On 27 September 2009, a large wildfire burned northwest of Yellowstone Lake while smaller fires burned to the south. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASAs Aqua satellite captured this true-color image the same day. Red outlines indicatehotspots associated with wildfires. Thick smoke from the Arnica Fire largely obscures the satellites view of Yellowstone Lake. The smaller fires in the south produce thinner plumes of smoke.
According to a report from the Incident Information System on 29 September 2009, theArnica Fire had burned 9,300 acres (38 square kilometers). Ignited by lightning on 13 September, the fire grew dramatically starting on 24 September, thanks to warm temperatures and high winds. As of 29 September, the fire retained a high growth potential.