A powerful Pacific storm system looks to bring heavy rain to parts of Northern California over the next few days. As California transitions into it’s “wet” season, burn scars left from California’s devastating fires this year are at a higher risk of flooding.
California’s wet season runs from October through March producing a majority of California’s annual rainfall. Scorched earth that are burn scars are prone to flooding, erosion and rock and mudslides. Without the plants, trees and vegetation to hold the soil in place and absorb rainfall, mud and rock slides can occur especially on hillsides when rain moves in.
Locations downhill and downstream from burned areas are very susceptible to flash flooding and debris flows, especially near steep terrain. Rainfall that would normally be absorbed will run off extremely quickly after a wildfire, as burned soil can be as water repellant as pavement. As a result much less rainfall is required to produce a flash flood or mudslide within a burn scar.
It can take years for burn scars to heal as vegetation re-establishes, so this year’s scars are certainly susceptible to flash flooding in this year’s wet season, if not longer.
Locations within and below the elevation of burn scars across California are in danger of inundation from flash flooding and/or debris flows with this week’s expected rain.
Meteorologist Mike Morrison