Thunderstorms producing heavy rain over the burn scar will cause a debris flow through the Strawberry River. It is expected to impact the river from Strawberry Reservoir to Starvation Reservoir.
Glen Merrill, a hydrologist with the NWS, said a small portion of the burn scar above the Pinnacles area received about 0.8 of an inch of rain within half an hour.
“With already high river levels now, you put almost an inch of rain down and it just runs off the landscape very quickly," he said. "So we're expecting those flows to rapidly increase in downstream areas, especially in the Pinnacles.”
Merrill said that can create extremely hazardous conditions.
“It comes on very quickly and then subsides relatively quickly thereafter,” he said.
The NWS urged drivers to avoid flooded roads, saying most flood deaths happen in cars.
The flash flood warning is set to expire at 5:15 p.m. Monday.
Flash Flood Warning including Duchesne County, UT, Wasatch County, UT until 5:15 PM MDT pic.twitter.com/XgNvTMnb2I
— NWS Salt Lake City (@NWSSaltLakeCity) May 22, 2023