It’s a volatile combination in California; the wind, the fire season, and the historic drought. In the San Francisco Bay Area, for the past six weeks or so, the wind picks up every afternoon; there have already been two red flag alerts months before the fire season officially begins and brush fires along the 101 corridor are happening with more frequency.
Matt Mehle, a meteorologist with the Bay Area National Weather Service, must still be sheltering in place if he isn’t aware of the fact that the Bay Area has been windier this year earlier than usual. Mehle claims it just feels windier because both land and water temperatures are unusually lower than in previous years.
The magazine Nature recently published a study Climate Change which determined that since around 2010, winds “across much of North America, Europe and Asia have been growing faster . In less than a decade, the global average wind speed has increased from about 7 mph to about 7.4 mph”
And in a study in Will Global Warming Bring a Change in the Winds? Dust from the Deep Sea Provides a Clue, researchers report:
By using dust in ancient, deep sea sediments as an indirect tracer of wind, the researchers were able to reconstruct wind patterns that occurred three to five million years ago. Knowing that winds—in this case the westerlies—transport dust from desert regions to faraway locations, the authors examined cores from the North Pacific Ocean. This area is downwind from Eastern Asia, one of the largest dust sources today and a known dust-generating region for the past several million years. By measuring the dust in cores from two different sites thousands of kilometers apart, the researchers were able to map changes in dust, and in turn the westerly winds.
“We could immediately see the patterns. The data are so clear. Our work is consistent with modern observations, and suggests that wind patterns will change with climate warming,” said Abell.
Here in Northern California, the Diablo winds are the equivalent of Southern California’s Santa Ana’s during fire seasons. The Diablo winds, which begin in Contra Costa County, swell to gale-force during fire season; they were the main drivers behind the 2019 Kincade Fire in Sonoma County, the 2018 Camp Fire in Butte County, and the Wine Country fires in 2017 and 2018. This year, they are expected to supply the juice which could set off the worst fire season in Northern California history.
Diablo winds can happen at any time in the year, but they typically peak in October and November.
It’s the change from summer to fall that triggers the potential for such strong winds. During summer, winds come into California off the ocean, bringing cool, moist air. These are called onshore winds.
But as the days shorten, the high pressure that pushes winds inland from the Pacific weakens, and instead, higher pressure cold air moves into the Great Basin. This pushes winds that travel west over land, traveling up and across the Sierra Nevada, and down the other side, right at the time when California is at its driest. These are the dangerous offshore Diablo winds. KQED
Some stats on this year’s extreme drought:
Thanks in part to rising temperatures due to climate change, “extreme” or “exceptional” drought conditions are now occurring in 74 percent of the state of California, while 72 percent of the Western U.S. is classified as experiencing “severe” drought, according to data from the U.S. Drought Monitor.
With the risk of wildfires growing with every passing day in states like California, which receives only minimal precipitation during the summer months, temperatures last week continued to trend 3 to 6 degrees above normal, the Drought Monitor said on its website.
In May, California Gov. Gavin Newsom declared a drought emergency in 41 of the state’s 58 counties, putting in place water conservation restrictions Yahoo News
In a CBS News report “Mega-drought” in West means threat of extreme fire season ahead, Jeff Berardelli writes that after last year’s record setting fire season, extreme drought conditions indicate California is a “tinderbox” on the verge of a “catastrophic fire season.”
“That’s why it’s startling to see the comparison between last year’s relatively modest drought and this year’s record-setting drought. Drought conditions this time last year are a blip on the radar compared to where we are right now. ”
Moisture in the California’s plants is significantly lower than average for the month of April, when it is usually at its highest, according to San José State University’s Fire Weather Research Laboratory .
“Fire season 2021 is looking grim,” the state’s only wildfire research center said on Twitter.
In a May Ecowatch report, Olivia Rosane’s story California’s Wildfire Season Is Off to an Early Start reports on red flag warnings in mid-spring, despite fire season typically beginning in summer. “California is experiencing its driest wet season in more than 40 years; Sacramento experienced its driest on record in April, NWS said.”
The dry conditions exacerbate fires for two reasons, according to The Mercury News. There is no water to put out early flames, and dry weather speeds up the process of curing. Curing occurs when vegetation dries out to the point where its moisture content is impacted by the dryness of the atmosphere, not the soil.
“In a better scenario, we wouldn’t be dealing with this until the traditional fire season in the fall,” NWS Meteorologist Gerry Diaz told The Mercury News.
All of this follows 2020’s devastating fire season, when a record 4.1 million acres burned in California alone. It is too soon to speculate whether 2021’s season will be as bad or worse, even though it’s off to an earlier start, according to SFGate. State fire-fighting agency Cal Fire has so far responded to more than 1,354 wildfires since Jan. 1, 2021, with 2,219 total acres burned. By this time last year, Cal Fire had responded to 814 blazes burning 1,056 acres.