California wildfires: State faces record-setting 121 degree heat as devastating blazes rage on

Firefighting operations continue to be extremely challenging because of triple-digit heat and extremely low humidity levels

Much of California endured one of its hottest days in memory on Sunday, the day after scorching temperatures set scores of records and intensified destructive wildfires erupting in the state.

Red-flag warnings for high fire danger covered the state while the heat fueled fires already burning as well as new blazes.

Numerous locations in California experienced their hottest September day on record on Sunday. A few spots saw their highest temperatures observed in any month.

Woodland Hills, 20 miles from downtown Los Angeles, soared to 121 degrees, the highest temperature ever observed in Los Angeles County. Chino, 32 miles east of Los Angeles, also hit 121 degrees. The Chino and Woodland Hills temperatures were the highest recorded west of the mountains in Southern California.

Farther north, the readings in San Luis Obispo, 10 miles from the Pacific Ocean, reached 120 degrees. This may be the highest temperature ever measured so close to the ocean in the Americas. Downtown San Francisco reached 100 degrees, a record for the date.

The heat helped fuel a wildfire that developed Saturday when the Creek Fire in the Sierra National Forest erupted, about 290 miles north of Los Angeles. The blaze was detected Friday night and rapidly grew to at least 45,500 acres by Sunday afternoon.

That fire trapped about 1,000 people near Mammoth Pool reservoir as flames crossed the San Joaquin River, including about 150 people who became stranded at a boat launch, The Associated Press reported.

According to the AP, 200 people were rescued from the Mammoth Pool Campground by military helicopters. Two people were severely injured, 10 had “moderate injuries” and others had minor or no injuries. According to the California Air National Guard, this was the largest wildfire-related air evacuation in recent memory.

The Fresno Bee reported that at one point, people trapped by the flames were told to jump into the water as a last resort if the fire got too close. However, Sierra National Forest officials said that the fire burned around the reservoir and that the air evacuations took place because the blaze blocked evacuation routes.

The Fresno sheriff ordered new evacuations on Sunday morning as the fire grew.

The Creek Fire sent smoke, embers and fine particles at least 45,000 feet in the air Saturday and Sunday, forming a pyrocumulonimbus cloud. Such clouds, which look like explosions from a distance, are fire-driven weather systems. The one seen on Saturday was causing lightning to strike areas downwind along with erratic and gusty surface winds. Ash fell more than 10 miles from the fire.

Fires this weekend are what are known as plume-dominated blazes, which occur when the environment is favorable for the upward billowing of smoke and vertical transfer of heat.

Plume-dominated fires can become firestorms, taking on the structure of a thunderstorm because of their vertical release of heat. Extreme fire behaviour, as has been seen with the Creek Fire, is often a characteristic of plume-dominated fires.

The Creek Fire appeared to produce fire tornadoes based on Doppler radar data, which revealed vortices inside the fire and a smoke plume that matched the size and shape of tornadoes.

A change of wind speed and direction with height known as wind shear caused the smoke plume to rotate. In an unusual turn of events, the smoke plume's updraft also appeared to repeatedly split, with pairs of spinning rotations repeatedly forming and drifting away from one another.

The Loyalton Fire in Lassen County produced five or more fire tornadoes barely three weeks ago, prompting the National Weather Service to issue a first-of-its-kind fire tornado warning.

In addition to the Creek Fire, firefighters are still dealing with the second-, third- and fourth-largest fires in state history, which erupted during a mid-August heat wave and unusual thunderstorms north of San Francisco. Although those fires are better contained, the heat, dry weather and shifting, strong offshore winds are causing an uptick in their activity.

Since 15 August, the state has seen more than 1.6 million acres burned, 900 new fires started, eight deaths and nearly 3,300 destroyed structures. About 310,000 acres are burned in an average California fire season, according to Cal Fire, the state firefighting agency.

Daniel Swain, a climate researcher at UCLA, said the state may set a record for the “most acres burned in the modern era” as soon on Monday.

Firefighting operations will continue to be extremely challenging because of the triple-digit heat and extremely low humidity levels, according to the National Weather Service.

