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The Mosquito Fire burns in the Tahoe National Forest on the evening of Sept. 8, 2022.
—Updates: Get info on the Mosquito Fire from Cal Fire. —Information line: Call 211 for information from Cal Fire. —Evacuation maps: Find from Placer County and El Dorado County. A list of evacuation shelters can be found here. —Live cameras: Wildfire cameras tracking the fire are available from AlertWildfire.
One more day of "excessive heat" is in the forecast for the area around the Mosquito Fire. The National Weather Service's Sacramento office is forecasting high temperatures between 100 and 114 degrees in the valleys and foothills and up to 105 degrees in the mountains. The excessive heat advisory is set to expire at 8 p.m. Friday.
"The weather in the fire area will continue to be extremely hot and dry overnight and into tomorrow," Cal Fire said in a statement Thursday evening. "Combined with very low fuel moistures fire conditions are likely to replicate today’s behavior during the overnight period and into tomorrow’s operational period."
Remarkable timelapse footage captured by AlertWildfire cameras shows the Mosquito Fire raging and swirling as the sun set on the Tahoe National Forest on Thursday. Cameras set up on Little Bald Mountain show the blaze emitting a massive pyrocumulus cloud so powerful it churned like a vortex.
15 minute timelapse to 7:55pm with column rotation on #MosquitoFire 9/8/2022 #CAwx @FireWeatherLab @nplareau #firewx https://t.co/L2KVDmTJqv pic.twitter.com/CGrqikn1AJ
#MosquitoFire pyroCb has been exhibiting broad rotation all afternoon, with some apparent brief spin-ups, but this one looks like the most significant one so far. #CAwx #CAfire #PyroVortex https://t.co/IOpHuWMVLk
Wildfires are capable of creating their own weather, sometimes referred to as a firestorm. As the fire burns hot and intense on the ground, heat rises rapidly, creating a vacuum. Air rushes in to fill that vacuum, and the resulting updraft is powerful enough to carry debris, form a firenado and make its own lightning.
At a town hall Thursday night, officials said the Mosquito Fire that started in Placer County ballooned to 13,705 acres and made a 5,000-acre run into El Dorado County. Matthew Radtke, superintendent with the American River Hotshots, said mitigation measures were made to protect the town of Foresthill.
"It is getting close to some structures," Radtke said. "I want you to know that we do have resources in there to protect all the structures." He later added, "We feel proud of the progress we have made in Foresthill."
Georgetown Fire Dept. 63 and Otter Creek school still stand tall after #mosquitofire made run through Volcanoville destroying other structures early this afternoon. @abc10 pic.twitter.com/yQlHnwgxpo
Radtke said the fire crossed the American River near Volcanoville about noon Thursday.
"Volcanoville has definitely been impacted," a Cal Fire division chief said. "We did have some structures destroyed there for sure. I can't say exactly how many, but it's definitely not the whole community by any stretch."
Watch the full town hall on Facebook.
Cal Fire held a town hall in Auburn for residents evacuated by the Mosquito Fire at 7 p.m. You can watch the live stream on Facebook.
California's Mosquito Fire pumped out a towering 35,000 foot tall pyrocumulus cloud on Sept. 8, 2022.
Infrared video, taken by aircraft flying over the Mosquito Fire about 5 p.m. Thursday by the state Office of Emergency Services for its Fire Integrated Real-time Intelligence System, was posted on Twitter and showed the fire had grown to 13,705 acres.
OES Intel 12, Sept 8th on the #MosquitoFire, TNF. Fire is mapped at 13,705 acres at 17:02 hours. Video 2 of 2 pic.twitter.com/Ug6hcGz2xw
California Gov. Gavin Newsom declared a state of emergency due to the Mosquito Fire burning in Placer and El Dorado counties, and the Fairview Fire in Riverside County, his office announced Thursday.
The Mosquito Fire has consumed 6,807 acres with zero containment as of Thursday afternoon, while the Fairview Fire has blackened 23,919 acres and is 5% contained.
PG& said that "out of an abundance of caution," it filed a report Thursday regarding an electrical fault that occurred close to the time the Mosquito Fire ignited on Tuesday and near the location where the fire started at Oxbow Reservoir in Placer County, a statement from the utility said. The incident report indicated that the US Forest Service placed caution tape around the base of the transmission pole (60Kv).
"Thus far, PG& has observed no damage or abnormal conditions to the pole or its facilities near the reservoir and has not observed any downed conductor in the area or any vegetation or tree on the line," the utility said in its statement to SFGATE. "The 60-kilovolt transmission pole was replaced with a steel pole approximately 10 years ago. An enhanced inspection of the pole and equipment was performed within the last five months, and no adverse conditions were identified."
PG& filed for bankruptcy in 2019 in the face of billions of dollars in claims for wildfires started by equipment owned by the utility.
The cause of the Mosquito Fire is under investigation.
Burning in tinder-dry vegetation amid scorching weather, the Mosquito Fire exploded Thursday, pumping out massive amounts of smoke. The sooty air flooded communities in the surrounding Sierra foothills, and pushed into the Sacramento Valley and Lake Tahoe basin. The Sacramento Metro Air District issued a smoke advisory for Thursday, warning of unhealthy air quality levels.
Read more about the smoke forecast on SFGATE.
Smoke from #MosquitoFire getting pushed southwards from North Lake Tahoe as evening winds pick up… @spann pic.twitter.com/icxas5ELdd
The Mosquito Fire has jumped the American River into El Dorado County, prompting more evacuation orders. The communities of Volcanoville, Bottle Hill and Georgetown must evacuate immediately. Officers from local sheriff's offices, police departments and CHP are going door-to-door contacting residents who must leave.
