The National Weather Service office in Great Falls issued a Flash Flood Watch early Wednesday morning for the Horse Gulch burn scar, including Riverside Campground, with the watch running through midnight Wednesday night. The concern is heavy rainfall falling on ground that has already been stripped of vegetation by fire — a combination that can produce fast-moving floods and debris flows with little warning.
Burn scars dramatically increase runoff because the soil loses its ability to absorb water after intense heat. On steep terrain, that runoff can pick up rocks, logs, and other debris, sending it downslope at dangerous speeds. The Horse Gulch burn scar poses that risk to Riverside Campground and any low-lying areas downstream.
The NWS watch was issued at 3:42 a.m. MDT on August 13. Residents and recreationists with any plans in or near the Horse Gulch area are being advised to monitor conditions closely and be prepared to move to higher ground quickly if rainfall begins. Campers at Riverside Campground should be aware that the typical warning time for debris flows on burn scars can be measured in minutes, not hours.
The watch is part of a broader pattern this week of weather and fire intersecting across central Montana. Burn scars from the current fire season are scattered across the region, and any substantial rainfall event carries elevated flood risk wherever those scars are located.