California wildfire explodes in size, destroys historic town

• The Plumas County Sheriff's Office said in a Facebook post to residents of the towns of Chester, Lake Almanor Peninsula and Hamilton Branch on Thursday afternoon: "If you are still in the area, you are in danger and you MUST leave now!!
• Evacuation orders were also issued for the Plumas County town of Taylorsville, and also for the towns of Westwood and Susanville in the nearby Lassen County on Thursday night.

The big picture: The fire, the sixth-largest wildfire in state history, razed houses and businesses as it ripped through historic Greenville and surrounding areas.

• Authorities issued mandatory evacuation orders on Wednesday evening for Greenville, about 240 miles northeast of San Francisco, and other communities as the blaze moved in.
• According to AP, the blaze gutted downtown buildings dating back a century or more. "We did everything we could," fire spokesperson Mitch Matlow told the news service. "Sometimes it’s just not enough.”

Threat level: An upper level weather disturbance moving in from the west has made the fire situation even more perilous for firefighters and residents near the blazes, as towering thunderstorms form over and downwind of the fires.

• In addition, wind shifts are suddenly fanning the flames for more than 20 miles in new directions.
• Red Flag fire weather warnings were issued through Thursday evening.
• Such conditions are likely to lead to additional extreme wildfire behavior, including rapid and erratic movement of the blaze and formation of towering pyrocumulus clouds above the fire.

By the numbers: In addition to the Dixie Fire, multiple other wildfires are burning in northern California as well. As of Thursday afternoon eastern time, the River Fire had burned 16,733 acres and was 0% contained.

• The Dixie Fire is now the 6th-largest blaze in California history by acres burned, at more than 320,000 acres so far. That's up at least 24,000 acres in size compared to Wednesday, according to the National Interagency Fire Center.
• Illustrating the dangerous conditions in place, the River Fire exploded from a spark on Wednesday to well over 2,000 acres by dusk and growing quickly, threatening several small towns, and billowing smoke more than 30,000 feet into the sky.

• On Thursday morning it became clear that the River Fire destroyed several homes in the town of Colfax, Calif.

Context: The extremely dry conditions in northern California are the result of a severe drought, which is the worst the West has seen so far this century.

• Northern California as well as the neighboring states of Oregon and Washington have also experienced repetitive heat waves this summer that have dried out the forests even more, and shrunk lakes and reservoirs to record low levels.
• Human-caused climate change is driving an increase in the likelihood and severity of heatwaves and droughts, and is behind a trend toward larger wildfires in much of the West in recent years, studies show.
• Last year was California's worst wildfire season on record. So far, this season is ahead of last year's pace, and the climatological peak of the season doesn't begin for several more weeks.

Rebecca Falconer and Jacob Knutson contributed reporting.