"Due to rapidly changing fire conditions and the spread of the Mosquito Fire across the American River into El Dorado County, the El Dorado County Sheriff's Office has ordered an immediate evacuation," Cal Fire said in a statement. A live updating evacuation map of El Dorado County can be found here.
Firefighters battle the Mosquito Fire burning on Michigan Bluff Road in unincorporated Placer County, Calif., on Wednesday.
Evacuation orders are spreading in Placer County as the Mosquito Fire makes a run toward populated areas Thursday afternoon.
The Placer County Sheriff's Office is ordering everyone to leave Todd Valley immediately. A map of evacuation zones can be found via the Placer County Sheriff's Office; red areas are under orders to leave now, while yellow areas are under an evacuation warning. Locations under a warning should be ready to leave at a moment's notice.
"Anyone coming into Foresthill will be turned around at Foresthill Road and Old Forresthill Road," the sheriff's office tweeted.
People watch from a distance as the Mosquito Fire burns near Michigan Bluff in unincorporated Placer County, Calif., on Wednesday.
The Mosquito Fire is pumping out a massive pyrocumulus cloud Thursday afternoon, signaling that the wildfire in the Tahoe National Forest is growing at a rapid rate. Cal Fire reported that the fire had jumped the American River and spread from Placer County into El Dorado County and was pushing toward the town of Volcanoville.
UCLA climate scientist Daniel Swain shared a webcam image of the cloud on Twitter. Swain estimated it was 35,000 feet tall. "These webcam snapshots are pretty amazing/alarming, especially as #MosquitoFire is actively impacting populated areas near Volcanoville," Swain wrote. Volcanoville is about an hour's drive northeast of Auburn.
Now officially another pyrocumulonimbus, with plume heights to ~35,000 feet and increasing. These webcam snapshots are pretty amazing/alarming, especially as #MosquitoFire is actively impacting populated areas near Volcanoville. #CAwx #CAfire https://t.co/zaY067QpHV pic.twitter.com/Z2WahPM6oF
A similar cloud formed over the fire on Wednesday afternoon. National Weather Service forecaster Emily Heller told SFGATE that pyrocumulus clouds form when "you have an unstable atmosphere and there's a lot of heat from the fire."
Heller continued, "It lifts air and creates these bigger looking clouds above it. Technically, it's the same cloud that develops over volcanoes."
Placer County is posting its evacuation map here, and El Dorado County is posting evacuations here.
The Fire Integrated Real-time Intelligence System mapped the fire's burn area at 8,265 acres as of 1:33 p.m.
OES Intel 12, Sept 8th on the #MosquitoFire, TNF. Fire is mapped at 8,265 acres at 13:33 hours. pic.twitter.com/RuCTjfVLY1
A fast-growing wildfire tearing through tinder-dry vegetation in the Sierra Nevada Range near the town of Foresthill grew another 1,100 acres overnight and continues to threaten multiple communities, important infrastructure and hundreds of homes, Cal Fire said Thursday morning.
The Mosquito Fire shows no signs of slowing down and by sunrise had already pumped out a massive smoke cloud that towered above Placer County, signaling extreme fire activity on the ground.
Cal Fire said “critical infrastructure” is threatened, including the Placer County Water Agency pump station and dam, Placer County Fire Repeater Site, 230 kV transmission lines, Sugar Pine Dam and community drinking water supply, Ralston hydroelectric powerhouse and cellular and microwave transmission towers.
Multiple reports and photos posted on social media Wednesday evening indicated that flames devoured some homes, structures and cars in Michigan Bluff, a historical Gold Rush town about 7 miles east of Foresthill overlooking the North and Middle forks of the American River.
Cal Fire spokesperson Chris Vestal said the agency has received reports of burned structures in Michigan Bluff, but he said he could not comment on the number of structures destroyed. Damage assessments are on the ground and will have more information as soon as possible, he said.
Vestal also said flames had not pushed into Foresthill proper and were still a few miles from downtown Foresthill.
Damage from the #MosquitoFire along Michigan Bluff Road near High Street pic.twitter.com/6wj9Uhdimj
The fire started in the Tahoe National Forest at 6:27 p.m. on Tuesday near Oxbow Reservoir 3 miles east of Foresthill amid a record-breaking heat wave in California that sent temperatures soaring above 100 degrees for several days straight. Hundreds of people were forced to flee their homes, and evacuations remain in place Thursday morning. (The live evacuation map is the best source for updated evacuation information.) The fire is burning through vegetation that was left parched and highly flammable after days of scorching weather. The acreage burned went from 5,705 acres on Wednesday night to 6,870 acres on Thursday morning.
Brent Wachter, a fire meteorologist at the U.S. Forest Service’s Geographic Coordination Center in Redding, said the extreme dryness of the landscape was evident in the overnight hours after the fire first broke out. Fires often calm down after sunset when winds subside and temperatures drop, but the Mosquito Fire continued to burn — and the same thing happened Wednesday night.
A flag flies behind a scorched outbuilding as the Mosquito Fire burns along Michigan Bluff Road in unincorporated Placer County, Calif., on Wednesday.
“That’s how flammable the fuels are. Fires are even growing actively overnight,” Wachter told SFGATE on Wednesday.
Smoke from the fire spread across the Sierra foothills and flooded the Lake Tahoe basin. Placer County’s health department issued an air quality advisory warning of unhealthy air through Friday.
Vestal said conditions similar to Wednesday were expected Thursday with critical fire behavior and growth.
“Because of the terrain and the conditions, it’s really hard to put in containment lines,” he said.
Amy Graff is the news editor for SFGATE. She was born and raised in the Bay Area and got her start in news at the Daily Californian newspaper at UC Berkeley where she majored in English literature. She has been with SFGATE for more than 10 years. You can email her at agraff@sfgate.com.
Katie Dowd is the SFGATE managing editor.