Burning for weeks, the Wapiti and Middle Fork Complex fires have charred tens of thousands of acres.
In late July 2024, a lightning strike started the Wapiti fire in Idaho, which expanded to over 100,000 acres by early September due to worsening conditions. A temperature inversion initially helped suppress the fire, but once lifted, the fire intensified, leading to the closure of national forests and highways, and evacuation orders around Stanley. By September, red flag warnings predicted further escalation due to adverse weather conditions.
Wapiti Fire Ignition and Spread
On July 24, 2024, lightning ignited what became known as the Wapiti fire in central Idaho. Fire activity ramped up in late August, expanding its footprint to over 100,000 acres (400 square kilometers) by early September. The Wapiti fire, as well as the Middle Fork Complex fires burning nearby, have spurred evacuation orders and highway and public lands closures.
Satellite Observation of the Growing Blaze
The OLI (Operational Land Imager) on Landsat 8 acquired these images of fire activity on August 31, 2024, at about 12:30 p.m. local time (18:30 Universal Time). Thick smoke fills the valleys, while plumes from active blazes drift to the north. At this point, the Wapiti fire, on the right side of the image, had reached about 95,000 acres, and its perimeter was uncontained. Fires in the Middle Fork Complex, which spanned about 55,000 acres on this date, burn on the left side of the image.
Impact of Temperature Inversion on Fire Suppression
On the morning of August 31, a temperature inversion—a warm layer of air capping a cooler one—trapped smoke in low-lying areas. Inversions can suppress fire activity by preventing sunlight and heat from reaching the ground. According to InciWeb, forecasters expected the inversion to lift around noon, with the potential for fire behavior to increase after that.
Rapid Expansion and Response Measures
The Wapiti fire, shown in this detailed image, had burned about 9,000 acres (36 square kilometers) in its first month. After August 20, it expanded much more rapidly. By September 3, it had grown twelve times larger to approximately 108,000 acres. As fire activity increased, officials ordered the closure of portions of the Boise, Sawtooth, and Salmon-Challis national forests and nearly 50 miles of State Highway 21 heading west out of Stanley. Residents in and around Stanley were issued evacuation orders or preparation notices. Ground-based photographers captured images of dense smoke plumes and red skies.
Forecasting Severe Fire Weather
On September 3, more fire weather was in store for the area. A red flag warning was in effect through the evening, with scattered thunderstorms and wind gusts up to 50 miles (80 kilometers) per hour in the forecast.
NASA Earth Observatory images by Michala Garrison, using Landsat data from the U.S. Geological Survey.
Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.