If you looked toward the Cascades last Friday evening, you likely noticed an enormous cauliflower-shaped cloud rising above the skyline. The towering cloud was a pyrocumulus cloud generated by the Little Giant Fire, one of Washington’s largest active wildfires this summer.
The Little Giant Fire, sparked by lightning during the previous week’s thunderstorm, is burning northwest of Leavenworth and has now burned more than 22,000 acres and remains 0% contained. Firefighters continue working under difficult conditions such as low humidity, strong winds and steep terrain that are fueling active fire behavior.
Pyrocumulus clouds, sometimes called “fire clouds” or flammagenitus clouds, form when the intense heat from a wildfire forces hot air, smoke and water vapor high into the atmosphere. As the rising air cools, it condenses into a cloud that resembles a towering cumulus cloud. While they can be impressive to look at, pyrocumulus clouds are often a sign that a wildfire is burning intensely. In some cases, they can even create unpredictable winds or generate dry lightning that has the potential to ignite additional fires.
The cloud from the Little Giant Fire was visible from much of western Washington, including Seattle, Bainbridge Island and Lake Stevens, despite the fire burning dozens of miles away.
Although pyrocumulus clouds aren’t new, scientists and fire managers have observed them becoming more common as larger, hotter wildfires become more frequent across the western United States. Washington’s fire season is also changing. Warmer temperatures, drier vegetation, and longer periods of fire-friendly weather have increased the odds of large, fast-moving fires. As Washington enters the peak of wildfire season, sights like this serve as a reminder that wildfire season is evolving.
