Thousands of people along the southern and western shores of Lake Tahoe were ordered to evacuate on Monday as the Caldor fire intensified amid dry and windy conditions, threatening the popular vacation destination on the California-Nevada border.
The fire had scorched more than 177,000 acres south and west of the lake, and was 14 percent contained as of 11:45 a.m. local time on Monday, according to Cal Fire.
Fire officials estimated that more than 20,000 structures could be threatened by the blaze, the latest to grip California during what has been a particularly unforgiving summer for fire crews in the Western United States.
The National Weather Service issued a red flag warning on Monday for the northern Sierra Nevada and the southern Cascades, meaning that extremely dry conditions and wind gusts of up to 35 miles per hour were likely to cause wildfires to spread in the mountains.
The warning will remain in effect until 11 p.m. on Wednesday for the area, which was cloaked in haze on Monday. Smoke from the fire had deteriorated the air quality to unhealthy levels, the U.S. Forest Service said on Monday on Twitter.
Fire officials warned on Monday that the Caldor fire, which began more than two weeks ago, showed no signs of relenting.
“Fuel conditions remain critical and we still see active crown runs and group torching in the northeastern divisions of the fire,” Cal Fire said on its website on Monday.
Firefighters were battling blazes along a dozen-mile section of an old Pony Express route that connects Gold Rush towns along the thickly forested western slope of the Sierra Nevada. At points, crews drew water from the American River to extinguish spot fires and protect the cabins dotted along Highway 50.
Even at 5,000 feet of elevation, temperatures in the midafternoon were in the 90s, unusually hot for the Sierra. Patches of fire burned on both sides of the road.
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In the heart of the fire, the skies were orange and the valleys a dense slate of impenetrable smoke.
Along the granite cliffs that descend to the Lake Tahoe basin, firefighters chased down a spot fire that had ignited on the slopes in the direction of South Lake Tahoe, the city just a few miles away.
Firefighters and city officials had hoped that the wall of granite would serve as a protective shield for the communities along Lake Tahoe. But winds carried embers that leaped down the cliffs.
Many evacuees grappled with bumper-to-bumper traffic after several major roads in the area were closed. Photographs showed cars at a standstill on Highway 50, the main artery along the southeastern shoreline of the lake.
The mandatory evacuation zone extended from Tahoma, Calif., on the western shore of the lake, to the Nevada border and included the busy resort community of South Lake Tahoe, Calif.
The lake, which is known for its sapphire waters and evergreen-surrounded coves, is particularly popular with vacationers from the Bay Area. It is home to several famous ski resorts and casinos, which are just over the border from South Lake Tahoe in Stateline, Nev. Several concerts that had been scheduled for this week at Harveys Lake Tahoe casino were postponed because of the fire threat, including performances by Phish on Tuesday and Wednesday, and by Miranda Lambert on Thursday.
Although wildfires occur throughout the West every year, scientists see the influence of climate change in the extreme heat waves that have contributed to the intensity of fires this summer. Prolonged periods of abnormally high temperatures are a signal of a shifting climate, they say.
As the Caldor fire threatened Lake Tahoe, the Dixie fire, the largest single-origin wildfire in California history, continued to rage in the northern part of the state.
As of Monday, that fire had burned more than 771,000 acres in five counties and was about 48 percent contained, according to Cal Fire.
In a Facebook post on Friday, Cal Fire said that more than 15,200 firefighters were on the front lines of 14 active large wildfires that had burned over 1.68 million acres.