Wildfires Generate Thunderstorms, Pose Increased Risks

Why it matters locally: Oregon, a state frequently impacted by large wildfires, faces increased risks from pyrocumulonimbus events that can create erratic winds, spread embers, and generate lightning, complicating suppression efforts for agencies like Clackamas Fire District #1 and Portland Fire & Rescue.

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Certain wildfires generate intense heat and smoke plumes that rise into the atmosphere, forming a type of cloud system known as pyrocumulonimbus. NASA describes these formations as the "fire-breathing dragon of clouds" due to their visual characteristics and the phenomena they produce. These fire-generated thunderstorms differ from typical thunderstorms. Instead of forming from atmospheric instability alone, the extreme heat from a large wildfire drives the updraft that creates the cloud. As the smoke and gases cool at higher altitudes, water vapor condenses, forming a towering cloud structure. Pyrocumulonimbus clouds can significantly influence wildfire behavior. They often create strong, erratic winds that spread embers and accelerate the fire's advance. Additionally, these clouds can produce lightning, which can ignite new fires far from the original blaze, complicating suppression efforts and increasing the total area affected. The formation of these clouds indicates a particularly energetic and dangerous wildfire. Firefighters and meteorologists monitor these events to anticipate sudden changes in fire direction, intensity, and the potential for new ignitions.