Forecasters predicted earlier this year that, due to an extended period of very dry conditions, parts of the United States are under extreme forest fire danger this season. That warning seemed to be playing out this week when wildfires erupted in California.
A thousand-acre wildfire in the foothills east of Los Angeles, CA, didn’t grow overnight Wednesday and was 10 per cent contained, authorities said Thursday. The blaze erupted in the foothills of the San Bernardino National Forest. However, hot Santa Ana winds—which can fan and spread the blaze—were forecast to return. Officials hoped calmer winds would allow firefighting helicopters to take to the air.
There was also a heightened risk of wildfire for most of Riverside County, CA, Wednesday as a surge of strong Santa Ana winds blowing amid dry and warm conditions bore down on the metropolitan areas and mountains for the second consecutive day, meteorologists said.
It was the hot early-season wind, particularly the Santa Anas, which — if coming after repeated dry spells — were cited as a main reason for California’s rising fire danger.
The Santa Ana winds, which blow hot air from California’s desert through passes and canyons, were gusting at up to 80 miles per hour at times Wednesday, pushing the flames across scrub and forest land left bone-dry by the state’s severe, multi-year drought.
The National Weather Service (NWS) issued both a red flag warning and a high wind warning Wednesday for the mountains and valleys of Riverside County, CA, but not the Coachella Valley. The red flag warning, which is the agency’s most serious fire-related warning, was scheduled to expire at 8 pm Thursday, while the high wind warning — signalling winds strong enough to cause damage — was scheduled to expire at 5 pm Thursday.
“Sustained winds during this time will range from 20 to 40 miles per hour with gusts of 40 to 60 mph over the foothills and valleys,” the NWS said, adding that peak winds of 60 to 90 mph are likely in a few of the wind prone mountain and foothill areas.
US Forest Service officials added that fire crews were continuing to build containment lines around the blaze. Mandatory evacuation orders for 1,650 homes were cancelled, though residents were urged to prepare to leave at a moment’s notice. Nine schools near the fire remained closed as temperatures in the area were expected to top 100 degrees Fahrenheit.
At one point, utilities reported about 8,000 people had lost power Wednesday due to downed power lines and other wind-related problems.
The fire erupted in the midst of a heat wave that has sent Southern California temperatures into the 90s in some areas.
High temperatures were expected to continue through Saturday, with humidity in the single digits.
The fast-moving blaze, which sent smoke drifting across much of Southern California all the way to the Pacific Ocean, came amid a dangerous combination of unseasonably hot weather and fierce Santa Ana winds that put much of Southern California’s brushy hillsides at risk.
“The bad news is, we’re going to have some tough, hot, dry, windy conditions to fight that fire, and in case any other fire gets started, it’s going to spread quickly,” said Miguel Miller, a forecaster with the NWS Thursday. “The good news is, conditions will improve this afternoon.”
Meanwhile, sustained winds blowing southwest continued to push plumes of smoke and ash into Rancho Cucamonga and beyond Thursday.
The winds, however, should begin to subside after noon, and drop to a “light breeze” by the evening, Miller said.
Beachwood, in New Jersey’s Ocean County, became engulfed by a brush fire April 24. At the time of the blaze the National Weather Service had already issued a red flag warning, the day prior. Between 150 and 200 acres were burning east of the Garden State Parkway near exit 77, and the fire covered about 300 acres, according to fire officials at the scene.
That morning a 1,500-acre forest fire was burning in Cumberland County, near the Delaware Bay – and forecasters said even a stray cigarette butt could cause problems anywhere in New Jersey.
“The next three to five weeks is actually our worst period unless we have a drought in the summer,” said Stephen Maurer, assistant state fire warden, to the Sand Paper Thursday. “It has a lot to do with the angle of the sun. We have a lot of sun coming down right now. And there’s the fact we don’t have leaves on the trees yet, so all that sunlight is down on the forest floor.”
Jim Bunker, National Weather Service observing program leader, said the weather service uses computer models to predict when conditions are likely to pose a potential for forest fires. He added that there are also people who go out to test the “fuels” that can ignite a forest fire. These “fuels” include grass, brush, timber and slash. Once these fuels are recorded, a fire’s rate of spread and intensity can be measured.
Elsewhere, a new study examining tree rings has determined that current, or even recent, drought conditions in the US are nothing compared to history. The study of climate data taken from trees in the Western US reveals levels of drought that were significantly worse than anything experienced in the past century.
Brigham Young University professor Matthew Bekker analyzed rings from drought-sensitive tree species going back to the early 1400s. He found several types of scenarios that could make life uncomfortable in the western US:
Long droughts: The year 1703 kicked off 16 years in a row with below average stream flow.
Intense droughts: Utah’s Weber River flowed at just 13 per cent of normal in 1580 and dropped below 20 per cent in three other periods.
Consecutive worst-case scenarios: The most severe drought in the record began in 1492, and four of the five worst droughts all happened during Christopher Columbus’ lifetime.
For this study, Bekker took sample cores from Douglas fir and pinyon pine trees. The thickness of annual growth rings for these species is especially sensitive to water supply.
Using samples from both living and dead trees in the Weber River basin, the researchers built a tree-ring chronology that extends back 585 years into natural history. Modern stream flow measurements helped them calibrate the correlation between ring thickness and drought severity.
According to the authors, the west’s climate usually fluctuates far more than it did in the 1900s. The five previous centuries each saw more years of extremely dry and extremely wet climate conditions.
“We’re trying to work with water managers to show the different flavors of droughts this region has had,” said Bekker in the Journal of the American Water Resources Association Thursday. “These are scenarios you need to build into your models to know how to plan for the future.”