Fire risk increases as McKinney fires spread in Northern California

“Any time lightning strikes, especially in the middle of summer in the western United States during a heat wave, there’s definitely concern,” said Nick Nausler, a fire meteorologist with the National Interagency Fire Center. “We think we’re going to see ignitions and a lot of significant fires.”

In an ominous sign of underground conditions, a new wildfire — the McKinney Fire — is spreading rapidly near the California-Oregon border after thunderstorms since Friday. It grew explosively Friday night and Saturday with intense fire behavior A towering pyrocumulonimbus cloud, or fire-generated thunderstorms. Radar Lightning detected Unleashed by a storm.

Incredibly, the fire had already grown 30,000 to 40,000 acres Saturday afternoon, according to the Klamath National Forest.

Mandatory evacuation orders have been issued for a wide area surrounding the fire, and two smaller fires are burning nearby.

There are concerns that fires could spread rapidly amid hot, dry conditions near a zone With no recent fire historyThis means that a large amount of fuel (dry and dead vegetation) can be ignited.

The National Weather Service in Medford, Ore., issued a red flag warning for high fire danger in the area Saturday and Saturday evening. The warning was extended until Sunday afternoon.

“Lightning and high fire risk can cause new fires. Thunderstorm winds will contribute to fire spread,” it wrote. “Despite rain, initial attack resources may be high and holdover fires are possible.”

The region has been roasting for the past week under a heat dome, a ridge of high pressure in the upper atmosphere. There is a dome Prediction will weaken and move eastward over the weekend allowing a small intrusion of moisture from the southwest monsoon into next week. Meanwhile, an approaching trough, or sink into the jet stream, will produce winds and lower temperatures, and act as a trigger for organized thunderstorms.

Under this system, storms can move very quickly, dropping very little rain in a given location, increasing the chances of lightning strikes over dry land.

“This is a classic 1-2 critical fire weather punch, following a previous extended and intense heat wave that broke the ridge,” said Brent Wachter, fire meteorologist at the Northern California Geological Coordinating Center in Redding, Calif. via email. Typically multiple lightning strikes lead to large fires … with strong storm surges and/or increases in linear winds.”

Although the California fire season so far has not been as intense as the previous two years, that could change quickly after the August 2020 lightning strike in Northern California. That year brought a modern record of 4.3 million acres burned in the state.

From long-term severe drought to severe drought, this week’s rising temperatures have burned a swath of the West, as shown in a map of the metric’s energy output component, a measure of vegetation flammability.

“Typically, locations experiencing local ERC values ​​above the 95th percentile are more likely to survive initial fire suppression efforts and have an increased chance of ignition becoming a large fire,” said John Apatzoglou, a climatologist at the University of California, Merced. Email. “Notably, this becomes an even greater problem when a large geographic area simultaneously experiences high fire intensity and/or when numerous large fire events are active that exhaust existing fire suppression resources.”

According to Apatzoglou, heat waves can increase the fire season, especially long-lasting heat waves.

Heat has been rising across the interior of California in recent weeks, and may have had a hand in spreading the oak fire outside Yosemite National Park. The fire broke out without much wind among the thick, candied dry vegetation. The fire has destroyed 109 single-family structures and is 52 percent contained as of Saturday.

“Although June has been a relatively quiet month, we’ve consistently avoided the heat, and things have changed over the past 3 weeks,” Apatzoglou wrote, noting that Fresno, Calif., could experience its second-longest streak of days above 100 degrees Fahrenheit. By next week.

Record highs for July 29 were set for Friday with temperatures ranging from 100 to 115 degrees across Northern California and the interior of the Pacific Northwest. Some places are nearing all-time highs — or highest temperatures for any month. Mount Shasta, Calif., hit 106 degrees, one degree below its all-time low, and Medford reached 114, one degree below its all-time high.

A study Recently published in the Journal of Climate, of which Abatzoglou is a co-author, large fires in North America are seven times more likely to start during consecutive summer heat waves. Many studies have linked increasingly frequent and intense heat waves, as well as increases in wildfire activity and burned area, to human-caused climate change.

While a cooler weather is expected next week, fire danger is forecast to be high in August, and severe autumnal “coastal” winds could arrive in early September.

“This means that the door is open for ignitions to turn into complex fires,” Apatzoglou wrote. “Widespread dry lightning … as well as wind events are certainly worth watching as they have the potential to dramatically alter the course of the 2022 fire season.”

Jason Samenow contributed to this report.