(FOX40.COM) — Thunderstorms are not a common occurrence in California compared to other regions of the country, but these storms bring one of the greatest natural threats to California: lightning-caused fires.
Each year thousands of lightning strikes across the state ignite devastating wildfires that create a series of challenges and dangers for both fire crews and the public.
In recent weeks, Northern California has seen nearly countless lightning strikes that have sparked wildfires from the Lake Tahoe Basin to the California/Oregon border, torching several thousands of acres of forestland.
On Friday, FOX40.com spoke with United States Forest Service spokesperson Adrienne Freeman to get a better understanding of the nature of these lightning-caused fires.
From the Weaverville Ranger Station, about 20 miles from the lightning-caused Deep Fire, Freeman explained the extremely dynamic nature that a lightning-caused fire can bring.
Unpredictable Winds Sporadically Spread Lighting Caused Fires
“Lightning is accompanied by convective activity that has abundant activity,” Freeman said. “It takes out normal wind patterns and makes them random.”
A normal wind pattern would have daytime activity of winds moving up a canyon and at night doing the opposite and working down the canyon.
These predictable wind patterns make it easier for fire crews to make containment lines around the fire and for incident commanders to map the potential spread direction of the fire.
“When you add the convective activity to that model you can get wind that can go in any direction sporadically and very strong,” Freeman said.
Freeman said these winds can range in speeds from 20 to 70 miles per hour.
These unknown and hard-to-predict wind patterns make it nearly impossible for fire crews to establish successful fire lines as the fire is able to move in any and all directions.
This convective activity also poses a threat to the public as fire behavior can change significantly in a short amount of time.
So a community that hours earlier was not in major danger from a nearby fire could be placed under evacuation orders as the unpredictable winds shift and place them in the line of the fire.
Dry Lighting vs Lighting with Precipitation
In 2020, California was barraged with around 12,000 dry lightning strikes in August that sparked hundreds of fires across the state.
Dry lightning is cloud-to-ground lightning without accompanying any rainfall or rainfall less than .10 inches.
It takes at least a quarter-inch of rain in a single strike area to provide enough moisture to reduce the chance of a lightning-caused fire.
Rainfall can be a blessing and a curse for fire crews working on an active fire though as added moisture in a fire-damaged area can cause soil to become extremely unstable and may even cause dead standing trees to fall.
Freeman said the reason there were so many fewer lightning-caused fires in 2022 was that there was enough accompanying rainfall to maintain high moisture levels in any potential material that could fuel a fire.
One misconception for the 2023 fire season though, is that there is still a high moisture content in potential fuels, when really conditions are extremely dry for fuel beds across the state.
From Aug. 16 to Aug. 17, there have been at least 1,000 lightning strikes in Northern California that had the potential to start incredibly devastating fires, according to Freeman.
“That means that crews are divided up looking for new starts, assessing new starts, prioritizing new starts,” Freeman said. “We are not talking about one or two (fires) either, it’s more like 100, 200 and maybe even 400.”
Challenges of Detecting and Accessing Lightning-Caused Fires
Many of the thunderstorms that produce these intense lightning storms occur at high elevations, in dense forests and in extremely difficult terrain making immediate detection difficult.
These difficulties have forced innovations in detection methods beyond the tried and true fire watchtowers that dot the peaks of some of the most fire-prone areas of the state.
Freeman said that the newly created Alert California camera network system and the use of unmanned aerial surveillance by drone has increased fire agencies’ ability to spot remote lightning-caused fires in rugged areas.
“So you have the combination of really quickly advancing technology in artificial intelligence that can hone in on what they think is a fire with a camera that is remote, but we can’t forget the detection importance of our old school lookouts,” Freeman said.
However, even the most advanced detection system in use right now can not overcome lightning-caused fires’ greatest danger, “sleepers.”
As Freeman explains, when lighting strikes occur in an area of heavy dead and down fuels like fallen trees, pilled undergrowth or piled leaves it allows embers to smolder undetected.
This dense organic coverage can allow fires to smolder in areas that did receive enough rainfall to snuff out most other lighting-caused fires.
These sleepers can continue to spread through the underbrush and dense groundcover before even spreading up and into the understory of a forest.
“It may be that there is no indication that a fire exists for three or four days after a lighting bust went through,” Freeman said.
These delayed starts mean that all detection methods must remain vigilant for several days following a lightning storm to ensure that there isn’t one hiding in the undergrowth.
The Effects of Climate Change and Future Storm Modeling
A 2014 study by UC Berkeley found that warming conditions may result in 50% more lightning strikes by the end of the century.
More specifically the study indicated that every 1 Celsius increase in the temperature causes a 12% increase in lightning strikes.
Freeman said that the challenge for fire agencies going forward is determining if these extremes in average weather conditions are going to become the new average.
“We are way outside of averages in a lot of different ways, setting heat records and setting moisture records for vegetation,” Freeman said, “Are they anomalies, or is it a new normal, and how do you deal with averages, and assessment, and modeling when things are happening so much in the extremes.”
As a hurricane is looking to make landfall on California’s coast for the first time in almost a century it seems like Freeman’s concerns have grounding.