Yes, We Got A Lot Of Rain This Year, But The Fire Danger Is Still Very Real
But good news: so far, things don't appear as ready to burn as in previous years. But don't stop prepping, because that danger is still very real.
LOOKING AT MOISTURE TO ASSESS FIRE DANGER
One of the key factors when assessing fire danger is the moistness of the vegetation. When it was raining all the time, plants were soaking up a lot of that water, which helped them produce new growth and keep their limbs well hydrated.
Usually by August, they've dried out to dangerously low levels, but this year they're holding on a bit longer, in part due to cooler summer temperatures.
"Because of the winter that we had and the amount of rain, we still have fuel moisture at a pretty good level," said Alberto Ortega, patrol prevention captain for the U.S. Forest Service.
Look at this fuel moisture chart and you'll see what he means (click for larger version).
Samples taken from Trippet Ranch in Topanga show that moisture levels peaked at 158 percent back in March, which is pretty high. Since then, they've been steadily falling, though not as quickly, or as much as last year.
As of last week, chamise at Trippet Ranch recorded moisture levels at 77 percent. That's still better than the 60 percent by this same time last year.
Though, Dave Gomberg, fire weather program manager at the National Weather Service in Oxnard, said that any moisture levels below 80 percent is worrisome.
"The main difference is that it's just taking a lot longer to get to this point [in moisture levels]," Gomberg said. "Fuels always gives you the potential of what's going to happen, but the weather is the driving force of what's going to kick it into gear."
Ortega said officials watch for the 60 percent threshold.
"At 60 and below, you're going into critical conditions," he said. "That is basically, we need to start looking at how we're staffing, precautions that we might have to take."
They'll consider additional fire restrictions as well, he said. Right now, you can have an open fire at a developed campsite. However, drier, windier and hotter conditions can mean no fire at all.
Interestingly, all that late-summer California heat long-prognosticated by seasonal forecast models seems to be coming to fruition. And despite fire season's slow start, it may ramp up very fast now that vegetation is reaching/exceeding typical peak summer dryness. #CAwx #CAfire https://t.co/kficTT7i22— Daniel Swain (@Weather_West) August 19, 2019
HISTORY REPEATS ITSELF
You don't have to go back far to find similar conditions that had catastrophic results.
The 2016-2017 rainy season saw nearly as much precipitation across our region (22.48 inches) as this year (22.84 inches), though over a much shorter period of time.
That drought breaking rainy season was followed by high temperatures that saw fuel moisture fall to dangerously low levels by late August and early September. In December, we were ravaged by the Thomas Fire, California's largest wildfire in state history (a record that was short lived). Our rainy season didn't show up to give us a reprieve until January.
After years of vegetation killing drought and a boost of growth the year prior, California was even more primed to burn in 2018, which took the record for worst fire year for us, ever.
It's obviously not just fuel moisture that determines whether fires spread. Wind, ignition source, location, density of vegetation and availability of firefighting resources, all play roles as well. However, fuel moisture and how it changes over time is something to watch for.
"The potential is still there, because Southern California can have those hot and dry temperatures that persist into the fall and winter months," said Jessica Gardetto, spokesperson at the National Interagency Fire Center especially in Southern California.