wapiti burn scar region in West Central Custer County, with the alert active from 7:48 p.m. to 9:15 p.m. MDT.
Doppler radar detected thunderstorms dumping heavy rainfall across the burn scar at 7:48 p.m., with precipitation ranging between 0.25 and 0.75 inches. The storm prompted forecasters to warn of flash flooding already underway or expected to develop rapidly in the area.
The Cape Horn Area and Banner Summit were specifically identified as locations experiencing active flooding conditions. Authorities cautioned that the combination of saturated ground and heavy rain would trigger severe debris flows—mixing rock, mud, vegetation, and other loose materials—across the burn scar terrain.
Officials warned that debris flows would likely sweep across roadways, with potential for roads and driveways to be washed away. Creeks, streams, and ditches in the region were expected to experience extensive and severe flooding.
The Wapiti burn scar remains vulnerable to flash flooding and debris flow hazards following wildfire. Burn scars lose vegetation that normally absorbs moisture and stabilizes soil, leaving them prone to rapid runoff and cascading debris during heavy rain events.
Residents and travelers in West Central Custer County were advised to avoid flood-prone areas, particularly near streams and low-lying roads during and immediately following thunderstorms. The National Weather Service recommended staying alert to changing conditions and heeding all warnings issued by local authorities.
What Comes Next
Individuals in affected areas should monitor National Weather Service updates and local emergency alerts. Anyone traveling through Custer County should exercise caution on mountain roads and be prepared to turn back if flooding or debris becomes apparent.