SECTION 4: RISK ASSESSMENT
4.5.11 Wildfire
Hazard Background A wildfire is an uncontained fire that spreads through the environment. Wildfires have the ability to consume large areas, including infrastructure, property, and resources. When massive fires, or conflagrations, develop near populated areas, evacuations possibly ensue. Not only do the flames impact the environment, but the massive volumes of smoke spread by certain atmospheric conditions also impact the health of nearby populations. There are three general types of fire spread that are recognized. Ground fires – burn organic matter in the soil beneath surface litter and are sustained by glowing combustion. Surface fires – spread with a flaming front and burn leaf litter, fallen branches and other fuels located at ground level. Crown fires – burn through the top layer of foliage on a tree, known as the canopy or crown fires. Crown fires, the most intense type of fire and often the most difficult to contain, need strong winds, steep slopes and a heavy fuel load to continue burning. Generally, wildfires are started by humans, either through arson or carelessness. Fire intensity is controlled by both short-term weather conditions and longer-term vegetation conditions. During intense fires, understory vegetation, such as leaves, small branches, and other organic materials that accumulate on the ground, can become additional fuel for the fire. The most explosive conditions occur when dry, gusty winds blow across dry vegetation. Weather plays a major role in the birth, growth and death of a wildfire. In support of forecasting for fire weather, the National Weather Service Fire Weather Program emerged in response to a need for weather support to large and dangerous wildfires. This service is provided to federal and state land management agencies for the prevention, suppression, and management of forest and rangeland fires. As shown in Figure 4.21, the National Weather Service Raleigh Forecast Office provides year-round fire weather forecasts for Wake County. Figure 4.21 – Fire Weather Forecast, Wake County
Source: National Weather Service
Wake County Multi-Jurisdictional Hazard Mitigation Plan 2019
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