File:Ferguson Fire in Sierra National Forest, California (MODIS 2018-07-21).jpg

English: A little more than a year after the residents of the mountain town of Mariposa, California were evacuated due to the encroachment of the devastating Detwiler Fire, residents are again on alert as an expanding fire near Yosemite National Park spreads towards the town. The Detwiler Fire ignited on July 16, 2017 and burned more than 81,000 acres, destroyed 63 residences, 67 minor structures, 1 commercial structure, and damaged over a dozen additional structures before being contained.

The Ferguson Fire was first reported on July 13, 2018, in the Sierra Nevada National Forest northeast of the site of the 2017 Detwiler Fire. According to Inciweb, as of July 20, much of the Ferguson Fire is burning in steep, rugged terrain with little to no access roads. Mandatory and advisory evacuations are in place in several areas but no homes have been damaged or destroyed. The fire has consumed 22,892 acres and is only 7% contained.

The Ferguson Fire killed has killed one firefighter to date. The firefighter exposure risk is considered high due to very hot conditions and limited access requiring heavy rotor wing support. The Ferguson Fire is managed under unified command between the US Forest Service, California Interagency Incident Management Team 4, CALFIRE, and the Mariposa County Sheriff’s Office. There are 2,711 personnel are currently engaged on the fire which includes 203 engines, 39 water tenders, 16 helicopters, 58 handcrews, and 41 dozers.

Other fires have burned in the Sierra Nevada Mountains in recent days, all south or south-east of the Ferguson Fire. The Lion’s Fire began from a lightning strike on July 11, 7 miles southwest of Mammoth Lake and consumed 4,064 acres before being 100% contained on July 16. George’s Fire started from a lightning strike on July 8 north of Lone Pine. As of July 14, the fire was at just over 2,800 acres and was 42% contained. The fireline was moving towards steep, inaccessible terrain and the plan was to allow burnout against steep granite walls in an inaccessible location. Finally, the Horse Creek Fire was spotted on July 19 near Mineral King and was only 2 acres in size as of that date. It is burning near the Fowler Fire, which has little potential for expansion.

On July 18, the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite acquired a true-color image of fire and smoke over the Sierra Nevada Mountains. Low cloud (fog) swathes the west coast of California while a bank of high cloud drapes across the southern section of the image. Gray streaks and clouds of smoke hang over most of the visible landscape of California. Red hot spots mark areas where the thermal bands on the instrument detected high temperatures – in this case actively burning fire. The hot spots appear to be in a ring shape, but they are not separate fires. The shape is caused due to the consumption of all fuel in the center of the fire as the active fire spreads outward, consuming fresh fuel on the edges of the fire.