Fires in the Los Angeles area have made headlines this week, for being the most destructive in the history of the city, for afflicting so many familiar faces, and for sweeping through the area in January, when we should just be reaching the height of the wet season in California.
I don’t discuss climate change much here, because I like to distinctly separate climate from meteorology. To that end, it is important to distinguish that climate change did not cause this tragedy, but rather created an environment in which such a tragedy might occur. The long term effects of climate change are best left to discussion by climatologists, and those knowledgeable of the systems climate change will impact. While climate change did not necessarily cause the fires, as I said, the weather of the last year set the stage for the disaster, and the weather of the last couple of days may have caused the fires, and certainly made them exponentially worse. Don’t take my lack of discussion on the climate as any sort of commentary on anything other than – I am a meteorologist, and I am not an authoritative source on climatology. I can tell you all about the local, short term weather that made these fires what they are.
The first thing that you need to make a fire is the fuel for the fire. After years of drought, last winter was a wet one in California. A thirsty terrain was given a healthy drink of water at the beginning of 2024, and plant life that had been scoured through years of fire and drought came back and was replenished. And then, after the wet winter and early spring, it stopped raining, and it got dry again in southern California.
More recently, high pressure has settled into the southern Rockies behind a strong trough bringing the cold air and snow in the southeastern US. The flow around high pressure is clockwise, and positioned where it is, it will be off shore in southern California, meaning that it is dry. Additionally, because he high pressure was strong, and gravity and temperature changes between the sea and land played a bit of a role, the winds this session were absolutely howling over the Santa Ana Mountains. The wind was strong enough to cause damage on it’s own, including to power lines.
Most wildfires, especially in southern California, are of human origin, either because of the intentional setting of them, or more likely in this case, because of downed power lines, which is why power companies out west are sued so regularly. The downing of these power lines is also a problem, because power lines are near people. With a swelling population, there are more power lines and a greater exposure to a fire. Additionally, fires are now more likely to start near inhabited areas, simply because of the infrastructure covering more territory.
There isn’t any rain in the near future for southern California, however there is some hope in the form of reduced winds. High pressure does look like it will be tapering off early next week. As the fires are currently uncontrolled they will likely get worse before they get better first.