After the fire

Fire cycle

Wildfires play an important role in the natural regenerative cycle of many vegetative communities, but the loss of vegetation has lasting effects on the landscape. Communities and sensitive habitats downstream of a fire often face a heightened risk of flooding for years to come.

The physical removal of trees, shrubs, sticks and duff in a burned area increases the speed and volume of runoff, especially on steep slopes. Exposed soil is more vulnerable to erosion, even under moderate precipitation events. Hot fires can actually create a water-repellent layer of topsoil, which further amplifies runoff volume and speed. These changes can significantly increase the risk of dangerous flash floods and debris flows

NWS forecast offices pay special attention to burn scars when storms are imminent. Meteorologists use a variety of short-term forecast models, Doppler radar, and their knowledge of local terrain to determine when the public needs to be alerted to increased flood risk. Hazardous weather outlooks, issued daily, discuss flash flood potential. Flash flood advisories, watches and warnings are issued when conditions are conducive to flooding or are already occurring. While the goal is to provide maximum lead time, when storms develop directly over burn scars, advance warnings may not be possible. 

Burn scar runoff can also deposit increased debris loads into streams and rivers used by sensitive fish species. NOAA Fisheries helps provide local agencies and organizations with best practices for stabilizing burn areas to protect fish habitat. 

Weather station setup at burnscar site
Weather station setup at burnscar site (Mike Seaman)

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Fire cycle