Thousands more mountain residents were evacuated from the path of California's biggest wildfire on Friday as worn out firefighters battled gusting winds driving one of the state's worst fire seasons in a decade. Both areas remain under a "red flag warning" due to the dry, hot weather and windy conditions.
National Weather Service meteorologist Duane Dykema said Friday that the blaze still burning near Redding created a fire whirl that uprooted trees and tore roofs from homes. "The sparks that shot out July 23 from that minor incident, California fire officials said, ignited what is now the sixth-most destructive wildfire in state history".
The whirl measured a 3 on the five-level Enhanced Fujita scale, which scientists use to classify the strength of tornados, he said.
"This is a particularly risky situation with extremely low humidity and high winds. New fires will grow rapidly out of control, in some cases people may not be able to evacuate safely in time should a fire approach", the weather service said in its bulletin for the Mendocino area north of San Francisco. The fire has destroyed more than 1,000 structures and damaged almost 200 others.
Firefighting costs have more than tripled from $242 million in the 2013 fiscal year to $773 million in the 2018 fiscal year that ended June 30, according to the California Department of Forestry and Fire Protection, or CalFire.
He says fire whirls are common, but not at the intensity recorded on July 26. "When the winds are strong enough and the fire is hot enough, sometimes, the rising air columns start to rotate".
The fire near Covelo prompted evacuation orders for about 60 homes in the farming and ranching area on the edge of the Mendocino National Forest.
"It's going to be a very dynamic day and the fire has the potential to impact several communities", said Cal Fire Mendocino Complex Fire Operations Section Chief Charlie Blankenheim during his morning briefing August 4, explaining that on Friday afternoon, the Ranch Fire "made a big push to the south and the east, and overnight continued to burn very, very actively and was backing down into the community of Lucerne, and it made a good push across Long Valley Ridge".
Yosemite Valley and other areas of the park have been closed to tourists since July 25 because of heavy smoke from the fire, which has burned almost 100 square miles (259 square kilometers) and is only partially contained.
They included a bulldozer operator whose vehicle almost slipped off a mountain trail three times before it rolled into a ravine and crushed him at the Ferguson Fire near Yosemite National Park, a Cal Fire report said.