Monsoon rains have created new hazards for areas and communities that were threatened by the Pocket Fire last month.
Scientists say rain can be a surprisingly violent force when it falls on fire scars, each one falling like a little bomb.
The energy of that rain is usually absorbed by grass, shrubs, and pine needles, but that can change after wildfire.
“If that vegetation is not there, then it hits the soil, it hits the ground, hits it with a little bit of an explosive kind of outcome. That explosion of water on the ground can then carry soil, it can carry all kinds of things as it begins to flow,” says Andrew Sanchez Meador, the executive director of Northern Arizona University’s Ecological Restoration Institute.
Adding to the risk: much of the 27,000-acre Pocket Fire burned on the steep slopes of the Mogollon Rim and the West Fork of Oak Creek Canyon.
Scientists don’t yet know how badly it burned those areas, and a U.S. Forest Service Burned Area Emergency Response team is currently evaluating its severity.
Sanchez Meador says the steep slopes burned by the Pocket Fire were largely covered by chaparral and Mogollon shrubland.
Those environments often burn almost completely when a fire moves through them.
“What we also see is those systems respond really fast after fire. There are a lot of sprouting hardwoods in there, and so they'll revegetate pretty quickly. We've been getting some gentle monsoonal rains, and if we have a big enough window, enough vegetation may respond that we could see some interception and not see [much flooding],” Sanchez Meador says.
The National Weather Service warns that flash flooding from the burn scar could impact Oak Creek Canyon, parts of Sedona, and more remote areas like Edge of the World and the Red Rock-Secret Mountain Wilderness.