Forecasters are monitoring two periods for strong, desiccating offshore winds to pick up in strength early this week.

The first looked as though it would take place through Monday evening, with the next taking shape as a rare early season Santa Ana wind event in Southern California from Tuesday into Wednesday.

The National Weather Service's forecast office in Los Angeles is predicting “elevated to critical fire danger” through Wednesday.

Many temperatures across the state appeared to be headed toward record territory by late Sunday as a “dangerous to potentially deadly” extreme heat event continued, the Weather Service said. The Weather Service office in Los Angeles described Sunday's heat as “kiln-like”.

Some all-time high temperatures and numerous daily records are in jeopardy as a sprawling and unusually potent area of high pressure, also known as a heat dome, covers the West.

In a sign of the heat to come, temperatures in some locations, from the San Fernando Valley to parts of Los Angeles County, did not drop below the 90s on Saturday night into early Sunday morning. In fact, two temperature stations in the LA area were still hovering above the century mark at 3.02am local time, the National Weather Service stated.

High temperatures in Southern California on Sunday ranged from 105 to 115 degrees near the coast to up to 120 degrees in inland areas, which would edge past all-time high-temperature records in some locations.

Some noteworthy temperature records that have already occurred include:

- The 121-degree temperature recorded in Woodland Hills was not only the highest temperature on record there but also the highest seen anywhere in Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties, the National Weather Service said.

- Burbank tied its all-time high temperature record of 114 degrees Saturday.

- Palm Springs hit 122 degrees, breaking its previous September record from 1950.

- Death Valley set a September record with a high of 125, overtook the record of 123, set in 1996. This comes just weeks after hitting 130 degrees, an August record, and the highest temperature observed globally since at least 1931.

- Woodland Hills in Los Angeles tied its all-time high temperature record of 119 degrees, set in July 2016.

The massive heat dome sprawled over western North America established September records from Mexico to the Colorado Rockies. Mexicali, Mexico, soared to 121.1 degrees, the country's highest temperature ever observed during the month. Denver hit 101 degrees, its highest September temperature and the latest on record it has crossed the century mark. Nearby Boulder reached 99 degrees, its highest temperature so late in the year. On Tuesday, Denver and Boulder are expecting snow.

La Junta, in Colorado, about 60 miles southeast of Pueblo, registered a high of 108 degrees, a state record for the month of September.

Temperatures are forecast to cool some by Tuesday but remain above normal in most of California for much of the week.

Human-caused climate change is tilting the odds in favor of more frequent, severe and longer-lasting heat waves, as well as larger wildfires throughout large parts of the West. Research published last month shows that climate change is tied to more frequent occurrences of extreme-fire-risk days in parts of California during the fall. (Meteorologists define the fall as beginning on 1 September.)

Michael Wehner, who researches extreme weather at Lawrence Berkeley National Laboratory, estimates that “climate change has caused extreme heat waves to be 3 to 4 degrees Fahrenheit warmer in California”. These trends “will continue as the planet continues to warm,” Mr Wehner said in an email, noting that the amount of warming will depend on future greenhouse gas emissions.

The heat wave has prompted warnings from the operator of California's electricity grid that rolling blackouts may need to be instituted during times of peak power use, and it has asked residents to take steps to reduce electricity use during times of peak demand. A “Stage 2 warning” was issued on Saturday, indicating that all efforts to prevent power failure had been taken, but it was not followed by outages.

The California ISO declared a “Flex Alert” on Sunday, calling for reduced electricity use between 3pm and 9pm local time.

The state utility PG&E has also warned that it may institute rolling outages if winds get too strong early this week because its power infrastructure has been blamed for sparking some of the state's largest and deadliest blazes in recent years.

Extreme heat has been the top weather-related killer in the United States during the past 30 years, and combined with poor air quality from nearby fires and the coronavirus pandemic, the health threat is particularly acute. Air conditioning provides the best protection from excessive heat, but rather than risking exposure to the virus at cooling shelters, the pandemic may keep people who lack air conditioning at home.

The Washington Post