At this point, we’re all victims of the poor air quality in Northern California because of the wildfires burning in the coastal range and the Sierra Nevada.
But while Sacramento, and other parts of the state, are getting a moment away from the dark skies and thick air, experts say don’t get too comfortable.
“We have had a little bit of a reprieve because we had some unforeseen heavier winds, but we do expect a build up again,” said Jamie Arno, spokesperson for the Sacramento Metropolitan Air Quality Management District.
Arno says the coming days should be clear in valley areas, but the air in much of the state’s mountains will likely still be smoke-laden. From Saturday to Tuesday Sacramento is expected to have temperatures in the triple-digits and mountain areas are supposed to be in the 90s.
Making plans for the holiday weekend?🗓️ Be sure to take into account the forecast. Heat risk will range from high to very high with the hottest day on Sunday.— NWS Sacramento (@NWSSacramento) September 3, 2020
Daily records and even September monthly records will be jeopardized. 🌡️
Be safe and beat the heat! #CAwx #CAheat pic.twitter.com/InIvilXpLF
“We're at the mercy of the winds,” she said. “We're going to have good days and we're going to have bad days for the foreseeable future.”
The smoke and haze are the result of multiple fires, but the air quality still isn’t as bad as when the 2018 Camp Fire dropped ash on cars and streets in places like Sacramento.
“It seems really bad because we've been living with it for about two weeks,” she said. “But when you look at it in comparison, historically, to the Camp Fire … that was actually probably 50% worse smoke impact wise and pollution wise than this episode.”
The conditions that led to the most recent fires in the heat of summer — multiple days over 100 degrees — are expected to return this weekend. And Arno expects the air quality will worsen again.
That’s because of an inversion layer acting like a cap over the region not allowing smoke and particles to escape, according to Michelle Mead, a warning coordination meteorologist with the National Weather Service in Sacramento. She says to think of an inversion layer like a pool where there’s a layer of warm water at the top and the bottom is cold.
“The cold air sinks to the bottom because it's heavier,” she said. “And then as it's rising, it kind of stops — it can't escape.”
She says usually the sun will eventually help warm all the layers of air, breaking up that inversion layer. But the smoke acted as a barrier to that process, she explained.
“When we have that smoke that's trapped at and below the inversion, it reflects the sun off so it won't allow it to equalize and mix the smoke away,” she said.
Because of the looming inversion layer, Mead says people need to plan for hotter days with bad air quality, which likely means staying indoors.
“I don't want folks to let their guard down because it has been beautiful this week,” she said of temperatures just below normal highs in the valley. “People are getting ready to do their Labor Day plans and probably noticed the forecast and the heat this weekend. The reason that is happening is we have a really large dome of hot air that's currently over the desert southwest that's going to build north.”
That means a greater chance that skies may darken again, because wildfire smoke won’t be able to escape. She also notes climate change is creating more hot days and says though meteorological fall began Sept. 1 we can expect a hot, dry autumn because there’s no substantial precipitation in the forecast.
“Mother Nature didn't get the memo,” Mead said. “She's making sure we have one last hurrah of summer for the Labor Day weekend, and she's definitely going to make her mark because we're looking at record breaking heat with the big determining factor of how much smoke fills the valley.”
She says a saving factor could be wind, like we saw this week move particulates out of the area. But so far next week’s forecast doesn’t look promising. Although, wind at the wrong time is also dangerous because it can help wildfires grow substantially.
“A heat event like this can cause any fire to pick up quickly and take off,” she said. “So we are reminding folks to be fire wise. Don't drag chains. Don't be weed eating in a dry field with lots of rocks or anything like that. Just be safe.”
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